CN211046765U

CN211046765U - Switch control device and switch power supply thereof

Info

Publication number: CN211046765U
Application number: CN201921628556.XU
Authority: CN
Inventors: 宗强; 刘准; 吴寿化; 方芳
Original assignee: Shenzhen Chip Hope Micro-Electronics Ltd
Current assignee: Shenzhen Chip Hope Micro-Electronics Ltd
Priority date: 2019-09-27
Filing date: 2019-09-27
Publication date: 2020-07-17
Anticipated expiration: 2029-09-27

Abstract

The application provides a switch control device and switching power supply thereof, wherein, switch control device is used for controlling a switch unit break-make, and it includes: the sampling unit samples an inductive circuit in the switching power supply and respectively outputs a feedback signal for reflecting the output power supply of the inductive circuit and a sampling signal for reflecting the current peak value in the inductive circuit; the conduction detection unit is used for respectively detecting the feedback signals in different time periods and outputting a first conduction detection signal and a second conduction detection signal based on each detection result; the disconnection detection unit is used for detecting a sampling signal based on the feedback signal and outputting a disconnection detection signal based on a detection result; the logic control unit is used for controlling the switch unit to be switched on/off in a DCM mode or a QR mode based on the control logics of the switch-off detection signal, the first conduction detection signal and the second conduction detection signal. The application solves the problem that the switching power supply can not be well self-adaptive and stably supply power to different loads.

Description

Switch control device and switch power supply thereof

Technical Field

The present disclosure relates to a driving circuit, and more particularly, to a switching control device and a switching power supply thereof.

Background

The switching power supply is a device for converting electric energy, converts alternating current provided by a power grid into direct current for output, and is widely used for providing a driving power supply for electronic equipment requiring direct current power supply due to the advantages of high integration level, low cost, strong product adaptability, low standby power consumption and the like. Taking a mobile phone charger as an example, the switching power supply converts alternating current into direct current for charging the mobile phone, and the direct current is transmitted to the mobile phone through the data line, so that the mobile phone is charged.

However, for example, in a terminal electronic product, a user may use a universal data line on a charger to charge different types of mobile phones, which makes the switching power supply in the charger unable to provide constant voltage power supply due to the access of different loads.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present application aims to provide a switching control device and a switching power supply thereof, which are used for solving the problem that the switching power supply in the prior art cannot adapt to light loads and maintain constant voltage power supply for different loads.

In order to achieve the above and other related objects, a first aspect of the present application provides a switching control device for controlling on/off of a switching unit, wherein the switching unit is electrically connected between a power supply bus and a power conversion unit, the power conversion unit is configured to provide stable power supply to a load by an intermittent electrical signal generated by the switching unit, wherein the power conversion unit includes an inductance circuit configured to convert the intermittent electrical signal into both power supply to the load and energy storage of an energy storage circuit, and the switching control device includes: the sampling unit is coupled with the power conversion unit and is used for sampling the inductive circuit and respectively outputting a feedback signal for reflecting the output power supply of the inductive circuit to a load side and a sampling signal for reflecting the current peak value in the inductive circuit; the conduction detection unit is coupled with the sampling unit and used for respectively detecting the feedback signals in different time periods and outputting a first conduction detection signal and a second conduction detection signal based on each detection result; a disconnection detection unit coupled to the sampling unit, for detecting the sampling signal based on the feedback signal and outputting a disconnection detection signal based on a detection result; and the logic control unit is connected with the conduction detection unit and the disconnection detection unit and is used for controlling the switch unit to be switched on/off in a DCM (discontinuous conduction mode) or a QR (quick response) mode based on the control logics of the disconnection detection signal, the first conduction detection signal and the second conduction detection signal.

In certain embodiments of the first aspect of the present application, the sampling unit comprises: the first sampling module is coupled to the inductive circuit and used for obtaining a feedback signal reflecting load power supply based on a power supply signal output to a load side by the inductive circuit; and the second sampling module is electrically connected with one output end of the inductance circuit and is used for sampling the current peak value flowing through the inductance circuit so as to obtain the sampling signal.

In certain embodiments of the first aspect of the present application, the first sampling module comprises: the inductive sensor is coupled to an inductor which is used for generating a current peak value of power supply output to a load side in the inductive circuit so as to output an electric signal for reflecting the power supply of the load side; and the voltage division circuit is arranged on a line between the inductance sensor and the reference voltage terminal and used for outputting the feedback signal based on the electric signal output by the inductance sensor.

In certain embodiments of the first aspect of the present application, the inductive sensor further comprises a power supply unit for providing an internal power supply based on the electrical signal output by the inductive sensor.

In certain embodiments of the first aspect of the present application, the power supply unit comprises: the energy storage module is connected with the output end of the inductive sensor and used for providing power supply for the interior of the switch control device by virtue of the electric signal output by the inductive sensor; and the unidirectional conduction module is arranged on a circuit between the output end of the inductive sensor and the energy storage module.

In certain embodiments of the first aspect of the present application, the second sampling module comprises: and the sampling circuit is connected between the output end of the inductor which generates the current peak value based on the discontinuous electric signal in the inductance circuit and the reference voltage terminal and outputs the sampling signal.

In certain embodiments of the first aspect of the present application, the conduction detection unit comprises: the switch on-off period detection module is connected with the sampling unit and acquires a reference signal, and is used for detecting a signal in a first time period in the feedback signal based on the reference signal and outputting a first conduction detection signal based on a detection result; the first conduction detection signal is used for adjusting the on-off period of the switch unit; the demagnetization detection module is connected with the sampling unit, acquires a zero-crossing reference signal, is used for detecting a signal of a second time interval in the feedback signal based on the zero-crossing reference signal, and outputs a second conduction detection signal based on a detection result; the second conduction detection signal is used for indicating that the demagnetization of the inductor in the power conversion unit is finished.

In certain embodiments of the first aspect of the present application, the switch on-off period detection module comprises: the first input end of the error amplification circuit is connected with the sampling unit to obtain a feedback signal, and the second input end of the error amplification circuit receives the reference signal and outputs an error amplification signal obtained based on the feedback signal and the reference signal; the switch on-off period timing circuit is connected with the output end of the error amplification circuit and is used for carrying out switch on-off period timing based on the error amplification signal and outputting a first conduction detection signal when the timing is overtime; the time limiting circuit is connected with the error amplifying circuit and used for timing a first period of time based on the disconnection operation of the switch unit and outputting an overtime signal when the timing is overtime; wherein the time-out signal is used for limiting the error amplification circuit to receive the feedback signal.

In certain embodiments of the first aspect of the present application, the error amplification circuit comprises: an error amplification sub-circuit having a positive input terminal, a negative input terminal, and an output terminal; wherein the negative input terminal obtains one of the reference signal and the feedback signal from a first input terminal of the error amplifying circuit; and the compensation sub-circuit is connected with the positive input end and the output end of the error amplification sub-circuit, and is used for performing feedback compensation processing on the error amplification signal output by the error amplification circuit based on the gain of the error amplification circuit to obtain a compensation signal, and integrating the compensation signal with the other signal of the reference signal and the feedback signal and transmitting the compensation signal to the input end of the error amplification unit.

In certain embodiments of the first aspect of the present application, the switch on-off period timing circuit comprises: the timing capacitor and a charge-discharge circuit are connected with the timing capacitor and receive the error amplification signal; and/or, a timing counter and a counter control circuit connected with the timing counter and receiving the error amplification signal.

In certain embodiments of the first aspect of the present application, the disconnection detection unit comprises: and the first input end of the peak detection module is connected with the sampling unit to obtain a sampling signal, and the second input end of the peak detection module receives a peak reference signal generated based on the feedback signal, is used for detecting the sampling signal based on the peak reference signal and outputting a disconnection detection signal based on the detection result.

In certain embodiments of the first aspect of the present application, the second input terminal of the peak detection module is connected to the conduction detection unit to obtain a peak reference signal related to the feedback signal generated in the conduction detection unit.

In certain embodiments of the first aspect of the present application, the peak detection module comprises: and the comparison circuit is provided with a first input end for receiving the sampling signal, a second input end for receiving the peak value reference signal, and an output end for outputting a disconnection detection signal obtained by comparing the voltage of the sampling signal with the voltage of the peak value reference signal.

In certain embodiments of the first aspect of the present application, the conduction detection unit comprises: the CCM mode switch on-off period timing module is connected with the logic control unit and used for carrying out CCM mode switch on-off period timing when the switch unit is switched on and outputting a third switching-on detection signal when the timing is overtime; the logic control unit further receives the third conduction detection signal, and is configured to control the switch unit to be turned on/off in a DCM mode, a QR mode, or a CCM mode based on the control logic of the turn-off detection signal, the first conduction detection signal, the second conduction detection signal, and the third conduction detection signal.

In certain embodiments of the first aspect of the present application, the CCM mode switch on-off period timing module further performs a reset operation based on a later generated one of the second conduction detection signal and the first conduction detection signal during timing.

A second aspect of the present application provides a switching power supply, comprising: the rectifying unit is connected with an external alternating current power supply and is used for rectifying the connected alternating current and outputting the rectified alternating current to the power supply bus; the switch unit is connected to the power supply bus and controlled to be switched on/off; the power conversion unit is connected with the switch unit and used for providing stable power supply for a load by virtue of an intermittent electric signal generated by the switch unit, wherein the power conversion unit comprises an energy storage circuit and an inductance circuit which is used for converting the intermittent electric signal into consideration of power supply of the load and energy storage of the energy storage circuit; the switch control device according to any one of the first aspect.

As described above, the switching control device and the switching power supply thereof according to the present application have the following advantageous effects: the switch control device provided by the application adjusts the on-off time of the switch unit based on the feedback signal for reflecting the power supply of the load side, so that the switch power supply to which the switch control device belongs stably works in a plurality of modes, particularly in a plurality of modes including a QR mode, and therefore the adaptive stable power supply of the changed load is realized.

Drawings

Fig. 1 shows a circuit block diagram of a switching power supply.

Fig. 2 is a circuit structure block diagram of a switch control device in an embodiment.

Fig. 3 is a schematic circuit diagram of the switch control device.

