CN216086500U

CN216086500U - Feedback control chip and switching power supply system

Info

Publication number: CN216086500U
Application number: CN202121449202.6U
Authority: CN
Inventors: 王伟华; 姚超; 张允超; 张秀红
Original assignee: On Bright Electronics Shanghai Co Ltd
Current assignee: On Bright Electronics Shanghai Co Ltd
Priority date: 2021-06-28
Filing date: 2021-06-28
Publication date: 2022-03-18
Anticipated expiration: 2031-06-28
Also published as: TWM625404U

Abstract

The embodiment of the utility model provides a feedback control chip and a switching power supply system. According to the feedback control chip provided by the embodiment of the utility model, the feedback control chip is applied to a switching power supply system, comprises an output voltage pin and an optical coupler driving pin, and further comprises: and a first end of the constant voltage feedback loop control module is connected to the output voltage pin, and a second end of the constant voltage feedback loop control module is connected to the optocoupler driving pin, wherein the constant voltage feedback loop control module comprises a first compensation circuit. According to the scheme provided by the embodiment of the utility model, the constant voltage feedback loop control module is integrated in the feedback control chip, and the compensation circuit is integrated in the constant voltage feedback loop control module, so that the chip is integrated with a constant voltage control function, the number of pins of the chip is reduced, the number of peripheral compensation devices is reduced, the integration level of the system is improved, the components of the system are saved, and the miniaturization design of the system is facilitated.

Description

Feedback control chip and switching power supply system

Technical Field

The utility model belongs to the field of integrated circuits, and particularly relates to a feedback control chip and a switching power supply system.

Background

In recent years, as the screen of a mobile device such as a smartphone, a tablet computer, a notebook computer, or the like becomes larger, the processor speed becomes faster, resulting in that the power consumption of the device becomes large, and the capacity of a power supply battery is also increasing continuously to maintain the use time demand of a customer. The charging power of the corresponding device is also getting larger, however, in the conventional design, the physical limitation of the USB maximum current is limited, and the provision of larger charging power can only be realized by increasing the output voltage.

The USB association strives towards universal chargers, i.e. chargers that can charge devices with various power requirements, where the output power allows. Therefore, the output voltage and the output current need to be preset for several steps or need to be continuously adjustable to meet the requirements of various devices. In the prior art, the number of chip pins of a feedback control chip of an alternating current to direct current (ACDC) converter is large, and the number of peripheral compensation components is also large, so that the requirement for miniaturization of latest market products cannot be met.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides a feedback control chip and a switching power supply system, which can integrate a constant voltage feedback loop control module in the feedback control chip and integrate a compensation circuit in the constant voltage feedback loop control module, so that the chip is integrated with a constant voltage control function, the number of pins of the chip is reduced, the number of peripheral compensation devices is reduced, the integration level of the system is improved, system components are saved, and the miniaturization design of the system is facilitated.

In a first aspect, an embodiment of the present invention provides a feedback control chip, which is applied to a switching power supply system, where the feedback control chip includes an output voltage pin and an optocoupler drive pin, and further includes: and a first end of the constant voltage feedback loop control module is connected to the output voltage pin, and a second end of the constant voltage feedback loop control module is connected to the optocoupler driving pin, wherein the constant voltage feedback loop control module comprises a first compensation circuit.

In a second aspect, an embodiment of the present invention provides a feedback control chip, which is applied to a switching power supply system, and the feedback control chip further includes an optocoupler driving pin, an output current detection positive pin, and an output current detection negative pin, and further includes: and a first end of the constant current feedback loop control module is connected to the output current detection positive pin, a second end of the constant current feedback loop control module is connected to the output current detection negative pin, and a third end of the constant current feedback loop control module is connected to the optocoupler driving pin, wherein the constant current feedback loop control module comprises a third compensation circuit.

In a third aspect, an embodiment of the present invention provides a switching power supply system, which includes the optical coupler and the feedback control chip as described in the first aspect and the second aspect.

