CN210693791U - A switching power supply circuit, semiconductor chip and power supply device - Google Patents

Abstract

The embodiment of the utility model discloses a switching power supply circuit, a semiconductor chip and a power supply device, comprising: an overcurrent protection circuit, an electromagnetic interference EMI filter circuit, an input rectification filter circuit, a main conversion circuit, a voltage feedback circuit, and a pulse width modulation PWM control circuit. A circuit and a secondary synchronous rectification circuit; the main conversion circuit includes the first MOS transistor and a flyback transformer; the secondary synchronous rectification circuit includes a second MOS transistor. By implementing the embodiments of the present invention, the efficiency of the switching power supply can be improved, the loss of the diode in the circuit can be reduced, the cost can be reduced, and the safety of the switching power supply circuit can be improved.

Description

A switching power supply circuit, semiconductor chip and power supply device

technical field

The present application relates to the field of power supply technology, and in particular, to a switching power supply circuit, a semiconductor chip and a power supply device.

Background technique

Switch Mode Power Supply (SMPS), referred to as switching power supply, also known as switching power supply, switching converter, is a power supply. The input of switching power supply is mostly AC power (such as mains) or DC power, and the output is mostly equipment that requires DC power, such as personal computer, and the function of switching power supply is to convert the voltage and current between the two.

At present, 12V5A switching power supplies generally use two Schott-level diodes and a heat sink to achieve their functions. However, the switching power supply designed with this circuit is usually inefficient, and the losses of the diodes in the circuit are relatively high. At the same time, due to the relatively large heat dissipation components, the labor cost is increased, and in the manual processing process, problems such as component damage, contact electrical corrosion, oxidation, etc. may be caused by mistakes, and even the contact resistance may increase, leaving various safety issues. hidden danger.

Utility model content

The embodiments of the present invention provide a switching power supply circuit, a semiconductor chip and a power supply device, aiming at improving the efficiency of the switching power supply, reducing the loss of diodes in the circuit, reducing the cost and improving the safety of the circuit.

In the first aspect, a switching power supply circuit provided by an embodiment of the present invention may include: an overcurrent protection circuit, an electromagnetic interference EMI filter circuit, an input rectification filter circuit, a main conversion circuit, a voltage feedback circuit, and a pulse width modulation PWM control circuit. and a secondary synchronous rectifier circuit; the main conversion circuit includes the first MOS transistor and a flyback transformer; the secondary synchronous rectifier circuit includes a second MOS transistor; wherein the input end of the overcurrent protection circuit is connected to the alternating current connected, the overcurrent protection circuit is used to power off the switching power supply circuit when the current input to the switching power supply circuit exceeds the rated current; the input end of the EMI filter circuit and the output end of the overcurrent protection circuit connected to filter out the interference signal of the switching power supply circuit; the input end of the input rectification filter circuit is connected to the output end of the EMI filter circuit for outputting the first DC voltage; the original source of the main conversion circuit The side is connected to the output end of the input rectifier and filter circuit, and is used for transmitting the first DC voltage to the secondary side of the main conversion circuit through the flyback transformer; the input of the secondary synchronous rectifier circuit The terminal is connected to the secondary side of the main conversion circuit, and is used for rectifying and filtering through the second MOS tube in the secondary synchronous rectification circuit to output a second DC voltage; the input terminal of the voltage feedback circuit is connected to The output end of the secondary synchronous rectification circuit is connected to feed back the second DC voltage to the PWM control circuit; the input end of the PWM control circuit is connected to the output end of the voltage feedback circuit, and is also connected to the PWM control circuit. The primary side of the main conversion circuit is connected to stabilize the second DC voltage by adjusting the duty ratio of the first MOS transistor in the main conversion circuit.

Compared with the switching power supply circuit in the prior art, in the switching power supply circuit provided by the embodiment of the present invention, in the flyback topology, the secondary selects a synchronous rectifier tube instead of a Schottky diode to complete the corresponding circuit function, thereby reducing the diode cost. losses and improve efficiency. The embodiment of the utility model avoids the use of larger heat sink components, reduces the production cost and the probability of subsequent failures, and improves the safety of the circuit.

In a possible implementation manner, the main conversion circuit further includes a resistor-capacitor diode RCD absorption circuit, the input rectification filter circuit includes a first capacitor and a second capacitor; the RCD absorption circuit is used to absorb the first capacitor. The peak voltage during the turn-off process of a MOS transistor and the reflected voltage of the secondary coil on the secondary side are discharged to the first capacitor and the second capacitor.