Fig. 4 is a waveform diagram illustrating a feedback signal sampled by the first sampling module in the circuit configuration shown in fig. 3 during an on-off period of the switching unit.

Fig. 5 is a schematic circuit diagram of the switch on-off period detection module according to an embodiment.

Fig. 6 shows a further circuit schematic of the switch control device.

Fig. 7 is a schematic signal diagram of the switch control device and the switch unit in DCM mode.

Fig. 8 is a schematic diagram showing signals of the switch control device and the switch unit in the QR mode.

Fig. 9 is a circuit diagram of a conduction detection unit in a switch control device according to another embodiment.

Fig. 10 is a schematic signal diagram of the switch control device and the switch unit in CCM mode.

Fig. 11 is a schematic circuit diagram of an error amplifier circuit according to an embodiment.

Fig. 12 is a schematic circuit diagram of an error amplifying unit in the error amplifying circuit according to an embodiment.

Fig. 13 is a circuit configuration diagram of a compensation unit in the error amplification circuit according to an embodiment.

Fig. 14 is a circuit configuration diagram of an error amplifier circuit according to an embodiment.

Fig. 15 is a circuit configuration diagram of an error amplifier circuit according to still another embodiment.

Fig. 16 is a flowchart showing a method of generating an error amplified signal.

Fig. 17 is a flowchart showing a control method of the switch control device.

Detailed Description

The following description of the embodiments of the present application is provided for illustrative purposes, and other advantages and capabilities of the present application will become apparent to those skilled in the art from the present disclosure.

Although the terms first, second, etc. may be used herein to describe various elements in some instances, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, the first conduction detection signal may be referred to as the second conduction detection signal, and similarly, the second conduction detection signal may be referred to as the first conduction detection signal, without departing from the scope of the various described embodiments. But they are not the same preset threshold unless the context clearly dictates otherwise.

Also, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes" and/or "including," when used in this specification, specify the presence of stated features, steps, operations, elements, components, items, species, and/or groups, but do not preclude the presence, or addition of one or more other features, steps, operations, elements, components, species, and/or groups thereof. The terms "or" and/or "as used herein are to be construed as inclusive or meaning any one or any combination. Thus, "A, B or C" or "A, B and/or C" means "any of the following: a; b; c; a and B; a and C; b and C; A. b and C ". An exception to this definition will occur only when a combination of elements, functions, steps or operations are inherently mutually exclusive in some way.

The switch power supply is used as an energy conversion circuit, and provides an intermittent electric signal to a power conversion unit by the on-off of a switch unit, and the electric signal outputs stable direct current power supply to a load side through the energy conversion of the power conversion unit. In order to ensure stable power supply of the load side, a switch control device in the switch power supply acquires a feedback signal for reflecting the load power supply, and performs self-adaptive adjustment on the on-off of a switch unit according to the feedback signal. Wherein the self-adaptive adjustment comprises that the switching power supply provides stable power supply in a self-adaptive mode according to the acquired at least feedback signal. In order to solve the problem that the switching power supply is self-adaptive and the switching frequency, the peak current and the like are adjusted in different modes, the application provides the switching power supply and the switching control circuit therein.

Referring to fig. 1, a circuit block diagram of a switching power supply is shown. Wherein the switching power supply includes: a rectifying unit 11, a switching unit 13, a power converting unit 14, and a switching control device 12. Based on the power supply demand of the switching power supply adaptive load side, the switching control device 12 controls the on-off operation of the switching unit 13, so that the power conversion unit 14 can supply power to the load based on any appropriate one of the DCM Mode (discontinuous reduction Mode), the QR Mode (Quasi resource Mode), or the CCM Mode (continuous reduction Mode).

The rectifying unit 11 is connected to an external alternating current power supply, and is configured to rectify the connected alternating current and output the rectified alternating current to a power supply bus. The external ac power source is, for example, an adaptor, such as a socket, a terminal, etc., connected to the ac power grid. The rectifying unit 11 includes, but is not limited to, a full-wave rectifying circuit or a half-wave rectifying circuit. And the rectifying unit outputs the rectified electrical signal to a power supply bus. Here, the power bus 500 (also called VBUS) is a power line, which outputs the power signal rectified by the rectifying unit 11 to the load side for the load to access, so as to form a power supply loop.

The power supply bus 500 is connected with a switching unit 13 and a power conversion unit 14. The switch unit 13 has a control terminal (or referred to as a driving terminal), and includes a switch device that is turned on/off based on a voltage or a current of the control terminal. The switching device is exemplified by a BJT transistor, a Junction Field Effect Transistor (JFET), or a depletion MOS power transistor, etc.

The power conversion unit 14 is used for providing stable power supply to the load by the intermittent electrical signal generated by the switch unit. The power conversion unit 14 includes an inductance circuit for converting the intermittent electrical signal into a load power supply and a tank circuit for storing energy.

Here, the inductance circuit includes an inductor, and converts the discontinuous electrical signal transmitted by the power supply bus into a variable current by electromagnetic induction of the inductor on the variable electrical signal, so as to enable the energy storage circuit to perform energy storage operation. The inductance circuit includes a transformer provided based on a flyback switching power supply, an inductance provided based on a BUCK switching power supply, an inductance provided based on a Boost switching power supply, or the like. The energy storage circuit comprises a capacitor and is used for storing energy of the electric signal output by the inductance circuit after energy conversion and providing stable power supply for a load side by using the discharging operation of the stored electric energy.

The switching control device 12 controls the switching unit to be turned on or off by detecting a feedback signal reflecting the power supply on the load side, a feedback signal reflecting the demagnetization operation in the inductor circuit, and a sampling signal reflecting the current peak value in the inductor circuit, so that the power conversion unit is in at least the DCM mode or the QR mode.

Please refer to fig. 2, which is a block diagram of a circuit structure of a switch control device according to an embodiment. The switch control device 20 includes: a sampling unit 201, a conduction detection unit 202, a disconnection detection unit 203, and a logic control unit 204.

The sampling unit 201 is coupled to the power conversion unit 13, and is configured to sample the inductive circuit and output a feedback signal reflecting that the inductive circuit outputs power to the load side, and output a sampling signal reflecting a current peak in the inductive circuit, respectively.

The sampling unit is coupled to an inductive circuit in the power conversion unit by means of inductive coupling and/or an electrically connected inductor to obtain a feedback signal and/or a sampling signal.

The sampling unit samples the electric signal in the inductive circuit during the on period of the switch unit to output a sampling signal, and samples the electric signal in the inductive circuit during the off period of the switch unit to output a feedback signal. In some examples, the sampling unit may sample the input and the output of the power conversion unit, respectively, to obtain the feedback signal and the sampled signal, respectively. For example, the sampling unit samples the electrical signal flowing to the inductive circuit through the sampling switch unit to obtain a sampling signal; the sampling unit samples the electric signal output by the inductive circuit during the off period of the switch unit to obtain a feedback signal.

In still other examples, please refer to fig. 3, which is a schematic circuit diagram of a switch control apparatus, wherein the sampling unit includes a first sampling module 2011 and a second sampling module 2012.

The first sampling module 2011 is coupled to the inductive circuit 131, and is configured to obtain a feedback signal reflecting load power supply based on sensing a power supply signal output by the inductive circuit 131 to a load side. For example, as shown in fig. 3, in the flyback switching power supply, the inductance circuit 131 includes a transformer, and the first sampling module senses a primary winding of the transformer to obtain the feedback signal. For another example, not shown, in the flyback switching power supply, the first sampling module is connected to a secondary winding of a transformer, and the feedback signal is obtained by a secondary synchronous rectification circuit connected to the secondary winding. As another example, not shown, in the BUCK-type switching power supply, the inductor circuit includes an inductor, and the first sampling module is electrically connected to the inductor output terminal or senses an inductor electrical signal in the inductor. Herein, the first sampling module may also be referred to as a load feedback unit.

Some ways to obtain the feedback signal in the power conversion unit by using the peripheral circuit are that the first sampling module includes an inductance sensor and a voltage division circuit. Still taking the example that the inductance circuit in the power conversion unit includes a transformer, the inductance sensor (also called an auxiliary winding) is coupled to the primary winding of the transformer, and has a preset corresponding relationship with the number of inductance turns of the secondary winding, so that the induced electrical signal reflects the power supply of the load side and outputs a feedback signal. The inductive circuit may also be configured to be based on an inductive circuit in a BUCK-type switching power supply, or based on an inductive circuit in a BOOST-type switching power supply.

Wherein, the feedback signal obtained by the inductive coupling method is used for reflecting according to time sequence: the inductive circuit provides a power supply signal for supplying power to the load and a demagnetization signal of the inductive circuit during the turn-off period of the switching unit. Please refer to fig. 4, which is a schematic waveform diagram of the feedback signal sampled by the first sampling module in the circuit structure shown in fig. 3 during the on-off period of the switch unit. During the switching-off period of the switching unit based on the switching control signal Gate, the magnetic energy accumulated by the transformer and the auxiliary winding is converted into electric energy output by the secondary winding and the inductance sensor, that is, the secondary winding and the inductance sensor are both demagnetized, wherein the secondary winding and the inductance sensor are affected by the demagnetized process of the secondary winding, as shown in fig. 4, the feedback signal output by the inductance sensor is, for example, V_FBAs shown, the period t1 corresponds to a power supply signal during the supply of the secondary winding to the load, and the period t2 corresponds to a demagnetization signal during the demagnetization operation of the secondary winding. And the feedback signal output by the inductance sensor is divided by the voltage dividing circuit and then output to the conduction detection unit.

The second sampling module 2012 in the sampling unit is electrically connected to an output end of the inductor circuit, and is configured to sample a current peak flowing through the inductor circuit to obtain the sampling signal. The second sampling module samples an electric signal during the excitation of the inductive circuit.