The feedback control chip and the switching power supply system of the embodiment of the utility model can integrate the constant voltage feedback loop control module in the feedback control chip and integrate the compensation circuit in the constant voltage feedback loop control module, so that the chip is integrated with a constant voltage control function, the pin number of the chip is reduced, the number of peripheral compensation devices is reduced, the integration level of the system is improved, the components of the system are saved, and the miniaturization design of the system is facilitated.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described below, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 shows a schematic structural diagram of a switching power supply system 100 provided in the prior art;

fig. 2 is a schematic structural diagram of a switching power supply system 200 according to an embodiment of the present invention;

FIG. 3 is a pin diagram of a feedback control chip according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram illustrating a feedback control chip capable of implementing constant voltage and constant current control according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a feedback control chip capable of implementing constant voltage control according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram illustrating a feedback control chip capable of implementing constant current control according to an embodiment of the present invention;

fig. 7 is a schematic structural diagram of a constant voltage/constant current feedback loop control module according to a first embodiment of the present invention;

fig. 8 is a circuit diagram of an output voltage discharging module according to another embodiment of the present invention;

fig. 9 is a schematic diagram illustrating a circuit structure of an output line drop compensation module according to another embodiment of the present invention;

fig. 10 is a schematic structural diagram of a constant voltage/constant current feedback loop control module according to a second embodiment of the present invention;

fig. 11 is a schematic structural diagram of a constant voltage feedback loop control module according to a first embodiment of the present invention;

fig. 12 is a schematic structural diagram of a constant voltage feedback loop control module according to a second embodiment of the present invention;

fig. 13 is a schematic structural diagram of a constant current feedback loop control module according to a first embodiment of the present invention; and

fig. 14 shows a schematic structural diagram of a constant current feedback loop control module according to a second embodiment of the present invention.

Detailed Description

Features and exemplary embodiments of various aspects of the present invention will be described in detail below, and in order to make objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the utility model and are not to be construed as limiting the utility model. It will be apparent to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

For better understanding of the present invention, a switching power supply system provided in the prior art is first described below, and referring to fig. 1, fig. 1 shows a schematic structural diagram of a switching power supply system 100 provided in the prior art. In the prior art, in order to meet the requirements of a new power supply with adjustable output voltage and current, such as USB Type-C, a switching power supply system (e.g., ACDC power supply) including a conventional feedback control chip is provided, as shown in fig. 1, the switching power supply system 100 mainly includes a rectifier bridge 110, a power converter 120, a driver chip 130, a feedback control chip 140, and the like, wherein the feedback control chip 140 includes at least 10 pins, if the chip is to be miniaturized, a relatively expensive package, such as SSOP10/QFN16, and the like, must be adopted, and peripheral compensation devices (e.g., capacitors C1-C4 and resistors R1-R2, and the like) are very many, which results in poor system reliability, higher cost, and is also not favorable for product miniaturization.

The pins comprise a current feedback pin IFB, a voltage feedback pin VFB, an optocoupler driving pin OPTO, an output current detection positive pin ISP, an output current detection negative pin ISN, a load switch driving pin GATE, a chip reference ground pin GND, an output voltage pin VO, a protocol communication port DP/CC1, a protocol communication port DN/CC2 and the like.

Therefore, in order to solve the problems in the prior art, embodiments of the present invention provide a novel switching power supply system. First, a switching power supply system according to an embodiment of the present invention will be described.

