CN114567165A - Switch control circuit, switch control method thereof and switch power supply - Google Patents

Switch control circuit, switch control method thereof and switch power supply Download PDF

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Publication number
CN114567165A
CN114567165A CN202210171520.3A CN202210171520A CN114567165A CN 114567165 A CN114567165 A CN 114567165A CN 202210171520 A CN202210171520 A CN 202210171520A CN 114567165 A CN114567165 A CN 114567165A
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China
Prior art keywords
signal
coupled
circuit
feedback signal
switch control
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CN202210171520.3A
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Chinese (zh)
Inventor
曾强
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Shenzhen Biyi Microelectronics Co ltd
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Shenzhen Biyi Microelectronics Co ltd
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Priority to CN202210171520.3A priority Critical patent/CN114567165A/en
Publication of CN114567165A publication Critical patent/CN114567165A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention provides a switch control circuit, a switch control method thereof and a switch power supply. The switch control circuit is used for controlling a main switch tube in the switch power supply and comprises a feedback signal processing circuit, a signal conversion circuit and a driving signal generating circuit. The feedback signal processing circuit receives a feedback signal representing the output signal of the switching power supply, and the feedback signal processing circuit is used for generating a low-voltage side signal according to the feedback signal. The signal conversion circuit is coupled with the feedback signal processing circuit and is used for generating a high-voltage side signal according to the low-voltage side signal; the high side signal is an analog signal. The input end of the driving signal generating circuit is coupled to the second end of the signal conversion circuit, and the driving signal generating circuit is used for generating a switch control signal according to the high-voltage side signal. According to the switch control circuit, the switch control method and the switch power supply provided by the invention, high-precision constant voltage control and/or constant current control can be realized by directly sampling output.

Description

Switch control circuit, switch control method thereof and switch power supply
Technical Field
The invention belongs to the field of power electronics, relates to a switch control technology, and particularly relates to a switch control circuit, a switch control method thereof and a switch power supply.
Background
Switching power supplies are a major class of electronic power supplies, and are widely used in most electronic devices such as consumer electronics and communication devices due to their various advantages such as light weight, miniaturization, wide input voltage range, high power density/conversion efficiency, and low standby power consumption.
The buck switching power supply is a topology circuit commonly used in the switching power supply, and can be divided into a high-voltage side buck switching power supply and a low-voltage side buck switching power supply according to the arrangement position of a main switching tube in the switching power supply. The high-voltage side voltage reduction type switching power supply comprises a main switching tube, an inductor, an output capacitor and a diode. The first end of the main switch tube is coupled with the bus voltage, the first end of the inductor is coupled with the second end of the main switch tube, the first end of the output capacitor is coupled with the second end of the inductor, and the second end of the output capacitor is coupled with the input ground. The anode of the diode is coupled to the second end of the output capacitor, and the cathode of the diode is coupled to the first end of the inductor. In order to realize the constant current control of the buck switching power supply, a sampling resistor is generally disposed between the diode and the inductor to detect the current flowing through the inductor. However, the constant current control precision of the prior art scheme is not high, and in some application scenarios, higher requirements are provided for the precision of the output voltage and/or the output current of the switching power supply.
In view of the above, there is a need to provide a new structure or control method for solving at least some of the above problems.
Disclosure of Invention
The invention provides a switch control circuit, a switch control method thereof and a switch power supply, aiming at one or more problems in the prior art.
According to an aspect of the present invention, a switching control circuit is disclosed, for controlling a main switching tube in a switching power supply, the switching power supply being a high-side step-down type switching power supply, the switching control circuit comprising:
the input end of the feedback signal processing circuit receives a feedback signal representing the output signal of the switching power supply and is used for generating a low-voltage side signal according to the feedback signal; the feedback signal is a signal with reference to the ground as the input ground;
the first end of the signal conversion circuit is coupled with the output end of the feedback signal processing circuit and is used for generating a high-voltage side signal according to the low-voltage side signal; the high-voltage side signal is an analog signal; and
and the input end of the driving signal generating circuit is coupled with the second end of the signal conversion circuit, and the output end of the driving signal generating circuit is coupled with the main switching tube and used for generating a switching control signal according to the high-voltage side signal so as to control the main switching tube.