In a possible implementation manner, when the first MOS transistor is turned on, the flyback transformer stores energy to drive the second MOS transistor to turn off; when the first MOS transistor is turned off, the The flyback transformer releases the stored energy to the secondary side through coupling, and drives the second MOS transistor to conduct.

In a possible implementation manner, the EMI filter circuit includes a differential mode filter capacitor and a common mode filter inductor; the differential mode filter capacitor is connected across the neutral wire and the live wire to eliminate differential mode interference; the common mode filter The inductor is connected in series in the EMI filter circuit for suppressing the common mode interference of the alternating current and preventing the switching power supply circuit from interfering with the alternating current.

In a possible implementation manner, the input rectification filter circuit further includes a rectifier bridge;

The input rectification filter circuit is specifically configured to: perform full-wave rectification through the rectifier bridge, and output the first DC voltage through filtering by the first capacitor and the second capacitor.

In a possible implementation manner, the PWM control circuit includes a PWM control chip IC; the voltage feedback circuit is specifically configured to: feed back the second DC voltage to the feedback FB pin of the PWM control IC.

In a possible implementation manner, the PWM control circuit is specifically configured to adjust the duty cycle of the first MOS transistor by modulating the gate bias of the first MOS transistor according to the second DC voltage ratio, to achieve a stable voltage output of the switching power supply circuit.

In a possible implementation manner, the main conversion circuit further includes an auxiliary winding on the primary side; the auxiliary winding is connected to the PWM control circuit for supplying power to the PWM control IC.

In a second aspect, an embodiment of the present invention provides a semiconductor chip, and the semiconductor chip may include the switching power supply circuit described in the first aspect.

In a third aspect, an embodiment of the present invention further provides a power supply device, the device may include the switching power supply circuit described in the first aspect and its optional embodiments or the chip described in the second aspect, and the device can realize the first On the one hand, the switching power supply circuit described in its optional embodiments has the beneficial effects. The apparatus includes a memory and a processor, the memory is used for storing a computer program, the computer program may include program instructions, and the processor is used for controlling and managing the actions of the apparatus according to the program instructions. Optionally, the above-mentioned power supply apparatus may further include a transceiver, and the transceiver is used to support the communication between the apparatus and other communication devices.

Description of drawings

The accompanying drawings needed to be used in the embodiments of the present utility model will be introduced below.

1 is a schematic diagram of the working principle of a switching power supply circuit provided by an embodiment of the present invention;

FIG. 2 is a circuit schematic diagram of a switching power supply circuit provided by an embodiment of the present invention.

Detailed ways

The embodiment of the present utility model provides a switching power supply circuit, comprising: an overcurrent protection circuit, an electromagnetic interference EMI filter circuit, an input rectification filter circuit, a main conversion circuit, a voltage feedback circuit, a pulse width modulation PWM control circuit and a secondary synchronous rectification circuit The main conversion circuit includes the first MOS tube and the flyback transformer, and the secondary synchronous rectifier circuit includes the second MOS tube. Such a switching power supply circuit improves the efficiency of the switching power supply and reduces the diode in the circuit. loss.

The appearances of the terms "comprising" and "having" and any variations thereof in the description, claims and drawings of this solution are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but optionally also includes unlisted steps or units, or optionally also includes For other steps or units inherent to these processes, methods, products or devices. In addition, the terms "first", "second", "third", etc. are used to distinguish different objects and not to describe a specific order.

In order to make those skilled in the art better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described implementation The examples are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

A detailed description is given below with reference to the figures.

Please refer to FIG. 1. FIG. 1 is a schematic diagram of the working principle of a switching power supply circuit provided by an embodiment of the present invention. As can be seen from FIG. 1, the switching power supply circuit 100 includes: an overcurrent protection circuit 1001, an EMI filter circuit 1002, and an input rectification filter circuit. Circuit 1003 , main conversion circuit 1004 , voltage feedback circuit 1005 , PWM control circuit 1006 and secondary synchronous rectification circuit 1007 . As shown in FIG. 1 , the alternating current (ie, AC) is input to the switching power supply circuit 100, and after passing through the overcurrent protection circuit 1001, the EMI filter circuit 1002, the input rectifier filter circuit 1003, the flyback transformer and the secondary synchronous rectifier circuit 1007, it is output to the load The DC voltage that meets the requirements; wherein, the voltage feedback circuit 1005 obtains the DC voltage output to the load and feeds it back to the PWM control circuit 1006. The PWM control circuit 1006 adjusts the on-time of the first MOS according to the DC voltage to stabilize the voltage. The RCD absorption circuit is used to absorb leakage inductance energy, such as the superposition of the peak voltage and reflected voltage caused by the leakage inductance energy. Optionally, power is supplied to the PWM control IC in the PWM control circuit through the auxiliary winding of the flyback transformer. The embodiments of the present invention do not limit the specific connection manners between modules or circuits in the switching power supply circuit.