Referring to fig. 2, fig. 2 is a schematic structural diagram of a switching power supply system 200 according to an embodiment of the present invention. As shown in fig. 2, the switching power supply system 200 mainly includes a rectifier bridge 210, a power converter 220, a driver chip 230, a feedback control chip 240, and the like, wherein the feedback control chip 240 may include 8 pins, for example, an optocoupler drive pin OPTO, an output current detection positive pin ISP, an output current detection negative pin ISN, a load switch drive pin GATE, a chip ground reference pin GND, an output voltage pin VO, a protocol communication port DP/CC1, and a protocol communication port DN/CC2, which are less than the number of pins included in the feedback control chip 140 in the related art, for example, which is at least less than a voltage feedback pin VFB and a current feedback pin IFB, and the feedback control chip 240 is a highly integrated multi-level output voltage and output current adjustable feedback control chip, and the chip 240 integrates a feedback loop inside the chip, which may adopt an inexpensive package such as the most commonly used SOP8 and the like, meanwhile, the chip 240 integrates resistors, capacitors and the like for constant voltage, constant current or constant voltage and constant current loop compensation inside the chip, so that only one resistor to optical coupler is needed at the periphery of the chip, which can reduce the interference of system layout to the maximum extent, improve the integration level of the system, save components of the system and is beneficial to realizing the miniaturization design of the system.

As an example, the first terminal of the rectifier bridge 210 may be used to receive the voltage Vin, the second terminal may be connected to the first terminal of the power converter 220, the second terminal of the power converter 220 may be connected to the first terminal of the driving chip 230, the second terminal of the driving chip 230 may be connected to a reference ground via a capacitor Cfb, the first terminal of the capacitor Cfb may be connected to the first terminal of the optical coupler, the second terminal of the optical coupler may be connected to the reference ground, the third terminal of the optical coupler may be connected to the OPTO pin of the chip via a resistor Ropto, and the fourth terminal of the optical coupler may be connected to the reference ground, the third terminal of the power converter 220 may be connected to the first terminal of a capacitor Co, the second terminal of the capacitor Co may be connected to the fourth terminal of the power converter 220 and to the reference ground, and the first terminal of the capacitor Co may also be connected to the Vo pin of the chip and the first terminal of the load switch M2, the second terminal of the load switch M2 may be connected to the GATE pin of the chip, the third terminal of the load switch M2 may be connected to the second terminal of the capacitor Co via resistors Rcable, Ro and Rs, where the resistor Rs is a sampling resistor for sampling the output current, and its two terminals may be connected to the ISN and ISP pins of the chip, respectively.

In addition, since the feedback control chip 240 provided by the embodiment of the present invention integrates a complete feedback loop inside the chip, the chip may additionally add many loop-related functions. For example, the functions built in the feedback control chip 240 may be as follows: the circuit has the functions of output constant voltage control and loop feedback, output constant current control and loop feedback, output line voltage drop compensation, output voltage dynamic enhancement, maximum current clamping driven by an optical coupler, chip soft start, output voltage and current soft switching, discharge of an output capacitor during output voltage switching and the like. Meanwhile, the feedback control chip 240 may also be integrated with various secondary side output protections, such as Over Voltage Protection (OVP), Under Voltage Protection (UVP), Over Current Protection (OCP), and/or Optical Line Protection (OLP).

The feedback control chip provided by the embodiment of the present invention may be suitable for, for example, an off-line switching power supply system (off-line AC to DC), the main power topology may include, but is not limited to, a flyback converter, any suitable off-line switching power supply topology may employ the feedback control chip provided by the embodiment of the present invention, a structure of the switching power supply system is as shown in fig. 2, a pin of the feedback control chip is as shown in fig. 3, and fig. 3 illustrates a pin diagram of the feedback control chip provided by the embodiment of the present invention. It should be noted that the system and chips shown in fig. 2 and 3 are provided as examples only. The number of pins of the feedback control chip provided in the embodiment of the present invention is not limited to 8, and may be changed according to an actual system application, for example, the number of pins of the chip may be correspondingly expanded, for example, a plurality of General-Purpose Input/Output (GPIO) pins may be added to the pins of the chip shown in fig. 3.