In one embodiment, the feedback signal processing circuit generates a low-voltage side signal from the feedback signal, the low-voltage side signal being a current signal.
In one embodiment, the feedback signal processing circuit comprises: and the input end of the pulse width generating circuit is coupled with the feedback signal end to receive the feedback signal and is used for generating a pulse width signal according to the feedback signal, and the duty ratio of the pulse width signal is proportional to the feedback signal.
In one embodiment, the feedback signal processing circuit includes: the first transconductance operational amplifier circuit has a first input terminal coupled to the feedback signal terminal for receiving the feedback signal, a second input terminal coupled to the first reference signal terminal for receiving the first reference signal, and an output terminal for outputting the low-voltage-side signal.
In one embodiment, the signal conversion circuit includes:
a source electrode of the field effect transistor is coupled with the feedback signal processing circuit, and a control end of the field effect transistor is coupled with a first voltage; and
the input end of the compensation signal generating circuit is coupled with the drain electrode of the field effect transistor, the output end of the compensation signal generating circuit outputs a compensation signal and is used for generating the compensation signal according to a first current, the high-voltage side signal is the compensation signal, and the first current is the current flowing through the drain electrode of the field effect transistor.
In one embodiment, the compensation signal generation circuit includes:
a current mirror, the first end of which is coupled with the drain electrode of the field effect transistor, and the second end of which outputs a current adjusting signal;
a first end of the third resistor is coupled with the second end of the current mirror, and a second end of the third resistor is coupled with the ground; and
the first end of the error amplifying circuit is coupled with the second end of the current mirror, the second end of the error amplifying circuit is coupled with the second reference signal end to obtain a second reference signal, and the output end of the error amplifying circuit outputs a compensation signal.
In one embodiment, the compensation signal generation circuit includes:
a current mirror, the first end of which is coupled with the drain electrode of the field effect transistor;
a first end of the third resistor is coupled with the second end of the current mirror;
a fourth resistor; the first end of the current mirror is coupled with the second end of the current mirror; and
the first end of the second capacitor is coupled to the second end of the fourth resistor, the second end of the second capacitor is coupled to the second end of the third resistor, and the first end of the second capacitor outputs the compensation signal.
In one embodiment, the compensation signal generation circuit includes:
a current mirror, the first end of which is coupled with the drain electrode of the field effect transistor, and the second end of which outputs a compensation signal; and
the first end of the third resistor is coupled to the second end of the current mirror, and the second end of the third resistor is coupled to ground.
In one embodiment, the compensation signal generation circuit includes:
a fifth resistor having a first end coupled to the second voltage and a second end coupled to the drain of the fet;
a first transconductance operational amplifier circuit, a first input terminal of which is coupled to the first end of the fifth resistor, and a second input terminal of which is coupled to the second end of the fifth resistor;
a first end of the second capacitor is coupled with the output end of the first transconductance operational amplification circuit, and a second end of the second capacitor is coupled with the ground;
a first input end of the second transconductance operational amplifier circuit is coupled to the first end of the second capacitor, and a second end of the second transconductance operational amplifier circuit is coupled to the third reference signal end to obtain a third reference signal; and
a first end of the third capacitor is coupled to the output end of the second transconductance operational amplifier circuit, a second end of the third capacitor is coupled to the ground, and a first end of the third capacitor outputs the compensation signal.
In one embodiment, the field effect transistor is an N-type junction field effect transistor or an N-type metal oxide semiconductor field effect transistor.
According to another aspect of the present invention, a switching power supply is disclosed, the switching power supply being a high-side buck switching power supply, the switching power supply comprising a switching control circuit as described in any one of the above.
According to still another aspect of the present invention, there is disclosed a switching control method for controlling a switching control circuit, the switching control method including:
receiving a feedback signal representing an output signal of the switching power supply, and generating a low-voltage side signal according to the feedback signal; the feedback signal is a signal with reference to the ground as the input ground;
generating a high-voltage side signal according to the low-voltage side signal; the high-voltage side signal is an analog signal; and
and generating a switch control signal according to the high-voltage side signal to control the main switching tube.