The structure and function of the switching power supply circuit 100 provided by the embodiment of the present invention will be described in detail below. Please refer to FIG. 2. FIG. 2 is a circuit schematic diagram of the switching power supply circuit provided by the embodiment of the present invention. The embodiment does not limit the specific circuit content in the case of implementing the same or similar circuit functions.

As shown in FIG. 2, the switching power supply circuit 100 may include: an overcurrent protection circuit 1001, an EMI filter circuit 1002, an input rectification filter circuit 1003, a main conversion circuit 1004, a voltage feedback circuit 1005, a PWM control circuit 1006, and a secondary synchronous rectification circuit Circuit 1007; the main conversion circuit 1004 includes the first MOS transistor and a flyback transformer; the secondary synchronous rectifier circuit 1007 includes a second MOS transistor; wherein, the input end of the overcurrent protection circuit 1001 is connected to the alternating current , the overcurrent protection circuit 1001 is used to power off the switching power supply circuit when the current input to the switching power supply circuit exceeds the rated current; the input end of the EMI filter circuit 1002 is connected to the overcurrent protection circuit 1001 The output end of the EMI filter circuit 1003 is connected to the output end of the EMI filter circuit 1002 for filtering out the interference signal of the switching power supply circuit; The primary side of the main conversion circuit 1004 is connected to the output end of the input rectification filter circuit 1003, and is used for transmitting the first DC voltage to the secondary side of the main conversion circuit 1004 through the flyback transformer; The input end of the secondary synchronous rectification circuit 1007 is connected to the secondary side of the main conversion circuit 1004 for rectifying and filtering through the second MOS transistor in the secondary synchronous rectification circuit 1007 to output a second DC voltage; the input end of the voltage feedback circuit 1005 is connected to the output end of the secondary synchronous rectification circuit 1007 for feeding back the second DC voltage to the PWM control circuit 1006 ; the input of the PWM control circuit 1006 The terminal is connected to the output terminal of the voltage feedback circuit 1005, and is also connected to the primary side of the main conversion circuit 1004, so as to adjust the duty cycle of the first MOS transistor in the main conversion circuit 1004 to Stabilize the second DC voltage.

Compared with the switching power supply circuit in the prior art, in the switching power supply circuit provided by the embodiment of the present invention, in the flyback topology, the secondary selects a synchronous rectifier tube instead of a Schottky diode to complete the corresponding circuit function, thereby reducing the diode cost. losses and improve efficiency. The embodiment of the utility model avoids the use of larger heat sink components, reduces the production cost and the probability of subsequent failures, and improves the safety of the circuit.

In a possible implementation manner, the main conversion circuit 1004 further includes a resistor-capacitor diode RCD absorption circuit, the input rectification filter circuit 1003 includes a first capacitor and a second capacitor; the RCD absorption circuit is used to absorb all the The peak voltage during the turn-off process of the first MOS transistor and the reflected voltage of the secondary coil on the secondary side are discharged to the first capacitor and the second capacitor. Wherein, the first capacitor and the second capacitor are bulk capacitors. Since the working process of the transformer (ie the flyback transformer) is to store energy first and then release it, instead of just transferring energy, the transformer is essentially a coupled inductor, and the coupled inductor is used to transfer energy, which can not only realize the input and output Isolation, but also realizes the transformation of the voltage, rather than just relying on the duty cycle to adjust the voltage. Since this coupled inductor (ie, the flyback transformer) is not an ideal device, there is leakage inductance, and stray inductance also exists in the actual line. When the MOS tube is turned off, the energy in the leakage inductance and stray inductance will generate a high voltage spike at the drain of the MOS, which will cause damage to the device. Therefore, the leakage inductance energy is processed by the RCD absorption circuit, C (ie capacitor) is used to temporarily store the leakage inductance energy, and R (ie resistance) is used to dissipate it.