As an example, the feedback control chip provided in the embodiment of the present invention mainly includes the following pins: a first pin (e.g., a detection and discharge pin (e.g., VO pin) of an output voltage of a system), a second pin (e.g., an output current sampling pin (e.g., ISN, ISP pin)), a third pin (e.g., a driving pin (e.g., OPTO pin) of an OPTO-coupler), a fourth pin (e.g., a driving pin (e.g., GATE pin) of a load switch), a fifth pin (e.g., a pin (e.g., DP/CC1 pin) of a fast charge/PD protocol communication), a sixth pin (e.g., a pin (e.g., DP/CC2 pin)) of a fast charge/PD protocol communication, and the like. The functions of the above-described pins are explained below with reference to fig. 2.

As an example, the ISP pin may be connected to a first terminal of the output current sampling resistor Rs for implementing constant current control and OCP control of the chip.

As an example, the ISN pin may be connected to the second terminal of the output current sampling resistor Rs for implementing the constant current control and OCP control of the chip.

As an example, the Vo pin may be connected to a first terminal (e.g., a positive electrode) of the output capacitor Co for implementing a constant voltage control of the chip and a discharge control of the output voltage switching process.

As an example, the OPTO pin may be connected to a first end of the resistor Ropto (e.g., an end of the resistor distal from the optocoupler) for enabling control of the system loop.

As an example, the GND pin may be connected to the second terminal (e.g., the negative electrode) of the output capacitor Co, and may also be connected to the negative voltage terminal of the load.

As one example, the GATE pin may be connected to the GATE of the load switch M2. It should be noted that in some embodiments, as shown in fig. 2, the load switch M2 is illustrated as an NMOS, and the load switch M2 is connected to the positive terminal of the output. However, in other embodiments, the load switch may be PMOS, and the load switch may be connected to the negative terminal of the output, which is not limited by the utility model. In still other embodiments, the output voltage Vo may be directly output to the load, in which case, there is no load switch in the system, and the GATE pin may be left floating, may be connected to the ground reference through a resistor, or may be directly connected to the ground reference according to the requirements of different switch types.

As an example, the DP/CC1 pin and the DN/CC2 pin may support the fast charging protocol or the PD protocol through internal switching, and may also support any other suitable communication protocol, which is not limited by the present invention. In addition, the number of the communication pins is not limited to two, and in practical application, the number of the communication pins can be increased to meet various communication protocol requirements of the system.

As an example, the feedback control chip provided in the embodiment of the present invention may include an output voltage pin and an optical coupler driving pin, and may further include a constant voltage feedback loop control module, where a first end of the constant voltage feedback loop control module may be connected to the output voltage pin, and a second end of the constant voltage feedback loop control module may be connected to the optical coupler driving pin, where the constant voltage feedback loop control module may include a compensation circuit, and is configured to enable the system to have a preset time domain performance and a preset frequency domain performance.

As another example, the feedback control chip provided in the embodiment of the present invention may include an optocoupler driving pin, an output current detection positive pin, and an output current detection negative pin, and may further include a constant current feedback loop control module, where a first end of the constant current feedback loop control module may be connected to the output current detection positive pin, a second end of the constant current feedback loop control module may be connected to the output current detection negative pin, and a third end of the constant current feedback loop control module may be connected to the optocoupler driving pin, where the constant current feedback loop control module may include a compensation circuit, and is configured to enable the system to have a preset time domain performance and a preset frequency domain performance.

As an example, the feedback control chip provided in the embodiment of the present invention may include an output voltage pin, an output current detection positive pin, an output current detection negative pin, and an optocoupler drive pin, and may further include a constant voltage/constant current feedback loop control module, where a first end of the constant voltage/constant current feedback loop control module may be connected to the output voltage pin, a second end of the constant voltage/constant current feedback loop control module may be connected to the output current detection positive pin, a third end of the constant voltage/constant current feedback loop control module may be connected to the output current detection negative pin, and a fourth end of the constant voltage/constant current feedback loop control module may be connected to the optocoupler drive pin, where the constant voltage/constant current feedback loop control module may include a compensation circuit for enabling a system to be in a preset time domain performance and a preset frequency domain performance.