The invention provides a switch control circuit, a switch control method thereof and a switch power supply. The switch control circuit is used for controlling a main switch tube in the switch power supply, the switch power supply is a high-voltage side voltage reduction type switch power supply, and the switch control circuit comprises a feedback signal processing circuit, a signal conversion circuit and a driving signal generating circuit. The input end of the feedback signal processing circuit receives a feedback signal representing an output signal of the switching power supply, and the feedback signal processing circuit is used for generating a low-voltage side signal according to the feedback signal; the feedback signal is a signal whose reference ground is the input ground. The first end of the signal conversion circuit is coupled with the output end of the feedback signal processing circuit, and the signal conversion circuit is used for generating a high-voltage side signal according to the low-voltage side signal; the high side signal is an analog signal. The input end of the driving signal generating circuit is coupled with the second end of the signal conversion circuit, the output end of the driving signal generating circuit is used for being coupled with the main switching tube, and the driving signal generating circuit is used for generating a switch control signal according to the high-voltage side signal so as to control the main switching tube. According to the switch control circuit, the switch control method and the switch power supply provided by the invention, the output signal is directly sampled, so that high-precision constant voltage control and/or constant current control can be realized. In addition, the system working frequency of the switching power supply is not limited by the response speed of the signal conversion circuit, so that the high-frequency work of the system can be realized, the power density of the system is improved, and the volume of the system is reduced.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. In the drawings:
fig. 1 shows a schematic circuit diagram of a switching power supply according to an embodiment of the invention;
fig. 2 is a schematic circuit diagram of a signal conversion circuit according to an embodiment of the present invention;
fig. 3 shows a circuit configuration diagram of a signal conversion circuit according to another embodiment of the present invention;
FIG. 4 is a circuit diagram of a switch control circuit according to an embodiment of the invention;
fig. 5 is a circuit configuration diagram showing a switch control circuit according to another embodiment of the present invention;
fig. 6 shows a circuit configuration schematic of a switch control circuit according to a further embodiment of the invention;
fig. 7 is a circuit diagram of a switch control circuit according to an embodiment of the present invention.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
The description in this section is for several exemplary embodiments only, and the present invention is not limited only to the scope of the embodiments described. Combinations of different embodiments, and substitutions of features from different embodiments, or similar prior art means may be substituted for or substituted for features of the embodiments shown and described.
The term "coupled" or "connected" in this specification includes both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as a conductor, wherein the electrically conductive medium may contain parasitic inductance or parasitic capacitance, or through an intermediate circuit or component as described in the embodiments in the specification; indirect connections may also include connections through other active or passive devices that perform the same or similar function, such as connections through switches, signal amplification circuits, follower circuits, and so on. "plurality" or "plurality" means two or more. In addition, in the present invention, terms such as first and second are mainly used for distinguishing one technical feature from another technical feature, and do not necessarily require or imply any actual relationship or order between the technical features.
As shown in fig. 1, an embodiment of the present invention discloses a switching power supply, which is a high-side voltage-reducing switching power supply. The switching power supply comprises a main switching tube Q1, an inductor L1, a first capacitor C1 and a first diode D1. A first terminal of the main switch Q1 is coupled to the bus voltage, a first terminal of the inductor L1 is coupled to the second terminal of the main switch Q1, a first terminal of the first capacitor C1 is coupled to the second terminal of the inductor L1, an anode of the first diode D1 is coupled to the second terminal of the first capacitor C1, and a cathode of the first diode D1 is coupled to the second terminal of the main switch Q1. The switch control circuit 10 is used for controlling a main switch tube in the switch power supply. The switch control circuit 10 includes a feedback signal processing circuit 110, a signal conversion circuit 120, and a drive signal generation