In a possible implementation manner, when the first MOS transistor is turned on, the flyback transformer stores energy to drive the second MOS transistor to turn off; when the first MOS transistor is turned off, the The flyback transformer releases the stored energy to the secondary side through coupling, and drives the second MOS transistor to conduct. When the first MOS transistor is turned on, the primary current of the transformer increases linearly under the action of the input voltage. The primary voltage of the transformer is induced to the secondary, and the second MOS tube is reversely cut off. When the first MOS tube is turned off, the primary current of the transformer is forcibly turned off, then the primary inductance will generate an induced electromotive force on the primary side during the MOS turn-off process. According to the law of electromagnetic induction, the induced electromotive force is coupled to the secondary through the winding of the transformer. Since the same-named end of the secondary is opposite to the primary, the induced electromotive force of the secondary is positive on the top and negative on the bottom. When the induced electromotive force of the secondary reaches the output voltage, the second MOS transistor is turned on. The energy stored in the primary inductance when the MOS is turned on is coupled to the secondary inductance through the magnetic core, and then released into the secondary output capacitor through the secondary coil. In the process of transferring energy to the output capacitor, since the secondary output capacitor has a large capacity and the voltage is basically unchanged, the secondary voltage is clamped at the output voltage. When the first MOS is turned on again, the next cycle starts.

In a possible implementation manner, the EMI filter circuit 1002 includes a differential mode filter capacitor and a common mode filter inductor; the differential mode filter capacitor is connected across the neutral wire and the live wire to eliminate differential mode interference; the common mode filter capacitor is used to eliminate differential mode interference; A filter inductor is connected in series in the EMI filter circuit 1002 to suppress the common mode interference of the alternating current and prevent the switching power supply circuit 100 from interfering with the alternating current. The EMI filter circuit of the input part is mainly used to absorb the instantaneous high-voltage pulse interference signal to ensure the normal operation of the circuit.

In a possible implementation manner, the input rectification filter circuit 1003 further includes a rectifier bridge; the input rectifier filter circuit 1003 is specifically configured to perform full-wave rectification through the rectifier bridge, and through the first capacitor and the The filtering of the second capacitor outputs the first DC voltage. The input rectification filter circuit is composed of a BD rectifier bridge and a Bulk capacitor, and converts the input alternating current into direct current through full-wave rectification and filtering.

In a possible implementation manner, the PWM control circuit 1006 includes a PWM control chip IC; the voltage feedback circuit 1005 is specifically configured to: feed back the second DC voltage to the feedback FB lead of the PWM control IC. foot. The PWM control circuit is mainly used to adjust the conduction time of the MOS transistor according to the received feedback voltage, so as to achieve the function of adjusting or stabilizing the output voltage.

In a possible implementation manner, the PWM control circuit 1006 is specifically configured to change the conduction of the second MOS transistor by modulating the gate bias of the first MOS transistor according to the second DC voltage. On time, the duty ratio of the first MOS transistor can be adjusted, and the stable voltage output of the switching power supply circuit 100 can be realized.

In a possible implementation manner, the main conversion circuit 1004 further includes an auxiliary winding on the primary side; the auxiliary winding is connected to the PWM control circuit 1006 for supplying power to the PWM control IC. Power is supplied to the PWM control chip through the auxiliary winding on the primary side of the transformer (ie, the auxiliary winding in the primary coil) through the power supply pin connected to the PWM control chip.

It can be understood that the switching power supply circuit provided by the embodiment of the present invention can be applied to a chip with a driving function, and can also be applied to a device or an electronic product with a driving function; the switching power supply circuit provided by the embodiment of the present invention also It can be used in power adapters to provide terminal equipment such as personal notebook computers, desktop computers, and mobile phones with voltages that meet the requirements of the corresponding equipment. The embodiments of the present invention do not limit the application of this circuit.

In yet another embodiment of the present invention, a semiconductor chip is also provided, and the semiconductor chip may be a chip of the switching power supply circuit described in the first aspect, or may integrate the switching power supply circuit described in the first aspect and other external circuit chip.

The specific embodiments described above further describe the purposes, technical solutions and beneficial effects of the embodiments of the present invention in further detail. It should be understood that the above descriptions are only specific implementations of the embodiments of the present invention, and It is not intended to limit the protection scope of the embodiments of the present invention. Any modification, equivalent replacement, improvement, etc. made on the basis of the technical solutions of the embodiments of the present invention shall be included in the protection of the embodiments of the present invention. within the range.