Therefore, according to the scheme provided by the embodiment of the utility model, the constant voltage and/or constant current feedback loop control module is integrated in the feedback control chip, and the compensation circuit is integrated in the constant voltage and/or constant current feedback loop control module, so that the chip is integrated with a constant voltage and/or constant current control function, the number of pins of the chip is reduced, the number of peripheral compensation devices is reduced, the integration level of a system is improved, components of the system are saved, and the miniaturization design of the system is facilitated.

The feedback control chip 240 provided by the present invention is described in detail below with reference to a first embodiment, and specifically, with reference to fig. 4, fig. 4 shows a schematic structural diagram of the feedback control chip capable of implementing constant voltage and constant current control provided by the embodiment of the present invention.

As an example, as shown in fig. 4, the feedback control chip 240 may include, for example, the following modules: a protocol communication module 2401, an output voltage and current protection control module 2402, a Vo discharge control module 2403, a UVLO/LDO discharge module 2404, a digital/MCU control unit 2405, a constant voltage/constant current feedback loop control module 2406, a load switch drive module 2407, and the like.

Wherein, the first terminal of the protocol communication module 2401 may be connected to a DP/CC1 communication port, the second terminal may be connected to a DN/CC2 communication port, the third terminal may be connected to the first terminal of the micro control unit 2405, the first terminal of the output voltage and current protection control module 2402 may be connected to the second terminal of the micro control unit 2405, the first terminal of the Vo discharge control module 2403 may be connected to the third terminal of the micro control unit 2405, the first terminal of the UVLO/LDO discharge module 2404 may be connected to the Vo pin, the second terminal may be connected to the fourth terminal of the micro control unit 2405, the first terminal, the second terminal and the third terminal of the constant voltage/constant current feedback loop control module 2406 may be connected to the OPTO pin, the ISP pin and the ISN pin, respectively, the fourth terminal may be connected to the Vo pin, for receiving the output current of the system via the ISP pin and the ISN pin and receiving the output voltage of the system via the Vo pin, the fifth terminal may be connected to the fifth terminal of the micro control unit 2405, the first terminal of the load switch driving module 2407 may be connected to the GATE pin, and the second terminal may be connected to the sixth terminal of the micro control unit 2405.

It can be seen that the feedback control chip 240 includes a constant voltage/constant current feedback loop control module 2406, so that the above chip 240 can be applied in a switching power supply system for implementing constant voltage control and constant current control.

The feedback control chip provided by the present invention is described in detail below with reference to a second embodiment, and specifically, with reference to fig. 5, fig. 5 shows a schematic structural diagram of the feedback control chip capable of implementing constant voltage control provided by the embodiment of the present invention. As shown in fig. 5, the feedback control chip 340 may include, for example, the following modules: the control circuit comprises a protocol communication module 3401, an output voltage and current protection control module 3402, a Vo discharge control module 3403, a UVLO/LDO discharge module 3404, a digital/MCU control unit 3405, a constant voltage feedback loop control module 3406, a load switch driving module 3407 and the like.

Wherein, a first end of the protocol communication module 3401 may be connected to a DP/CC1 communication port, a second end may be connected to a DN/CC2 communication port, a third end may be connected to a first end of the micro control unit 3405, a first end of the output voltage and current protection control module 3402 may be connected to a second end of the micro control unit 3405, a first end of the Vo discharge control module 3403 may be connected to a third end of the micro control unit 3405, a first end of the UVLO/LDO discharge module 3404 may be connected to a Vo pin, a second end may be connected to a fourth end of the micro control unit 3405, a first end of the constant voltage feedback loop control module 3406 may be connected to an OPTO pin, a second end may be connected to the Vo pin for receiving an output voltage of the system via the Vo pin, the third end may be connected to a fifth end of the micro control unit 3405, a first end of the load switch driving module 3407 may be connected to a GATE pin, and the second terminal may be connected to a sixth terminal of the micro control unit 3405.