Here, the second sampling module includes a sampling circuit sampling a voltage signal, which is connected between an output terminal of an inductor generating a current peak based on the discontinuous electric signal in the inductor circuit and a reference voltage terminal, and outputs the sampling signal. The discontinuous electric signal is a rectification signal output by the power supply bus during the conduction period of the switch unit. The second sampling module samples a rectification signal of the inductance circuit during the conduction period of the switch unit and outputs the rectification signal as a sampling signal to the disconnection detection unit. The reference voltage terminal is exemplified by a ground GND, and may be a circuit terminal for providing a constant voltage. Taking the example that the inductance circuit comprises a transformer, the second sampling module is connected between the output end of the primary winding of the transformer and the voltage ground, wherein one end connected with the primary winding outputs a sampling signal.

In the BUCK (or BOOST) switching power supply, the inductor circuit connected to the second sampling module corresponds to an inductor connected to the switching unit in the BUCK (or BOOST) switching power supply.

With the feedback signal and the sampling signal sampled as described above, the on detection unit in the switch control device is used to detect the on timing of the switch unit, and the off detection unit in the switch control device is used to detect the off timing of the switch unit.

The conduction detection unit is coupled with the sampling unit and used for respectively detecting the feedback signals in different time periods and outputting a first conduction detection signal and a second conduction detection signal based on each detection result.

Here, the conduction detection unit detects different types of signals represented by the feedback signal according to time sequences according to signals of different signal types that can be reflected by the feedback signal in different periods of the switching-off period of the switching unit, and outputs corresponding first conduction detection signals and second conduction detection signals. For example, the conduction detection unit detects power supply at the load side according to the feedback signal acquired at the first time period, and outputs a first conduction detection signal according to a detection result; and detecting the demagnetization finishing time of the inductance circuit according to the feedback signal acquired in the second time period, and outputting a second conduction detection signal according to the detection result. Taking the waveform diagram of the signal shown in fig. 4 as an example, the feedback signal reflects the load power supply in the time period t1 (i.e., the first time period), and reflects the secondary winding demagnetization operation until the demagnetization is finished in the time period t2 or (t1+ t2) (i.e., the second time period).

Based on the circuit framework shown in fig. 3, the conduction detection unit 202 includes a switch on-off period detection module and a demagnetization detection module (both not shown).

The switch on-off period detection module is connected with the sampling unit and acquires a reference signal V_{ref_FB}For a first period of time based on the reference signal V_{ref_FB}Detecting theFeeding back a signal and outputting the first conduction detection signal based on a detection result; the first conduction detection signal is used for adjusting the on-off period of the switch unit. For example, the first conduction detection signal is used for adjusting the conduction timing of the switch unit in at least one continuous on-off period.

Wherein the reference signal V_{ref_FB}May be provided based on the switching power supply supplying a constant voltage on the load side. The switch on-off period detection module detects the on-off period of the switch according to the reference signal V_{ref_FB}And detecting a partial signal used for reflecting the power supply of the load side in the feedback signal to determine the power supply deviation of the load side, and reducing the corresponding power supply deviation by adjusting the on-off period of the switch unit, thereby realizing the stable power supply of the load side.

Please refer to fig. 5, which is a schematic circuit diagram of the switch on/off period detection module according to an embodiment. The switch on-off period detection module comprises: an error amplifier circuit 311, a switch on/off period timer circuit 312, and a time limit circuit 313. The error amplifying circuit 311 is controlled by the time-limiting circuit 312, that is, the time-out signal output by the time-limiting circuit is used to control the error amplifying signal output by the error amplifying circuit not to be changed by the change of the feedback signal.

The time limiting circuit 313 is connected to the error amplifying circuit 311, and is configured to perform first time period timing based on the switching-off operation of the switch unit, and output an overtime signal when the timing is overtime; wherein the time-out signal is used for limiting the error amplification circuit to receive the feedback signal.

The time-limit circuit 313 may allow an input terminal of the error amplifier circuit to receive the feedback signal during the timing period, and prohibit the error amplifier circuit from receiving the feedback signal during the timing timeout, and the voltage of the feedback signal received before the timeout is maintained inside the error amplifier circuit 311. To this end, in some examples, the time-limiting circuit includes a capacitor for timing, and a first control circuit and a second control circuit of the capacitor, wherein the first control circuit and the second control circuit switch according to a switch control signal of the switch unit, and when the switch control signal indicates that the switch unit is disconnected, the first control circuit of the time-limiting circuit operates to start a timing operation until a voltage of one plate of the capacitor reaches a timing threshold voltage and the timing is timed out. And when the switch control signal indicates that the switch unit is conducted, a second control circuit of the time-limiting circuit works to start resetting the timing capacitor. The first control circuit and the second control circuit correspond to one of a charging circuit and a discharging circuit which comprise timing capacitors.

It should be noted that the circuit structure of the time-limiting circuit for performing the timing operation is not limited to the timing by using the charging circuit or the discharging circuit, and the timing operation may also be performed in combination with the circuit structure of which the charging capability and the discharging capability do not match, and therefore, detailed description is not given here.

In other examples, the time-limiting circuit includes a clock signal generator, a timing counter, a first control circuit and a second control circuit, wherein the first control circuit controls the timing counter to start counting the clock signal output by the clock signal generator based on a switch control signal for turning off the switch unit, and times out when a voltage corresponding to a count value reaches a timing threshold voltage; the second control circuit resets the timer counter based on a switch control signal of the time switch unit being turned on.

It should be noted that the circuit structure of the time-limited circuit for performing the timing operation is not limited to using the voltage corresponding to the count value to reach a timing threshold voltage as the timing timeout condition, and may also determine the timing timeout condition by detecting the overflow of the counter, and the details thereof are not described herein.

It should be noted that the timing circuit in each of the above examples may include a timing circuit structure having a timing counter and a timing capacitor, so as to respond to situations such as unstable timing threshold voltage, and use the timing logic represented by the digital circuit structure to output the first conduction detection signal based on the timing timeout signals of the two timing circuit structures. The digital circuit structure includes, for example, a circuit combination of one or more of the following: flip-flops, logic and gates, logic not gates, logic or gates, comparators, etc.

Under the control of the time-limiting circuit, the feedback signal V received by the error amplifying circuit 311_FBReflected load side power supply. A first input terminal of the error amplifying circuit 311 is connected to the sampling unit to obtain a feedback signal V_FBA second input terminal for receiving the reference signal V_REF1。

Here, the error amplifying circuit 311 at least includes an error amplifier and a buffer, wherein the buffer is connected to the time-limiting circuit, and is configured to maintain a voltage at an input terminal or an output terminal of the error amplifier before receiving the time-out signal based on the received time-out signal. To this end, the buffer may be located at the input or output of the error amplifier. The error amplifier is used for providing an error amplification signal between the feedback signal and the reference signal. In some examples, the reference signal V_REF1From the second input terminal to the positive input terminal of the error amplifier, and the feedback signal V_FBFrom the first input and through a buffer to the negative input of an error amplifier, the output of the error amplification circuit being amplified (V) based on the gain of the error amplifier_REF1-V_FB) The resulting error amplified signal V_COMP. In other examples, the error amplification circuit further includes an inverter, and the reference signal V is_REF1From the second input to the negative input of the error amplifier, and the feedback signal V_FBThe output end of the error amplifying circuit still outputs the amplified signal (V) based on the gain of the error amplifier after the inverting process of the inverter from the first input end and transmitted to the positive input end of the error amplifier through the buffer_REF1-V_FB) The resulting error amplified signal V_COMP. Error amplified signal V obtained in each of the above examples_COMPAnd the time is transmitted to the switch on-off period timing circuit.

It should be noted that the signals output from the input side and the output side of the error amplifying circuit are designed according to the requirements of the output of the previous stage circuit and the input of the next stage circuit, and therefore, the above examples are only for illustration and are not intended to limit the present application.

The switch on-off period timing circuit 312 is connected to the output end of the error amplifying circuit, and is configured to perform switch on-off period timing based on the error amplifying signal, and output a first conduction detection signal when the timing is over. In some specific examples, the switch on-off period timing circuit 312 may amplify the signal V based on the error_COMPAnd timing the conduction time of the switch unit, and adjusting the on-off period of the switch unit by adjusting the conduction time. In other specific examples, the switch on-off period timing circuit may further amplify the signal V based on the error_COMPTiming the on-off period time of the switch unit, and adjusting the on-off period of the switch unit by adjusting the on-off period time.

In some examples, the switch on-off period timing circuit includes a timing capacitor, and a first control circuit and a second control circuit connected to the timing capacitor and receiving the error amplified signal. Here, the circuit structure of the switch on/off period timing circuit that uses the timing capacitor to time the on interval of the switch unit is similar to the circuit structure of the time-limiting circuit that uses the timing capacitor to time the first period, and will not be described in detail here. The difference is that the timing threshold voltage set in the switch on-off period timing circuit is based on the error amplification signal V_COMPAnd is determined.

In other examples, the switch on/off cycle timing circuit includes a timing counter and a counter control circuit coupled to the timing counter and receiving the error amplified signal. Here, the circuit structure of the switch on/off period timing circuit for timing the conduction interval of the switch unit using the timer counter is similar to the circuit structure of the time limit circuit for timing the first period using the timer counter, and will not be described in detail. The difference is that the timing overtime conditions including timing threshold voltage, timer overflow condition and the like set in the switch on-off period timing circuit are based on the error amplification signal V_COMPAnd is determined. For example, theA counter control circuit in the on-off period timing circuit of the switch amplifies a signal V according to an error_COMPAnd selecting a counter with corresponding digit, and determining the timing timeout when the count of the selected counter overflows. For another example, a counter control circuit in the switch on-off period timing circuit converts the current count value of the timing counter into a voltage value, and the voltage value is compared with the error amplification signal V_COMPAnd comparing to determine the timing timeout according to the comparison result.

According to the actual design requirement, the switch on-off period timing circuit can also simultaneously comprise a timing circuit structure provided with a timing counter and a timing capacitor so as to deal with an error amplification signal V_COMPAnd outputting a first conduction detection signal based on the timing timeout signals of the two timing circuit structures by using the logic circuit structure. The logic circuit structure includes, for example, a circuit combination of one or more of the following: flip-flops, logic and gates, logic not gates, logic or gates, comparators, etc.