circuit 130. In one embodiment, the switch control circuit 10 includes a main switching transistor Q1. In another embodiment, the main switching tube Q1 is disposed outside the switch control circuit 10. As shown in fig. 1, an input terminal of the feedback signal processing circuit 110 receives a feedback signal representing an output signal of the switching power supply 10, and the feedback signal processing circuit is configured to generate a low-voltage side signal according to the feedback signal. The output signal of the switching power supply may be an output voltage and/or an output current of the switching power supply. The feedback signal is a signal whose reference ground is the input ground. The feedback signal processing circuit 110 generates a low-voltage side signal with reference to ground as an input ground according to the feedback signal. In one embodiment as shown in fig. 1, the switching power supply further includes a first resistor R1 and a second resistor R2, a first end of the second resistor R2 is coupled to a first end of the first capacitor C1, a first end of the first resistor R1 is coupled to a second end of the second resistor R2, and a second end of the first resistor R1 is coupled to the input ground. In addition, a first terminal of the first resistor R1 is coupled to a feedback signal terminal of the switch control circuit 10 to provide a feedback signal. A first terminal of the signal conversion circuit 120 is coupled to the output terminal of the feedback signal processing circuit 110, and the signal conversion circuit 120 is configured to generate a high-voltage side signal according to the low-voltage side signal, where the low-voltage side signal is an analog signal and the high-voltage side signal is also an analog signal. The high-voltage side signal is a signal based on the floating ground, and a switch control signal can be generated according to the high-voltage side signal to control the state of the main switch tube. The input terminal of the driving signal generating circuit 130 is coupled to the second terminal of the signal converting circuit 120, the output terminal of the driving signal generating circuit 130 is coupled to the main switch Q1, and the driving signal generating circuit 130 is configured to generate a switch control signal according to the high-side signal to control the main switch. Based on the switch control circuit, high-precision constant voltage control and/or constant current control can be realized by directly sampling output. In addition, the signal conversion circuit does not directly transmit the on-off signal of the main switching tube, the system working frequency of the switching power supply is not limited by the response speed of the signal conversion circuit, the high-frequency work of the system can be realized, the power density of the system is improved, and the volume of the system is reduced.
In another embodiment, the switching power supply includes a main switch Q1, an inductor L1, a first capacitor C1, a first diode D1, and a sampling resistor. A first terminal of the main switch Q1 is coupled to the bus voltage, a first terminal of the inductor L1 is coupled to the second terminal of the main switch Q1, a first terminal of the first capacitor C1 is coupled to the second terminal of the inductor L1, a first terminal of the sampling resistor is coupled to the second terminal of the first capacitor C1, an anode of the first diode D1 is coupled to the second terminal of the sampling resistor, and a cathode of the first diode D1 is coupled to the second terminal of the main switch Q1. The feedback signal end of the switch control circuit is coupled with the first end of the sampling resistor to obtain a feedback signal representing the output current of the switch power supply, so that the constant current control of the switch power supply is realized. The sampling resistor is connected in series on the output loop, so that the full integration of the output current is realized, and the constant current control precision is higher.
In an embodiment of the invention, the feedback signal represents an output voltage of the switching power supply, and the switching control circuit controls the output voltage of the switching power supply according to the feedback signal, so that constant voltage output can be realized. In another embodiment, the feedback signal represents the output current of the switching power supply, and the switching control circuit controls the output current of the switching power supply according to the feedback signal, so that constant current output can be realized. In a further embodiment, the feedback signal is indicative of an output voltage and an output current of the switching power supply, the output voltage and the output current of the switching power supply can be respectively characterized by time-sharing sampling, and the switching control circuit controls the output voltage and the output current of the switching power supply according to the feedback signal. In the invention, the output signal is directly sampled to carry out real-time feedback, so that excellent output dynamic response can be realized.