In the several embodiments provided by the present invention, it should be understood that the disclosed method may be implemented in other manners. For example, the above-described embodiments are only illustrative, and the division of the circuits and modules is only a logical function division. In actual implementation, there may be other division methods, such as multiple units, circuits, modules or components. May be combined or may be integrated into another system, or some features may be omitted, or not implemented.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model, but not to limit them; although the present utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that : it can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements to some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the various embodiments of the present utility model Scope of technical solutions.

Claims (10)

1. A switching power supply circuit, comprising: the device comprises an overcurrent protection circuit, an electromagnetic interference (EMI) filter circuit, an input rectification filter circuit, a main conversion circuit, a voltage feedback circuit, a Pulse Width Modulation (PWM) control circuit and a secondary synchronous rectification circuit; the main conversion circuit comprises a first MOS tube and a flyback transformer; the secondary synchronous rectification circuit comprises a second MOS tube; wherein,

the input end of the over-current protection circuit is connected with alternating current, and the over-current protection circuit is used for powering off the switching power supply circuit when the current input into the switching power supply circuit exceeds rated current;

the input end of the EMI filter circuit is connected with the output end of the overcurrent protection circuit and is used for filtering interference signals of the switching power supply circuit;

the input end of the input rectifying filter circuit is connected with the output end of the EMI filter circuit and is used for outputting a first direct current voltage;

the primary side of the main conversion circuit is connected with the output end of the input rectification filter circuit and is used for transmitting the first direct current voltage to the secondary side of the main conversion circuit through the flyback transformer;

the input end of the secondary synchronous rectification circuit is connected with the secondary side of the main conversion circuit and used for performing rectification filtering through the second MOS tube in the secondary synchronous rectification circuit and outputting a second direct-current voltage;

the input end of the voltage feedback circuit is connected with the output end of the secondary synchronous rectification circuit and is used for feeding back the second direct-current voltage to the PWM control circuit;

the input end of the PWM control circuit is connected with the output end of the voltage feedback circuit, and is also connected with the primary side of the main conversion circuit, and the PWM control circuit is used for stabilizing the second direct current voltage by adjusting the duty ratio of the first MOS tube in the main conversion circuit.

2. The circuit of claim 1, wherein the main conversion circuit further comprises a resistor-capacitor diode (RCD) snubber circuit, and the input rectifying and filtering circuit comprises a first capacitor and a second capacitor;

the RCD absorption circuit is used for absorbing spike voltage in the turn-off process of the first MOS tube and reflected voltage of the secondary coil on the secondary side, and discharging the spike voltage and the reflected voltage to the first capacitor and the second capacitor.

3. The circuit of claim 2, wherein when the first MOS transistor is turned on, the flyback transformer stores energy to drive the second MOS transistor to turn off; when the first MOS tube is turned off, the flyback transformer releases the stored energy to the secondary side through coupling, and drives the second MOS tube to be conducted.

4. The circuit of claim 1, wherein the EMI filter circuit comprises a differential mode filter capacitor and a common mode filter inductor; the differential mode filter capacitor is in cross connection with a zero line and a live line and is used for eliminating differential mode interference; the common-mode filter inductor is connected in the EMI filter circuit in series and used for suppressing common-mode interference of the alternating current and preventing the switching power supply circuit from interfering with the alternating current.

5. The circuit of claim 2, wherein the input rectifying and filtering circuit further comprises a rectifying bridge;

the input rectifying and filtering circuit is specifically configured to: and full-wave rectification is carried out through the rectifier bridge, and the first direct-current voltage is output through filtering of the first capacitor and the second capacitor.

6. The circuit of claim 1, wherein the PWM control circuit comprises a PWM control chip IC; the voltage feedback circuit is specifically configured to: and feeding back the second direct current voltage to a feedback FB pin of the PWM control IC.

7. The circuit according to claim 6, wherein the PWM control circuit is specifically configured to adjust a duty ratio of the first MOS transistor by modulating a gate bias of the first MOS transistor according to the second direct-current voltage, so as to achieve stable voltage output of the switching power supply circuit.

8. The circuit of claim 6, wherein the primary conversion circuit further comprises an auxiliary winding on the primary side; and the auxiliary winding is connected with the PWM control circuit and used for supplying power to the PWM control IC.

9. A semiconductor chip comprising the switching power supply circuit according to any one of claims 1 to 8.

10. A power supply device comprising the switching power supply circuit according to any one of claims 1 to 8 or the semiconductor chip according to claim 9.

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