Based on the circuit structures shown in the above examples, the working process of the switch on-off period detection module is as follows: the time limit circuit triggers the timing of a first time interval based on the invalidity of a switch control signal of the switch unit during the disconnection of the switch unit, and the error amplification circuit amplifies an error signal between a reference signal and a feedback signal based on a preset gain and outputs an error amplification signal V during the timing_COMPThe switch on-off period timing circuit is based on the invalid trigger timing of the driving signal of the switch unit and utilizes the error amplification signal V_COMPThe timer is determined to be timed out, thereby changing the on-off period of the switching unit.

Referring to fig. 6, which is another schematic circuit diagram of the switch control device, the conduction detection unit further includes a demagnetization detection module 321, and the demagnetization detection module 321 is connected to the sampling unit and obtains a zero-crossing reference signal V_{REF_Z}A controller configured to detect a signal of a second period in the feedback signal based on the zero-cross reference signal and output the second conduction detection signal based on a detection result; wherein the second conduction detection signal is usedIndicating that the demagnetization of the inductive circuit in the power conversion unit is finished. The zero-crossing reference signal is a built-in reference signal with the voltage being zero or slightly larger than zero.

Here, taking the switching control device shown in fig. 3 and the signal waveform diagram shown in fig. 4 as an example, the inductance sensor converts the induced magnetic energy into electric energy based on the demagnetization operation of the primary winding in the transformer, and when the demagnetization operation is finished, the voltage of the feedback signal output by the conversion approaches zero. To this end, the demagnetization detecting module detects a signal of a second period in the feedback signal based on the zero-crossing reference signal.

The demagnetization detection module comprises a comparison circuit and a shielding circuit. One input end of the comparison circuit receives a zero-crossing reference signal, the other input end of the comparison circuit receives the feedback signal, and when the voltage of the feedback signal is reduced to the zero-crossing reference signal, a second conduction detection signal is output. The shielding circuit is used for comparing the zero crossing point V shown in figure 4 when the comparison circuit outputs the second conduction detection signal_ZAnd then the oscillating feedback signal is shielded to reduce false triggering of demagnetization detection.

During the switching-off period of the switching unit, under the influence of mutual inductance between the primary and secondary windings of the transformer and the electromagnetic sensor, after the demagnetization operation of the secondary winding is finished, the inductive sensor still outputs the oscillation signal generated by induction, namely the oscillation signal shown after the second time period in fig. 4. Therefore, when the comparison circuit detects the zero-crossing voltage of the feedback signal for the first time during the switching-off period of the switch unit, the output second conduction detection signal (namely, the demagnetization detection signal) triggers the shielding circuit, the shielding circuit is a timing circuit, and the overtime signal output when the timing is overtime is used for shielding the comparison circuit to output the first conduction detection signal or shielding the logic control unit to respond to the second conduction detection signal to normally conduct the switch unit.

The disconnection detecting unit 203 is coupled to a second sampling module 2012 in the sampling unit, and is configured to detect the sampling signal based on the feedback signal and output a disconnection detection signal based on a detection result.

Here, the off detection unit 203 generates a peak reference signal for detecting the on of the switching unit based on the feedback signal, performs off detection on the sampling signal, and outputs an off detection signal corresponding to the detection result.

In some embodiments, the disconnection detection unit includes a disconnection signal generation module and a peak detection module. Wherein the turn-off signal generation module receives the feedback signal and outputs a peak reference signal generated based on the feedback signal. The first input end of the peak detection module is connected with the sampling unit to obtain a sampling signal, and the second input end of the peak detection module receives the peak reference signal and is used for detecting the sampling signal based on the peak reference signal and outputting a disconnection detection signal based on a detection result.

Here, the peak detection module starts to detect the sampling signal when the switching unit is turned on. The peak detection module takes a switch control signal which is output by the logic control unit and used for controlling the switch-on of the switch unit as an enabling signal, detects a sampling signal when the enabling signal is effective, and outputs a disconnection detection signal for effective identification of the logic control unit when the level value of the sampling signal is detected to reach the level value of the peak reference signal. For example, the peak detection module detects a sampling signal when the enable signal is active, and when it is detected that a level value of the sampling signal reaches a level value of the peak reference signal, the off detection signal output by the peak detection module changes from a low level to a high level, and the logic control unit regards the high level as an active signal to output a switch control signal for turning off the switch unit. The peak detection module may also start detecting the sampling signal when receiving the time-out signal output by the time-limiting circuit. For example, the peak detection module is controlled by an enable signal, i.e., a detection sampling signal is triggered based on a time-out signal (enable signal) output by the time-limiting circuit.

In another embodiment, different from the previous embodiment, the second input terminal of the peak detection module is connected to the conduction detection unit to obtain a peak reference signal related to the feedback signal generated in the conduction detection unit.

As shown in fig. 6, the peak detection module 411 is connected to the error amplifying circuit 311 in the conduction detection unit, and uses the error amplified signal as the peak reference signal. The comparison circuit in the peak detection module compares the received peak reference signal with the sampling signal V_CSAnd outputs a disconnection detection signal.

To output the disconnection detection signal, the peak detection module at least includes a comparison circuit. The first input end of the comparison circuit receives the sampling signal, the second input end of the comparison circuit receives the peak value reference signal, and the output end of the comparison circuit outputs a disconnection detection signal obtained by comparing the voltage of the sampling signal with the voltage of the peak value reference signal.

The comparison circuit includes a comparator. The positive input end of the comparator receives a peak value reference signal, the negative input end of the comparator receives a sampling signal, and when the voltage of the sampling signal does not reach the voltage of the peak value reference signal, the comparator outputs a disconnection detection signal represented by low voltage; when the voltage of the sampling signal reaches the voltage of the peak reference signal, the comparator outputs a disconnection detection signal represented by a high voltage.

It should be noted that the disconnection detection signal output by the comparison circuit and the signal of the subsequent logic control unit are set as needed. In other examples, a negative input of the comparison circuit receives the peak reference signal and a positive input receives the sampled signal. On the basis of the above examples, the comparison circuit may further include an isolator, a latch, and the like according to the identification requirement of the subsequent logic control unit for the disconnection detection signal.

The first on detection signal, the second on detection signal, and the off detection signal output from each of the on detection unit and the off detection unit mentioned based on the above-mentioned examples are transmitted to the logic control unit.

The logic control unit is used for controlling the switch unit to be switched on/off in a DCM mode or a QR mode based on the control logics of the switch-off detection signal, the first conduction detection signal and the second conduction detection signal.

Here, in order to accommodate different loads to be connected and provide stable power supply for the loads, the timing at which the logic control unit outputs the switch control signal for conduction to the switching unit is based on the timing at which the signal is received later in the first conduction detection signal and the second conduction detection signal. Thus, when the first conduction detection signal is received later than the second conduction detection signal, the logic control unit controls the switching unit to operate in the DCM mode; and when the second conduction detection signal is received later than the first conduction detection signal, the logic control unit controls the switch unit to work in the QR mode.

For this purpose, the logic control unit at least comprises a logic and device, when two input ends of the logic and device are both at a high level, the logic and device outputs a high level signal when a first conduction detection signal and a second conduction detection signal are received; a logic circuit in the logic control unit connected to the and logic device outputs a switch control signal for turning on the switch unit based on the high level signal output from the and logic device, in other words, the switch unit performs a turn-on operation based on the switch control signal.

Please refer to fig. 7, which is a schematic diagram showing signals of the switch control device when the load side is light load, wherein the on/off period circuit of the switch in the conduction detection unit is based on the feedback signal V_FBAnd the generated error amplifying signal V_COMPAnd timing the on-off period of the switch, wherein the timing duration is longer than the duration of the demagnetization operation detected by the demagnetization detection circuit in the conduction detection unit, namely the second conduction detection signal is prior to the first conduction detection signal, and the logic control unit is based on logic and the first conduction detection signal and the second conduction detection signal so as to output a switch control signal for enabling the switch unit to be conducted. The disconnection detecting unit starts to detect a sampling signal CS sampled from an output terminal of the switching unit based on a switching control signal for turning on the switching unit, and based on a peak reference signal V generated by a feedback signal reflecting a load power supply_COMPDetecting the peak level of the sampling signal CS to determine the current I flowing through the inductor in the power conversion unit_pkAnd when the level value corresponding to the sampling signal CS is reachedDetermining the current I at the level value represented by the peak reference signal_pkThe disconnection detecting unit outputs a disconnection detection signal if the peak value of the switching signal reaches a preset peak value, and the logic control unit outputs a switching control signal for switching off the switching unit based on the disconnection detection signal.

Based on the on and off control of the switch unit by the switch control device provided in the above example, when the switch control device generates the first on detection signal after generating the second on detection signal, the switch control device corresponds to the current I flowing through the inductor in the power conversion unit_pkThe waveform of the sampling signal CS is shown in fig. 7, and this waveform example reflects that the switching power supply is in DCM mode.

Please refer to fig. 8, which is a schematic diagram showing signals in the switch control device and the switch unit when the resistance value at the load side is larger than the light load condition shown in fig. 7, wherein the on-off period circuit of the switch in the conduction detection unit amplifies the signal V by the error generated based on the feedback signal_COMPAnd carrying out on-off period timing, wherein the timing duration is less than or equal to the duration of detecting demagnetization operation by the demagnetization detection circuit in the conduction detection unit due to the power consumption of the load side becoming large, namely the second conduction detection signal is not prior to the first conduction detection signal, and the logic control unit is based on logic and the first conduction detection signal and the second conduction detection signal so as to output a switch control signal for enabling the switch unit to be conducted. The disconnection detecting unit starts to detect a sampling signal CS sampled from an output terminal of the switching unit based on a switching control signal for turning on the switching unit, and based on a peak reference signal V generated by a feedback signal reflecting a load power supply_COMPDetecting the peak level of the sampling signal CS to determine the current I flowing through the inductor in the power conversion unit_pkAnd when the level value using the sampling signal CS reaches the level value corresponding to the peak reference signal, the current I is determined_pkThe disconnection detecting unit outputs a disconnection detection signal if the peak value of the switching signal reaches a preset peak value, and the logic control unit outputs a switching control signal for switching off the switching unit based on the disconnection detection signal.