In an embodiment of the invention, the feedback signal processing circuit includes a first transconductance operational amplifier circuit, a first input terminal of the first transconductance operational amplifier circuit is coupled to the feedback signal terminal for receiving the feedback signal, a second input terminal of the first transconductance operational amplifier circuit is coupled to the first reference signal terminal for receiving the first reference signal, and an output terminal of the first transconductance operational amplifier circuit outputs the low-voltage side signal. The signal conversion circuit comprises a field effect transistor and a compensation signal generation circuit, wherein the source electrode of the field effect transistor is coupled with the output end of the feedback signal processing circuit, and the control end of the field effect transistor is coupled with the first voltage. The input end of the compensation signal generating circuit is coupled with the drain electrode of the field effect transistor, the output end of the compensation signal generating circuit outputs a compensation signal, the compensation signal generating circuit is used for generating a compensation signal according to a first current, the high-voltage side signal is the compensation signal, and the first current is the current flowing through the drain electrode of the field effect transistor. In one embodiment as shown in fig. 2, the signal conversion circuit 121 includes an N-type junction field effect transistor and a compensation signal generating circuit. The source electrode of the N-type junction field effect transistor is coupled with the feedback signal processing circuit, and the control end of the N-type junction field effect transistor is coupled with the ground. The N-type junction field effect transistor can be integrated through a general high-voltage process, a special process is not needed, and the chip cost is reduced. The compensation signal generating circuit comprises a current mirror and a third resistor R3, wherein the first end of the current mirror is coupled to the drain of the N-type junction field effect transistor, the second end of the current mirror is coupled to the first end of the third resistor R3, the second end of the third resistor R3 is coupled to the ground, and the second end of the current mirror outputs a compensation signal COMPH. The compensation signal generating circuit further comprises a second capacitor, wherein the first end of the second capacitor is coupled to the first end of the third resistor, and the second end of the second capacitor is coupled to the second end of the third resistor. The switch control circuit generates a switch control signal according to the compensation signal COMPH to control the switch state of the main switch tube. In a specific embodiment, the driving signal generating circuit includes a comparator, a first terminal of the comparator is coupled to the second terminal of the current mirror to obtain the compensation signal comp, a second terminal of the comparator is coupled to the sawtooth wave generating circuit, and an output terminal of the comparator is coupled to the control terminal of the main switching transistor Q1.
In another embodiment of the present invention, as shown in fig. 3, the signal converting circuit 122 includes an N-type metal oxide semiconductor field effect transistor (NMOS transistor for short) and a compensation signal generating circuit, a drain of the NMOS transistor is coupled to the compensation signal generating circuit, a source of the NMOS transistor is coupled to the feedback signal processing circuit, and a control terminal of the NMOS transistor is coupled to the first voltage Vb.
In an embodiment of the present invention, as shown in fig. 4, the switch control circuit includes a feedback signal processing circuit 113, a signal conversion circuit 123, and a driving signal generating circuit (not shown). The feedback signal processing circuit 113 includes a transconductance conversion circuit, an input end of which is coupled to the feedback signal, and the transconductance conversion circuit is configured to convert the feedback signal as a voltage signal into a low-voltage side signal as a current signal. The signal conversion circuit comprises a high-voltage type N-type junction field effect transistor and a compensation signal generation circuit, and converts a low-voltage side signal into a high-voltage side signal. The compensation signal generating circuit comprises a current mirror, a third resistor R3 and an error amplifying circuit, wherein the first end of the current mirror is coupled with the drain electrode of the N-type junction field effect transistor, and the current mirror outputs a current adjusting signal FBH according to the high-voltage side signal. The first terminal of the third resistor R3 is coupled to the second terminal of the current mirror, and the second terminal of the third resistor R3 is coupled to ground. The first end of the error amplifying circuit is coupled to the second end of the current mirror, the second end of the error amplifying circuit is coupled to the second reference signal end to obtain a second reference signal Vref2, and the output end of the error amplifying circuit outputs a compensation signal comp. The switch control circuit generates a switch control signal according to the compensation signal COMP to control the switch state of the switch tube. The low-voltage side signal and the compensation signal are not common ground signals, the low-voltage side signal is a signal with the reference ground being the ground, and the compensation signal is a signal with the reference ground being the floating ground, so that the low-voltage side signal cannot be directly used for controlling the switching action of the main switching tube, and the high-voltage side circuit can timely acquire a feedback signal through the signal conversion of the switching control circuit, thereby carrying out corresponding output control.
In another embodiment of the present invention, as shown in fig. 5, the switch control circuit includes a feedback signal processing circuit 114, a signal conversion circuit 124, and a driving signal generating circuit (not shown in the figure). The signal conversion circuit comprises a field effect transistor Q4 and a compensation signal generating circuit, and particularly, the field effect transistor Q4 is a high-voltage type NMOS transistor.
In an embodiment of the present invention, as shown in fig. 6, the switch control circuit includes a feedback signal processing circuit 115, a signal conversion circuit 125, and a driving signal generating circuit (not shown). The feedback signal processing circuit 115 includes a first transconductance operational amplifier circuit and a pulse width generation circuit. The first input end of the first transconductance operational amplifier circuit is coupled to the feedback signal end to receive the feedback signal, the second input end of the first transconductance operational amplifier circuit is coupled to the first reference signal end to receive the first reference signal Vref1, and the output end of the first transconductance operational amplifier circuit outputs a low-voltage side signal COMPL. The input end of the pulse width generating circuit is coupled with the output end of the first transconductance operational amplification circuit, the pulse width generating circuit is used for generating a pulse width signal according to the feedback signal, and the duty ratio of the pulse width signal is proportional to the feedback signal. The signal conversion circuit comprises a field effect transistor Q4 and a compensation signal generating circuit, wherein the drain of the field effect transistor is coupled to the input terminal of the compensation signal generating circuit, and the source of the field effect transistor is coupled to the output terminal of the feedback signal processing circuit 115. The compensation signal generating circuit comprises a current mirror, a third resistor R3, a fourth resistor R4 and a second capacitor C2. The first terminal of the current mirror is coupled to the drain of the fet Q4, the first terminal of the third resistor R3 is coupled to the second terminal of the current mirror, the second terminal of the third resistor R3 is coupled to the floating ground, and the first terminal of the fourth resistor R4 is coupled to the second terminal of the current mirror. A first end of the second capacitor C2 is coupled to the second end of the fourth resistor R4, a second end of the second capacitor C2 is coupled to the second end of the third resistor R3, and a first end of the second capacitor C2 outputs the compensation signal comp h. The switch control circuit converts a feedback signal at the low voltage side into a pulse width signal, the duty ratio of which is proportional to the feedback signal. The driving signal generating circuit obtains a high-voltage side signal through the processing of the signal conversion circuit, the high-voltage side signal is proportional to the duty ratio of the pulse width signal, and the switching state of the main switching tube can be controlled according to the feedback signal.
In another embodiment of the present invention, as shown in fig. 7, the switch control circuit includes a feedback signal processing circuit 116, a signal conversion circuit 126, and a driving signal generating circuit (not shown in the figure). The signal conversion circuit 126 includes a field effect transistor Q4 and a compensation signal generation circuit. The compensation signal generating circuit comprises a fifth resistor R5, a first transconductance operational amplifying circuit, a second capacitor C2, a second transconductance operational amplifying circuit and a third capacitor C3. The first terminal of the fifth resistor R5 is coupled to the second voltage, and the second terminal of the fifth resistor R5 is coupled to the drain of the fet. The first input terminal of the first transconductance operational amplifier circuit is coupled to the first terminal of the fifth resistor R5, and the second input terminal of the first transconductance operational amplifier circuit is coupled to the second terminal of the fifth resistor R5. The first terminal of the second capacitor C2 is coupled to the output terminal of the first transconductance operational amplifier circuit, the second terminal of the second capacitor C2 is coupled to the floating ground, and the first terminal of the second capacitor C2 outputs a voltage signal FBH. The first input terminal of the second transconductance operational amplifier circuit is coupled to the first terminal of the second capacitor C2, and the second terminal of the second transconductance operational amplifier circuit is coupled to the third reference signal terminal to obtain a third reference signal Vref 3. A first terminal of the third capacitor C3 is coupled to the output terminal of the second transconductance operational amplifier circuit, a second terminal of the third capacitor C3 is coupled to the floating ground, and a first terminal of the third capacitor C3 outputs the compensation signal comp h.
As can be seen from fig. 2, the driving signal generating circuit is a high-voltage side circuit, that is, the reference ground of the driving signal generating circuit is a floating ground, and the driving signal generating circuit obtains the compensation signal comp h through the signal converting circuit, and the specific operating principle is as follows: when the output voltage Vout of the switching power supply decreases, the low-voltage side signal COMPL increases, and the absolute value of the compensation signal COMPH increases. The driving signal generating circuit controls the conduction time or the working frequency of the main switching tube to increase (or both the conduction time and the working frequency are increased) according to the compensation signal COMPH, the transmission energy of the switching power supply is increased, and the output voltage is increased. On the contrary, when the output voltage Vout of the switching power supply increases, the low-voltage side signal COMPL increases, the absolute value of the compensation signal COMPH increases, the high-voltage side control circuit controls the conduction time or the working frequency of the main switching tube to decrease (or both the conduction time and the working frequency decrease) according to the compensation signal COMPH, the transmission energy of the switching power supply decreases, and the output voltage of the switching power supply decreases; and finally, the output voltage of the switching power supply is controlled at a set value. Similarly, according to the similar principle, the output current of the switching power supply can be controlled at the set value.