Based on the above examplesThe switch control device controls the on and off of the switch unit, when the on detection signal in the switch control device generates the first on detection signal and then generates the second on detection signal, which is equivalent to no interval between the demagnetization stage and the excitation stage of the power conversion circuit, and the current I flowing through the inductor in the power conversion unit is utilized_pkDescribes the waveform of the sampling signal CS as shown in fig. 8, which reflects that the switching power supply is in the QR mode.

The switch control device can provide stable power supply adapting to the connected load according to the change of the load side resistance value. In order to provide the above functions, the logic control unit includes, in addition to the logic and device: and the logic control unit can also comprise an inverter, a buffer and the like according to the connection configuration of the corresponding logic device. For example, the logic control unit includes: the first latch and the second latch correspondingly receive the first conduction detection signal and the second conduction detection signal, the logic AND device connected with the first latch and the second latch, and the trigger connected with the logic AND device. The first latch and the second latch respectively correspondingly latch the received first conduction detection signal and the second conduction detection signal and output corresponding latch signals, two paths of latch signals corresponding to the first conduction detection signal and the second conduction detection signal are output to two input ends of the logical AND device, and when the two input ends both correspond to the high level of the logical AND device, the logical AND device outputs a high level signal to trigger a set end of the trigger, so that the trigger outputs a switch control signal for enabling the switch unit to be switched on. In addition, the reset terminal of the flip-flop receives the off detection signal, so that the flip-flop outputs a switching control signal for turning on the switching unit when receiving the off detection signal.

On the basis of the above examples, in order to adapt to wider load side changes and provide stable power supply for the load side changes, for example, when a load with a larger resistance value is connected to the load side, the inductor, the energy storage circuit and the like in the power conversion unit need to be adapted and adjusted when the QR mode power supply is adopted, otherwise, the power supply requirement of the load side cannot be met. Examples of the accessed load include a tablet computer, a notebook computer, and the like. To this end, please refer to fig. 9, which is a circuit diagram of a conduction detection unit in a switch control device according to another embodiment. The conduction detecting unit in the switching control device further includes: and a CCM Mode switch on-off period timing module 314, connected to the logic control unit, and configured to perform CCM Mode (continuous connection Mode) switch on-off period timing when the switch unit is turned on, and output a third Conduction detection signal when the timing is overtime. The logic control unit in the switch control device also controls the switch unit to be conducted based on the first conduction detection signal, the second conduction detection signal and the third conduction detection signal. In cooperation with off control triggered by an off detection signal, in other words, the logic control unit controls the switching unit to be turned on/off in the DCM mode, the QR mode, or the CCM mode based on control logic of the off detection signal, the first on detection signal, the second on detection signal, and the third on detection signal.

Here, the CCM mode switch on-off period timing module performs CCM mode switch on-off period timing by using a switch control signal for turning on the switch unit as a trigger signal. The CCM mode switch on-off period timing takes the switch unit on as a timing starting point, takes a fixed timing duration as a timing end point, and outputs a third conduction detection signal when the timing is overtime. And the set timing duration is less than the maximum value of the on-off period of the switch in the QR mode.

Here, the timing circuit in the CCM mode switch on-off period timing module is similar to the aforementioned switch on-off period timing circuit. The timing circuit in the CCM mode switch on-off period timing module performs a reset operation based on a signal generated later in the second conduction detection signal and the first conduction detection signal during timing, which is different from the circuit structure of the switch on-off period timing circuit. For example, the CCM mode switch on-off period timing module further receives a logic signal output by a logic and device in the logic control module, and performs a reset operation based on the logic signal.

Taking the CCM mode switch on-off period timing module as an example, the timing capacitor is controlled by the first control circuit of the timing capacitor based on the switch control signal for turning on the switch unit, so that the voltage of one electrode approaches to a reference voltage for timing operation, if the CCM mode switch on-off period timing module does not receive the logic signal output by the logic and device in the logic control module all the time in the whole timing period, when the voltage of the electrode reaches the corresponding reference voltage, the comparison result output by the comparison circuit in the CCM mode switch on-off period timing module is changed from one level state to another level state, the state change indicates timing timeout, and the signal output by the comparison circuit for describing timing timeout is the third conduction detection signal. And if the CCM mode switch on-off period timing module receives a logic signal output by a logic AND device in the logic control module before timing is overtime, the second control circuit of the timing capacitor controls the timing capacitor to execute reset operation based on the logic signal, so that the comparison result output by the comparison circuit does not represent timing overtime.

Taking the CCM mode switch on-off period timing module as an example, including a timing counter, the first control circuit of the timing counter starts to control the timing counter based on the switch control signal for turning on the switch unit, so that the timing counter approaches to a counting threshold value for performing timing operation, if the CCM mode switch on-off period timing module does not receive the logic signal output by the logic and device in the logic control module all the time in the whole timing period, when the counting value of the timing counter reaches the counting threshold value, the digital-to-analog conversion circuit in the CCM mode switch on-off period timing module respectively converts the counting value and the counting threshold value into voltage signals in real time and inputs the voltage signals to the two input ends of the comparison circuit, the comparison result output by the comparison circuit is converted from one level state to another level state, and the state change indicates timing timeout, and the signal which is output by the comparison circuit and used for describing the timing timeout is a third conduction detection signal. If the CCM mode switch on-off period timing module receives a logic signal output by a logic AND device in the logic control module before timing timeout, the reset circuit of the timing counter controls the timing counter to execute reset operation based on the logic signal, so that a comparison result output by the comparison circuit does not represent timing timeout.

Correspondingly, the logic control unit further includes a logic or device based on the foregoing examples, two input ends of the logic or device respectively receive the logic signal output by the logic and device and the third conduction detection signal, and the logic or device controls the flip-flop to output the switch control signal for turning on the switch unit based on the first received logic signal or the third conduction detection signal. When the third conduction detection signal reaches the logic control unit before the logic signal, it indicates that the switch unit is controlled to be conducted before the demagnetization operation of the power conversion unit is finished, in other words, the power conversion unit is in a CCM mode; when the logic signal reaches the logic control unit before the third conduction detection signal, it indicates that the switching unit is controlled to be conducted after the demagnetization operation of the power conversion unit is finished, in other words, the power conversion unit is in the DCM mode or the QR mode.

Each of the above examples of the switching control apparatus is provided with a power supply unit for supplying power to the active devices in the phase switching control apparatus. The active devices include, for example, a current source for generating a constant voltage signal, a control circuit for outputting a capacitor for charging a signal, an error amplifier, and the like. The power supply unit is coupled to a power bus to store electrical energy. In some examples, the power supply unit may be configured with a separate energy storage module and a charging module, wherein one end of the charging circuit is connected to the power supply bus, the other end of the charging circuit is connected to the energy storage module, and the other end of the energy storage module is connected to a VCC port in the switch control device to provide internal power supply. In other examples, the power supply unit may obtain power using an existing circuit configuration of the switching control device. For example, the power supply unit is connected to the inductive sensor, and stores energy by the electrical signal output by the inductive sensor to provide internal power supply. For this purpose, the power supply unit comprises an energy storage module and a unidirectional conducting module. The energy storage module is connected with the output end of the inductance sensor and used for providing power for the interior of the switch control device by the electric signal output by the inductance sensor. The unidirectional conduction module is arranged on a line between the output end of the inductive sensor and the energy storage module. The energy storage module comprises a capacitor and a charging circuit, wherein the charging circuit is connected between the output end of the inductive sensor and one polar plate of the capacitor, the other polar plate of the capacitor is connected with the VCC end, and the charging circuit is provided with the single conduction module. Here, the unidirectional conducting module includes a diode, for example.

Based on the above examples and with reference to fig. 9 and fig. 10, when the switching power supply provided by the present application is connected to a load (such as a tablet computer) with a large resistance and charges the load, the operation process of any on-off cycle of the switch is as follows: during the switching-off period of the switching unit, a switching on-off period detection module in the conduction detection unit performs error amplification processing on a feedback signal acquired from the inductive sensor in a first period and a reference signal, performs timing on the conduction period of the switching unit based on the generated error amplification signal, and outputs a first conduction detection signal when the timing is overtime. Meanwhile, the demagnetization detection module in the conduction detection unit also acquires a feedback signal of the self-inductance sensor, detects the first zero-crossing moment of the feedback signal based on the zero-crossing reference signal and outputs a second conduction detection signal, and in order to prevent multiple zero crossings caused by subsequent vibration of the feedback signal, the demagnetization detection module shields the feedback signal based on the output second conduction detection signal, so that the demagnetization detection module outputs the first second conduction detection signal in a second time period from the disconnection of the switch unit to the shielding. And during the disconnection period of the switch unit, the CCM mode switch on-off period timing module in the conduction detection unit starts to carry out the switch on-off period of the CCM mode. The logic control unit is provided with a logic AND logic OR device, wherein two input ends of the logic AND device respectively receive a first conduction detection signal and a second conduction detection signal, and the logic OR device respectively receives a logic signal and a third conduction detection signal output by the logic AND device. According to the power supply condition of the load side reflected by the feedback signal, the time spent by the demagnetization detection module for detecting the zero-crossing moment of the feedback signal and/or the timing time of the switch on-off period detection module in the CCM mode are/is longer than the timing time of the switch on-off period timing module in the CCM mode. During the conduction period of the switch unit, the electric signal in the power supply bus is transmitted to the power conversion unit, the inductance circuit in the power conversion unit enters the excitation operation, and the energy storage circuit mainly maintains the load power supply. The switch control signal is also output to a disconnection detection unit, the disconnection detection unit detects a sampling signal output from the switch unit to the power conversion unit by taking the error amplification signal as a peak reference signal, and when the voltage of the sampling signal reaches the voltage of the peak reference signal, the disconnection detection signal is output to the logic control unit; a flip-flop in the logic control unit outputs a switching control signal for turning off the switching unit based on the off detection signal. During the off period of the switching unit, the inductance circuit in the power conversion unit enters into demagnetization operation, and an electric signal generated by the demagnetization operation is output to the load side and the energy storage circuit, wherein the energy storage circuit carries out energy storage operation so as to maintain the power supply of the load in the later period of the push operation and the excitation operation period in the next switching period. The switch control device controls the on/off of the switch unit based on the above-described control process, so that the electrical signal in the inductance circuit in the power conversion unit exhibits a waveform of the sampling signal CS as shown in fig. 10 in the CCM mode.

As the electric charge stored in the load increases, the resistance value thereof gradually decreases, and the detection of the on-off period, the peak detection, and the like of the switch by the switch control device based on the feedback signal also changes. In a certain switching period, during the switching-off period of the switching unit, when the switching-on and switching-off period detection module outputs a first conduction detection signal and the demagnetization detection module outputs a second conduction detection signal, and the first conduction detection signal is output to the logic control unit before the second conduction detection signal, the CCM mode switch on and off period timing module does not time out yet, a logic and device in the logic control unit outputs a logic signal represented by a high level when receiving the first conduction detection signal and the second conduction detection signal, the logic or device outputs the high level signal to the trigger based on the logic signal, the trigger outputs a switching control signal for enabling the switching unit to be switched on, and the switching control signal is also output to the CCM mode switch on and off period timing module and the switching-off detection unit at the same time; the CCM mode switch on-off period timing module resets and times based on the switch control signal; the disconnection detection unit detects a sampling signal output from the switching unit to the power conversion unit by taking the error amplification signal as a peak reference signal, and outputs a disconnection detection signal to the logic control unit when the voltage of the sampling signal reaches the voltage of the peak reference signal; a flip-flop in the logic control unit outputs a switching control signal for turning off the switching unit based on the off detection signal. Based on the above control logic, the switching of the switching unit causes the inductive circuit in the power conversion unit to immediately enter the excitation operation at the end of the demagnetization operation, which causes the waveform of the inductive circuit in the power conversion unit to be as the waveform of the sampling signal CS shown in fig. 8, and the switching power supply to be in the QR mode.

When the load charging is finished, the resistance value of the load is continuously reduced, which is equivalent to that the switching power supply is in a light load state, in a certain switching period, when the switching on-off period detection module outputs a first conduction detection signal during the switching off period of the switching unit, and the demagnetization detecting module outputs a second conduction detecting signal, and when the first conduction detecting signal is later than the second conduction detecting signal and is output to the logic control unit, the CCM mode switch on-off period timing module does not time out, a logic AND device in the logic control unit outputs a logic signal represented by a high level when receiving a first conduction detection signal and a second conduction detection signal, the logic OR device outputs the high level signal to a trigger based on the logic signal, the trigger outputs a switch control signal for enabling the switch unit to be conducted, the switch control signal is also simultaneously output to a CCM mode switch on-off period timing module and a disconnection detection unit; the CCM mode switch on-off period timing module resets and times based on the switch control signal; the disconnection detection unit detects a sampling signal output from the switching unit to the power conversion unit by taking the error amplification signal as a peak reference signal, and outputs a disconnection detection signal to the logic control unit when the voltage of the sampling signal reaches the voltage of the peak reference signal; a flip-flop in the logic control unit outputs a switching control signal for turning off the switching unit based on the off detection signal. Based on the above control logic, the on/off of the switch unit makes the inductor circuit in the power conversion unit have a time gap interval after the demagnetization operation is finished until the on/off period of the switch is timed, so that the waveform of the inductor circuit in the power conversion unit is as the waveform of the sampling signal CS shown in fig. 7, and the switching power supply is in the DCM mode.

As can be seen from the above example, the switching power supply can adaptively match different loads connected, thereby providing stable power supply for the loads matched with the power supply.

In the conduction detection unit provided by the present application, the reference signal received by the error amplification circuit used in the conduction detection unit can be provided by a power supply inside the switch control device, which is generally configured based on the charging requirements of the switch power supply and the load thereof at the time of factory shipment. When the reference signal provides a fixed level, the error amplifying circuit performs switching period timing based on the level difference between the feedback signal and the reference signal, the timing is timed out, the output first conduction detection signal influences the conduction time of the switching unit, and when the switching unit executes the conduction operation period based on the first conduction detection signal, the power supply output by the power conversion unit to the load side is changed at any time. Specific variations are exemplified by: when the power supply output by the power conversion unit is lower than the power supply corresponding to the reference signal, the conduction time determined by the conduction detection unit based on the error amplification signal is longer, so that the power supply output by the power conversion unit is increased, namely the power supply level output by the power conversion unit is close to the power supply level corresponding to the reference signal. When the power supply level output by the power conversion unit is close to the power supply level corresponding to the reference signal, the difference between the feedback signal received by the error amplification circuit and the reference signal is reduced, so that the conduction time determined by the conduction detection unit based on the error amplification signal is shortened, the power supply output by the power conversion unit is reduced, namely the power supply output by the power conversion unit is reducedThe difference between the power level and the power level corresponding to the reference signal is increased. One of the reasons for the above-mentioned jitter and power supply instability is that: the error amplifying signal V provided by the error amplifying circuit for keeping the load power supply within the normal power supply range is caused by the resistance value change of the load_COMPNot matching the difference between the feedback signal input by the error amplifying circuit and the reference signal.

As can be seen from the above examples, when a load that is not suitable for factory configuration is connected to a switching power supply that supplies power using a fixed reference signal, or when the resistance value of the connected load changes, the switching power supply outputs a power supply output that is lower than normal power supply and has large jitter according to the change of the resistance value. Such a situation that stable power supply cannot be provided within a normal range and output power supply jitter is large is also reflected in a situation that an external alternating-current power supply connected to the switching power supply is not matched with factory configuration.

In order to solve the above-mentioned defect, this application still provides an error amplifier circuit. The error amplifying circuit is not only applicable to the switching power supply examples described in the foregoing of the present application, but also applicable to a switching power supply configured to provide any single mode or at least two other modes.

Please refer to fig. 11, which is a schematic circuit diagram of the error amplifier circuit according to an embodiment. The error amplifier circuit comprises a first input 532 and a second input 531 for receiving a reference signal and a feedback signal, respectively. The first input terminal may be a positive input terminal of the error amplifier circuit, and the second input terminal is a negative input terminal of the error amplifier circuit. According to the internal circuit structure of the error amplifier circuit, the first input terminal may also be a negative input terminal of the error amplifier circuit, and the second input terminal is a positive input terminal of the error amplifier circuit. The output 533 of the error amplifying circuit outputs an error amplified signal.

To this end, the error amplifying circuit includes: error amplification unit 510, compensation unit 520. Herein, the error amplifying unit and the compensating unit may also be referred to as an error amplifying sub-circuit and a compensating sub-circuit.

The error amplifying unit 510 has a positive input terminal, a negative input terminal, and an output terminal. The positive input terminal of the error amplifying unit 510 obtains an integrated signal, and the negative input terminal is connected to the first input terminal of the error amplifying circuit to obtain one of a reference signal and a feedback signal.

Wherein the integration signal is generated based on the other of the reference signal and the feedback signal. Here, the integrated signal is provided by the compensation unit 520, which will be described in detail later.

The feedback signal is used for reflecting that the switching power supply where the switching control device is located supplies power to the load provided by the load side. In some examples, the feedback signal may come from an inductive sensor as shown in the previous examples. In other examples, the feedback signal is derived based on a voltage division of the power output from a terminal of the switching power supply connected to the load. In still other examples, the feedback signal is generated based on averaging an electrical signal in an inductive circuit in the power conversion unit.

The error amplifying unit is used for amplifying an error between the two signals received by the positive input end and the negative input end based on a preset gain and outputting an error amplified signal.

In some examples, the positive input terminal of the error amplifying unit is connected to the second input terminal of the error amplifying circuit through the compensation unit, and the negative input terminal of the error amplifying unit is connected to the first input terminal of the error amplifying circuit. Under the condition that the first input end receives the reference signal and the second input end receives the feedback signal, the negative input end of the error amplification unit receives the reference signal, and the positive input end of the error amplification unit receives the integrated signal obtained after the compensation unit processes the feedback signal.

In other examples, the positive input terminal of the error amplifying unit is connected to the second input terminal of the error amplifying circuit through the compensation unit, and the negative input terminal of the error amplifying unit is connected to the first input terminal of the error amplifying circuit. Under the condition that the first input end receives the feedback signal and the second input end receives the reference signal, the negative input end of the error amplification unit receives the feedback signal, and the positive input end of the error amplification unit receives the integrated signal obtained after the compensation unit processes the reference signal.

Based on the connection manner provided by any of the above examples, the error amplifying unit amplifies an error between the two signals received by the positive input terminal and the negative input terminal based on a preset gain and outputs an error amplified signal, where the error amplified signal is output through an output terminal of the error amplifying circuit. For example, the error amplification signal is used as a reference signal for timing timeout and output to the switch on-off period detection module.

In order to implement the error amplification unit to perform error amplification processing on the two received signals with a preset gain, the error amplification unit includes an error amplifier and a gain amplification module. Referring to fig. 12, the positive and negative input terminals of the error amplifier 5111 correspond to the positive and negative input terminals of the error amplifying unit. The gain amplification module comprises: a first resistive device(s) connecting the negative input terminal and the first input terminal, such as resistor R1; and a second resistive device(s) such as resistor R2 disposed between the negative input and output of the error amplifier. Wherein the ratio of the second resistive device(s) to the first resistive device(s) is used to represent the gain of the error amplification unit.

To effectively solve the foregoing problem, the error amplifying circuit further includes a compensation unit 520, which receives the other of the reference signal and the feedback signal from the second input 531 of the error amplifying circuit, and is connected to the positive input of the error amplifying unit 510, for performing compensation processing on the fed-back error amplifying signal and performing integration processing on the fed-back error amplifying signal and the signal obtained from the first input, so as to obtain the integrated signal. The integrated signal is used for compensating the error amplification unit so as to weaken the power supply with deviation, which is output to the load side by the switching power supply based on external circuit change.

Here, the compensation unit 520 is configured to compensate for a power supply deviation between an error amplification signal for assisting the load side in stabilizing power supply and a power supply signal of the actual load side reflected by the feedback signal. Wherein, the compensation processing mode comprises: to counteract unmatched supply offsets in the feedback signal or to compensate for unmatched reference offsets in the reference signal.