An embodiment of the present invention further discloses a switching power supply, which is a high-side voltage-reduction type switching power supply, and includes the switching control circuit as described in any one of the above.
An embodiment of the present invention further discloses a switch control method, where the switch control method is used to control a switch control circuit, and the switch control method includes: receiving a feedback signal representing an output signal of the switching power supply, and generating a low-voltage side signal according to the feedback signal; the feedback signal is a signal with reference to the ground as the input ground; generating a high-voltage side signal according to the low-voltage side signal; the high-voltage side signal is an analog signal; and generating a switch control signal according to the high-voltage side signal to control the main switching tube. In an embodiment, the switch control method is used for controlling the switch control circuit as described in any one of the above.
In another embodiment of the present invention, a switch control method includes: the input end of the feedback signal processing circuit receives a feedback signal representing the output signal of the switching power supply, the feedback signal processing circuit generates a low-voltage side signal according to the feedback signal, and the feedback signal is a signal with reference ground as input ground. The signal conversion circuit generates a high-voltage side signal according to the low-voltage side signal, and the high-voltage side signal is an analog signal. The driving signal generating circuit generates a switch control signal according to the high-voltage side signal to control the main switching tube.
In an embodiment of the invention, the low-side signal is a current signal. In another embodiment, the step of generating the low-voltage side signal according to the feedback signal specifically includes: and generating a pulse width signal according to the feedback signal, wherein the duty ratio of the pulse width signal is proportional to the feedback signal, and the pulse width signal is a low-voltage side signal.
Those skilled in the art should understand that the logic controls such as "high" and "low", "set" and "reset", "and gate" and "or gate", "non-inverting input" and "inverting input" in the logic controls referred to in the specification or the drawings may be exchanged or changed, and the subsequent logic controls may be adjusted to achieve the same functions or purposes as the above-mentioned embodiments.
The description and applications of the invention herein are illustrative and are not intended to limit the scope of the invention to the embodiments described above. The descriptions related to the effects or advantages in the specification may not be reflected in practical experimental examples due to uncertainty of specific condition parameters or influence of other factors, and the descriptions related to the effects or advantages are not used for limiting the scope of the invention. Variations and modifications of the embodiments disclosed herein are possible, and alternative and equivalent various components of the embodiments will be apparent to those skilled in the art. It will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, and with other components, materials, and parts, without departing from the spirit or essential characteristics thereof. Other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.

Claims (12)

1. A switch control circuit for controlling a main switch tube in a switch power supply, wherein the switch power supply is a high-side voltage-reducing switch power supply, the switch control circuit comprises:
the input end of the feedback signal processing circuit receives a feedback signal representing the output signal of the switching power supply and is used for generating a low-voltage side signal according to the feedback signal; the feedback signal is a signal with reference to the ground as the input ground;
the first end of the signal conversion circuit is coupled with the output end of the feedback signal processing circuit and is used for generating a high-voltage side signal according to the low-voltage side signal; the high-voltage side signal is an analog signal; and
and the input end of the driving signal generating circuit is coupled with the second end of the signal conversion circuit, and the output end of the driving signal generating circuit is coupled with the main switching tube and used for generating a switching control signal according to the high-voltage side signal so as to control the main switching tube.
2. The switch control circuit of claim 1, wherein the feedback signal processing circuit generates a low side signal from the feedback signal, the low side signal being a current signal.
3. The switch control circuit of claim 1, wherein the feedback signal processing circuit comprises:
and the input end of the pulse width generating circuit is coupled with the feedback signal end to receive the feedback signal and is used for generating a pulse width signal according to the feedback signal, and the duty ratio of the pulse width signal is proportional to the feedback signal.