The external circuit comprises a load circuit connected to the load side and/or an external alternating current power supply.

Please refer to fig. 13, which is a circuit diagram of the compensation unit according to an embodiment. The compensation unit includes a gain compensation module 5201 and a signal integration module 5202.

The gain compensation module 5201 is connected to the output end of the error amplification unit, and is configured to convert the error amplified signal fed back from the output end into a compensation signal based on the gain.

Here, to obtain a deviation between the feedback signal reflected by the error amplified signal and the reference signal, the gain compensation module performs an inverse process on the error amplified signal based on the gain to obtain a compensation signal. The gain compensation module at least comprises a feedback compensation circuit, which is arranged on a line between the output end of the error amplification unit and the signal integration module based on the gain and is used for dividing the fed-back error amplification signal based on the gain and outputting the compensation signal. For example, the feedback compensation circuit comprises a third resistive device(s) connected between the positive input terminal and the output terminal of the error amplification unit, and a fourth resistive device(s) connected between the second input terminal and the positive input terminal of the error amplification unit. The ratio of the resistances of the third resistive device(s) and the fourth resistive device(s) corresponds to the ratio of the second resistive device(s) and the first resistive device(s) in the foregoing example, so that the compensation signal output by the feedback compensation circuit is a deviation signal between the feedback signal and the reference signal.

To reduce various drawbacks, such as jitter variations of the feedback signal, and/or to reflect average signal deviations, the gain compensation module further comprises a buffer circuit. The buffer circuit is arranged on the feedback compensation circuit and used for buffering the error amplification signal fed back in at least one switching period, so that the feedback compensation circuit outputs a compensation signal reflecting the average value of the error amplification signal.

In some examples, the buffer circuit includes a buffer device (group). Wherein the buffer device comprises a follower or buffer gate (BUF). For example, the gain compensation module includes: a resistor R5 connected to the output terminal of the error amplifying unit, a buffer gate connected to the resistor R5, a resistor R4 connected to the buffer gate and the positive input terminal of the error amplifying unit, and a resistor R3 connected between the second input terminal and the positive input terminal of the error amplifying unit. The feedback compensation circuit reflects the gain of the error amplification unit by using the parameters of the third resistive device (group), the fourth resistive device (group) and the buffer device, and the output compensation signal V_AAccording to the formula:

wherein A is_VThe gain of the error amplification unit is indicated. Amplifying the signal V due to error_COMPBased on the fact that the error signal between the signals received by the two input ends of the error amplification unit is amplified by A_VThe gain is doubled, so that the compensation signal V_ACorresponding to the error signal between the signals received by the two input ends of the error amplifying unit.

In other examples, the buffer circuit includes a filter device(s). Wherein the filter device comprises a capacitor for providing an average signal of the error amplified signal over a number of switching periods. For example, the gain compensation module includes: the resistor R5 is connected with the output end of the error amplification unit, the capacitor with one polar plate connected with the resistor R5 and the other polar plate grounded, the buffer gate connected with the resistor R5, the resistor R4 connected with the buffer gate and the positive input end of the error amplification unit, and the resistor R3 connected between the second input end and the positive input end of the error amplification unit. For this purpose, the feedback compensation circuit reflects the gain of the error amplification unit by using the parameters of the third resistive device(s), the fourth resistive device(s), the capacitor, and the buffer device, and outputs a compensation signal V_AAccording to the formula:

wherein A is_VWhich represents the gain of the error amplification unit,

representing the average signal of the error amplified signal. Amplifying the signal due to error

Is based on the mean value of the error signal between the signals received at the two inputs of the error amplification unit, amplified A_VThe gain is doubled, so that the compensation signal V_ACorresponding to the average value of the error signals between the signals received by the two input ends of the error amplifying unit.

The compensation signal and the signal received by the second input end of the error amplification circuit are respectively input to two input ends of a signal integration module for integration processing, and the obtained integrated signal is transmitted to an error amplification unit.

In connection with the aforementioned example, in case that the first input terminal of the error amplifying circuit receives the reference signal and the second input terminal receives the feedback signal, the signal integration module comprises a subtraction integration circuit connected between the second input terminal and the positive input terminal of the error amplifying unit for subtracting the compensation signal from the acquired feedback signal to obtain an integrated signal. The subtraction integration circuit comprises a subtracter, a buffer circuit and the like.

Referring to fig. 14, which is a circuit diagram of an error amplifier circuit in one embodiment, a subtractor in the subtraction integration circuit 6202 is disposed between a fourth resistive device (group) 6201a in the gain compensation module and a positive input terminal of the error amplifier unit 5111. Wherein the feedback signal V_FBThe compensation signal is input to one input terminal of the subtraction integration circuit 6202 through the fourth resistive device (group) 6201a, and the compensation signal is input to the other input terminal of the subtraction integration circuit through a buffer circuit and the third resistive device (group) 6201b, and the subtraction integration circuit 6202 performs difference processing on the two signals to obtain an integrated signal and outputs the integrated signal to the positive input terminal of the error amplification unit 5111. Error amplifierThe large unit 5111 combines the integrated signal at the positive input terminal and the reference signal V at the negative input terminal_ref1Performing error amplification processing to output the error amplification signal V_COMP. Because the compensation unit is used for offsetting the signal deviation between the feedback signal and the reference signal, the error amplification signal is not interfered by the feedback signal, and the defects caused by the fact that the reference signal is a fixed signal are effectively eliminated.

In the case that the second input terminal of the error amplifying circuit receives the reference signal and the first input terminal of the error amplifying circuit receives the feedback signal, the signal integration module includes an addition integration circuit, connected between the second input terminal and the positive input terminal of the error amplifying unit, for subtracting the compensation signal from the obtained reference signal to obtain an integrated signal. The subtraction integration circuit comprises a lead, a buffer circuit and the like, wherein the lead is connected with the third resistive device (group) and the fourth resistive device (group).

Referring to fig. 15, which is a circuit structure diagram of an error amplifier circuit in an embodiment, a line between a fourth resistive device (group) 6201a and a positive input end of an error amplifier unit 5111 in a gain compensation module is conducted with a line where a third resistive device (group) 6201b is located; or a line between the fourth resistive device (group) 6201a and the positive input end of the error amplifying unit 5111 in the gain compensation module is connected to the third resistive device (group) 6201b through an adder. Wherein the reference signal V_refThe compensation signal and the buffer circuit and the fourth resistive device(s) are combined into an integrated signal through the conducting line (or adder) 7202, and the integrated signal is output to the positive input terminal of the error amplifying unit 5111. The error amplifying unit 5111 combines the integrated signal of the positive input terminal and the feedback signal V of the negative input terminal_FBAnd carrying out error amplification processing to output the error amplification signal. And the compensation unit is used for offsetting the signal deviation between the feedback signal and the reference signal, so that the error amplification signal is not interfered by the feedback signal, and the defects caused by the fact that the reference signal is a fixed signal are effectively eliminated.

In combination with the example in the aforementioned switching power supply and the example in the error amplification circuit, the present application also provides a switching power supply including the error amplification circuit as illustrated in any one of fig. 11 to 15. Wherein the switching power supply includes: the power conversion device comprises a rectifying unit, a switching unit, a power conversion unit and a switching control device.

The rectifying unit, the switching unit and the power converting unit are respectively the same as or similar to the circuit structures and the operation processes of the rectifying unit, the switching unit and the power converting unit in the switching power supply shown in fig. 1, and detailed description thereof is omitted.

For example, the rectification unit includes a full-wave rectification bridge. The switch unit comprises a power tube. The power conversion unit comprises an inductance circuit and an energy storage circuit; wherein, the inductance circuit includes: the primary winding is connected to the power supply bus and the switch control device; the secondary winding is coupled with the primary winding and connected to the power supply bus and provides a power supply terminal on a load side; the tank circuit is connected between the power supply bus and a power supply terminal.

The switch control device includes: the device comprises a load feedback unit, a conduction detection unit, a disconnection detection unit and a logic control unit. The load feedback unit, the disconnection detection unit, and the logic control unit are the same as or similar to the circuit structures and the operation processes of the load feedback unit, the disconnection detection unit, and the logic control unit in the switching control device shown in fig. 3, and detailed description thereof is omitted.

The conduction detection unit includes an error amplification circuit as shown in fig. 11. According to the circuit structure in the error amplifying circuit, a first input end of the error amplifying circuit can be connected with a load feedback unit, and a second input end of the error amplifying circuit receives a reference signal; or, a first input end of the error amplifying circuit receives the reference signal, and a second input end of the error amplifying circuit is connected with the load feedback unit.

Taking the circuit structure inside the error amplifying circuit as an example as shown in fig. 11, the first input end of the error amplifying circuit receives a reference signal, the second input end of the error amplifying circuit is connected with the load feedback unit, the output end of the error amplifying circuit is connected with the switch on-off period detection module in the conduction detection unit, the switch on-off period detection module utilizes the error amplifying signal output by the error amplifying circuit as a timing reference signal, and the conduction duration of the switch unit is timed. The switch on-off period detection module outputs a first conduction detection signal when the timing is overtime. The switch on-off period detection module can adjust the on-off period of the switch unit by adjusting the conduction duration.

The conduction detection unit can also comprise: the module comprises a demagnetization detection module and/or a CCM mode switch on-off period timing module. The demagnetization detection module is used for outputting a second conduction detection signal when the demagnetization of the inductance circuit in the power conversion unit is finished. The CCM mode switch on-off period timing module is used for carrying out CCM mode timing when the switch unit is switched off and outputting a third conduction detection signal when the timing is overtime.

The operation of the switching power supply in different modes is exemplified by the aforementioned fig. 7, 8 and 10 and the corresponding description, and will not be described in detail here.

Please refer to fig. 16, which is a flowchart illustrating a method for generating an error amplified signal according to the present application. The generation method is also used for an error amplification circuit.

In step S110, the error amplifying circuit obtains a reference signal and a feedback signal; the feedback signal is used for reflecting that the switching power supply where the switching control device is located supplies power to the load provided by the load side.

In step S120, the error amplifying circuit amplifies an error between an integration signal and one of the reference signal and the feedback signal based on a predetermined gain, and outputs an error amplified signal. Wherein the integrated signal is obtained by integrating the error amplified signal after compensation processing with the other signal of the reference signal and the feedback signal; wherein the integration signal is used to compensate the error amplification signal to attenuate a biased supply of the switching power supply to the load side output based on external circuit variations.

Here, the error amplifying circuit acquires the feedback signal by being connected to a load feedback unit. The error amplifying circuit comprises a set gain, and the error amplifying circuit converts the fed-back error amplifying signal into a compensation signal based on the gain.

The error amplifying circuit buffers an error amplifying signal fed back by the switching power supply in at least one switching period to output a compensation signal reflecting an average value signal of the error amplifying signal.

The error amplifying circuit performs deviation weakening integration on the compensation signal and one signal of the reference signal and the feedback signal to obtain the integrated signal, and performs error amplification processing on the integrated signal and the other signal of the reference signal and the feedback signal to output an error amplified signal.

Wherein, in some examples, referring to fig. 15, the error amplification circuit adds the acquired reference signal and the compensation signal to obtain the integrated signal based on a differential manner of the integrated signal and the reference signal.

In other examples, referring to fig. 14, the error amplification circuit subtracts the compensation signal from the acquired feedback signal to obtain the integrated signal based on a difference between the integrated signal and the feedback signal.

Please refer to fig. 17, which is a flowchart illustrating a control method of the switch control apparatus according to the present application, wherein the control method can be executed by the switch control apparatus. The switch control device enables the power conversion unit to provide stable power supply for the load by changing the electric signal in the power conversion unit connected with the power supply bus.

In step S210, the switch control device obtains a feedback signal reflecting the load-side power supply signal, and samples the induced signal in the power conversion unit.

In step S220, the switching control means performs the steps in the method of generating an error amplified signal as described in the aforementioned steps S110 to S120.

In step S230, the switch control device performs conduction detection based on the error amplification signal, and controls a switch unit in the switch control device to conduct according to a detection result; or the sampling signal is detected, and the switch unit in the switch control device is controlled to be switched off based on the detection result.

The above steps can be executed based on the above examples of the switch control device, and are not described in detail here.

The switch control device provided by the application adjusts the on-off time of the switch unit based on the feedback signal for reflecting the power supply of the load side, so that the switch power supply to which the switch control device belongs stably works in a plurality of modes, particularly in a plurality of modes including a QR mode, and therefore the adaptive stable power supply of the changed load is realized.

The error amplification circuit provided by the application utilizes the mode of compensating the error signal between feedback signal and the reference signal, effectively eliminates the mismatching relation between the error amplification signal that actual feedback signal and switching control device required when working steadily, has realized that the voltage deviation between feedback signal and the reference signal is irrelevant with the stable interval of error amplification signal, effectively eliminates from this mismatching relation.

The above embodiments are merely illustrative of the principles and utilities of the present application and are not intended to limit the application. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present application. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical concepts disclosed in the present application shall be covered by the claims of the present application.

Claims

1. A switch control device for controlling the on-off of a switch unit, wherein the switch unit is electrically connected between a power supply bus and a power conversion unit, the power conversion unit is used for providing stable power supply for a load by means of an intermittent electrical signal generated by the switch unit, wherein the power conversion unit comprises an inductance circuit for converting the intermittent electrical signal into consideration of the power supply of the load and the energy storage of an energy storage circuit, and the switch control device comprises:

the sampling unit is coupled with the power conversion unit and is used for sampling the inductive circuit and respectively outputting a feedback signal for reflecting the output power supply of the inductive circuit to a load side and a sampling signal for reflecting the current peak value in the inductive circuit;

the conduction detection unit is coupled with the sampling unit and used for respectively detecting the feedback signals in different time periods and outputting a first conduction detection signal and a second conduction detection signal based on each detection result;

a disconnection detection unit coupled to the sampling unit, for detecting the sampling signal based on the feedback signal and outputting a disconnection detection signal based on a detection result;

and the logic control unit is connected with the conduction detection unit and the disconnection detection unit and is used for controlling the switch unit to be switched on/off in a DCM (discontinuous conduction mode) or a QR (quick response) mode based on the control logics of the disconnection detection signal, the first conduction detection signal and the second conduction detection signal.

2. The switching control device according to claim 1, wherein the sampling unit includes:

the first sampling module is coupled to the inductive circuit and used for obtaining a feedback signal reflecting load power supply based on a power supply signal output to a load side by the inductive circuit; and

the second sampling module is electrically connected with an output end of the inductive circuit and used for sampling a current peak value flowing through the inductive circuit to obtain the sampling signal.

3. The switching control device of claim 2, wherein the first sampling module comprises:

the inductive sensor is coupled to an inductor which is used for generating a current peak value of power supply output to a load side in the inductive circuit so as to output an electric signal for reflecting the power supply of the load side;

and the voltage division circuit is arranged on a line between the inductance sensor and the reference voltage terminal and used for outputting the feedback signal based on the electric signal output by the inductance sensor.

4. The switching control device according to claim 3, further comprising a power supply unit for providing an internal power supply based on the electric signal output from the inductance sensor.

5. The switching control device according to claim 4, wherein the power supply unit includes:

the energy storage module is connected with the output end of the inductive sensor and used for providing power supply for the interior of the switch control device by virtue of the electric signal output by the inductive sensor;

and the unidirectional conduction module is arranged on a circuit between the output end of the inductive sensor and the energy storage module.

6. The switching control device of claim 2, wherein the second sampling module comprises: and the sampling circuit is connected between the output end of the inductor which generates the current peak value based on the discontinuous electric signal in the inductance circuit and the reference voltage terminal and outputs the sampling signal.

7. The switch control device according to claim 1, wherein the conduction detection unit includes:

the switch on-off period detection module is connected with the sampling unit and acquires a reference signal, and is used for detecting a signal in a first time period in the feedback signal based on the reference signal and outputting a first conduction detection signal based on a detection result; the first conduction detection signal is used for adjusting the on-off period of the switch unit;

the demagnetization detection module is connected with the sampling unit, acquires a zero-crossing reference signal, is used for detecting a signal of a second time interval in the feedback signal based on the zero-crossing reference signal, and outputs a second conduction detection signal based on a detection result; the second conduction detection signal is used for indicating that the demagnetization of the inductor in the power conversion unit is finished.

8. The switching control device of claim 7, wherein the switch on-off period detection module comprises:

the first input end of the error amplification circuit is connected with the sampling unit to obtain a feedback signal, and the second input end of the error amplification circuit receives the reference signal and outputs an error amplification signal obtained based on the feedback signal and the reference signal;

the switch on-off period timing circuit is connected with the output end of the error amplification circuit and is used for carrying out switch on-off period timing based on the error amplification signal and outputting a first conduction detection signal when the timing is overtime;

the time limiting circuit is connected with the error amplifying circuit and used for timing a first period of time based on the disconnection operation of the switch unit and outputting an overtime signal when the timing is overtime; wherein the time-out signal is used for limiting the error amplification circuit to receive the feedback signal.

9. The switching control device according to claim 8, wherein the error amplification circuit comprises:

an error amplification sub-circuit having a positive input terminal, a negative input terminal, and an output terminal; wherein the negative input terminal obtains one of the reference signal and the feedback signal from a first input terminal of the error amplifying circuit;

and the compensation sub-circuit is connected with the positive input end and the output end of the error amplification sub-circuit, and is used for performing feedback compensation processing on the error amplification signal output by the error amplification circuit based on the gain of the error amplification circuit to obtain a compensation signal, and integrating the compensation signal with the other signal of the reference signal and the feedback signal and transmitting the compensation signal to the input end of the error amplification unit.

10. The switching control device of claim 8, wherein the switch on-off cycle timing circuit comprises:

the timing capacitor and a charge-discharge circuit are connected with the timing capacitor and receive the error amplification signal; and/or the presence of a gas in the gas,

the timing counter and a counter control circuit which is connected with the timing counter and receives the error amplification signal.

11. The switch control device according to claim 1, wherein the disconnection detecting unit includes:

and the first input end of the peak detection module is connected with the sampling unit to obtain a sampling signal, and the second input end of the peak detection module receives a peak reference signal generated based on the feedback signal, is used for detecting the sampling signal based on the peak reference signal and outputting a disconnection detection signal based on the detection result.

12. The switching control device of claim 11, wherein the second input terminal of the peak detection module is connected to the conduction detection unit to obtain a peak reference signal related to the feedback signal generated in the conduction detection unit.

13. The switching control device of claim 11, wherein the peak detection module comprises: and the comparison circuit is provided with a first input end for receiving the sampling signal, a second input end for receiving the peak value reference signal, and an output end for outputting a disconnection detection signal obtained by comparing the voltage of the sampling signal with the voltage of the peak value reference signal.

14. The switch control device according to claim 1, wherein the conduction detection unit includes: the CCM mode switch on-off period timing module is connected with the logic control unit and used for carrying out CCM mode switch on-off period timing when the switch unit is switched on and outputting a third switching-on detection signal when the timing is overtime;

the logic control unit further receives the third conduction detection signal, and is configured to control the switch unit to be turned on/off in a DCM mode, a QR mode, or a CCM mode based on the control logic of the turn-off detection signal, the first conduction detection signal, the second conduction detection signal, and the third conduction detection signal.

15. The switch control device of claim 14, wherein the CCM mode switch on-off period timing module further performs a reset operation based on a later generated one of the second conduction detection signal and the first conduction detection signal during timing.

16. A switching power supply, comprising:

the rectifying unit is connected with an external alternating current power supply and is used for rectifying the connected alternating current and outputting the rectified alternating current to the power supply bus;

the switch unit is connected to the power supply bus and controlled to be switched on/off;

the power conversion unit is connected with the switch unit and used for providing stable power supply for a load by virtue of an intermittent electric signal generated by the switch unit, wherein the power conversion unit comprises an energy storage circuit and an inductance circuit which is used for converting the intermittent electric signal into consideration of power supply of the load and energy storage of the energy storage circuit;

a switch control device as claimed in any one of claims 1 to 15.