4. The switch control circuit of claim 2, wherein the feedback signal processing circuit comprises:
the first transconductance operational amplifier circuit has a first input terminal coupled to the feedback signal terminal for receiving the feedback signal, a second input terminal coupled to the first reference signal terminal for receiving the first reference signal, and an output terminal for outputting the low-voltage-side signal.
5. The switch control circuit of claim 1, wherein the signal conversion circuit comprises:
a source electrode of the field effect transistor is coupled with the feedback signal processing circuit, and a control end of the field effect transistor is coupled with a first voltage; and
the input end of the compensation signal generating circuit is coupled with the drain electrode of the field effect transistor, the output end of the compensation signal generating circuit outputs a compensation signal and is used for generating the compensation signal according to a first current, the high-voltage side signal is the compensation signal, and the first current is the current flowing through the drain electrode of the field effect transistor.
6. The switch control circuit of claim 5, wherein the compensation signal generation circuit comprises:
a current mirror, the first end of which is coupled with the drain electrode of the field effect transistor, and the second end of which outputs a current adjusting signal;
a first end of the third resistor is coupled with the second end of the current mirror, and a second end of the third resistor is coupled with the ground; and
the first end of the error amplifying circuit is coupled with the second end of the current mirror, the second end of the error amplifying circuit is coupled with the second reference signal end to obtain a second reference signal, and the output end of the error amplifying circuit outputs a compensation signal.
7. The switch control circuit of claim 5, wherein the compensation signal generation circuit comprises:
a current mirror, the first end of which is coupled with the drain electrode of the field effect transistor;
a first end of the third resistor is coupled with the second end of the current mirror;
a fourth resistor; the first end of the current mirror is coupled with the second end of the current mirror; and
the first end of the second capacitor is coupled to the second end of the fourth resistor, the second end of the second capacitor is coupled to the second end of the third resistor, and the first end of the second capacitor outputs the compensation signal.
8. The switch control circuit of claim 5, wherein the compensation signal generation circuit comprises:
a current mirror, wherein the first end of the current mirror is coupled with the drain electrode of the field effect transistor, and the second end of the current mirror outputs a compensation signal; and
the first end of the third resistor is coupled to the second end of the current mirror, and the second end of the third resistor is coupled to ground.
9. The switch control circuit of claim 5, wherein the compensation signal generation circuit comprises:
a fifth resistor, a first end of which is coupled to the second voltage and a second end of which is coupled to the drain of the fet;
a first transconductance operational amplifier circuit, a first input terminal of which is coupled to the first end of the fifth resistor, and a second input terminal of which is coupled to the second end of the fifth resistor;
a first end of the second capacitor is coupled with the output end of the first transconductance operational amplification circuit, and a second end of the second capacitor is coupled with the ground;
a first input end of the second transconductance operational amplifier circuit is coupled to the first end of the second capacitor, and a second end of the second transconductance operational amplifier circuit is coupled to the third reference signal end to obtain a third reference signal; and
a first end of the third capacitor is coupled to the output end of the second transconductance operational amplifier circuit, a second end of the third capacitor is coupled to the ground, and a first end of the third capacitor outputs the compensation signal.
10. The switch control circuit of claim 5, wherein the field effect transistor is an N-type junction field effect transistor or an N-type metal oxide semiconductor field effect transistor.
11. A switching power supply, characterized in that it is a high side buck switching power supply comprising a switching control circuit according to any one of claims 1 to 10.
12. A switching control method for controlling a switching control circuit, the switching control method comprising:
receiving a feedback signal representing an output signal of the switching power supply, and generating a low-voltage side signal according to the feedback signal; the feedback signal is a signal with reference to the ground as the input ground;
generating a high-voltage side signal according to the low-voltage side signal; the high-voltage side signal is an analog signal; and
and generating a switch control signal according to the high-voltage side signal to control the main switching tube.
CN202210171520.3A 2022-02-24 2022-02-24 Switch control circuit, switch control method thereof and switch power supply Pending CN114567165A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210171520.3A CN114567165A (en) 2022-02-24 2022-02-24 Switch control circuit, switch control method thereof and switch power supply

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210171520.3A CN114567165A (en) 2022-02-24 2022-02-24 Switch control circuit, switch control method thereof and switch power supply

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CN114567165A true CN114567165A (en) 2022-05-31

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