As can be seen, the feedback control chip 340 includes a constant voltage feedback loop control module 3406, so that the above chip 340 can be applied to a switching power supply system for implementing constant voltage control.

The feedback control chip provided by the present invention is described in detail below with reference to a third embodiment, and specifically, with reference to fig. 6, fig. 6 shows a schematic structural diagram of the feedback control chip capable of implementing constant current control provided by the embodiment of the present invention. As shown in fig. 6, the feedback control chip 440 may include, for example, the following modules: the control circuit comprises a protocol communication module 4401, an output voltage and current protection control module 4402, a Vo discharge control module 4403, a UVLO/LDO discharge module 4404, a digital/MCU control unit 4405, a constant current feedback loop control module 4406, a load switch driving module 4407 and the like.

Wherein, the first terminal of the protocol communication module 4401 may be connected to a DP/CC1 communication port, the second terminal may be connected to a DN/CC2 communication port, the third terminal may be connected to the first terminal of the micro control unit 4405, the first terminal of the output voltage and current protection control module 4402 may be connected to the second terminal of the micro control unit 4405, the first terminal of the Vo discharge control module 4403 may be connected to the third terminal of the micro control unit 4405, the first terminal of the UVLO/LDO discharge module 4404 may be connected to the Vo pin, the second terminal may be connected to the fourth terminal of the micro control unit 4405, the first terminal, the second terminal and the third terminal of the constant current feedback loop control module 4406 may be connected to an OPTO pin, an ISP pin and an ISN pin, respectively, for receiving the output current of the system via the ISP pin and the ISN pin, the fourth terminal may be connected to the fifth terminal of the micro control unit 2405, the first terminal of the load switch driving module 4407 may be connected to the GATE pin, and the second terminal may be connected to a sixth terminal of the micro control unit 4405.

It can be seen that the feedback control chip 440 includes the constant current feedback loop control module 4406, so that the above chip 440 can be applied to a switching power supply system for implementing constant current control.

The constant voltage/constant current feedback loop control module 2406 shown in fig. 4 is described in detail with reference to fig. 7, and specifically, fig. 7 shows a schematic structural diagram of the constant voltage/constant current feedback loop control module provided in the first embodiment of the present invention.

As shown in fig. 7, the constant voltage/constant current feedback loop control module 2406' may include a first branch between the OPTO pin and the VO pin, and a second branch between the ISN and ISP pins and the OPTO pin, wherein the first branch may be used to receive an output voltage of the system via the VO pin to implement constant voltage control, and the second branch may be used to receive an output current of the system via the ISN and ISP pins to implement constant current control.

In some embodiments, the first branch may include an output voltage sampling module 510, a constant voltage loop Transconductance error Amplifier (OTA)511, a compensation circuit 512 of the constant voltage loop, a driving capability enhancement buffer 513 of the constant voltage loop, a constant voltage loop voltage Amplifier 514, a constant voltage loop optical coupling driving isolation module 515 (e.g., a diode), and the like, and it should be noted that any suitable module having an isolation function is within the scope of the present invention, and the diode is exemplified below. In other embodiments, the first branch may further include an output voltage discharging module 516, an output line drop compensation module 517, and the like.

Wherein a first terminal of the output voltage sampling module 510 may be connected to the VO pin, a second terminal may be connected to a ground reference, a first terminal (e.g., a negative phase input terminal) of a constant voltage loop transconductance error amplifier (OTA)511 may be connected to a third terminal of the output voltage sampling module 510, a second terminal (e.g., a positive phase input terminal) may be used to receive a constant voltage reference voltage Vref _ cv, a first terminal of a compensation circuit 512 of the constant voltage loop may be connected to a third terminal (e.g., an output terminal) of the constant voltage loop transconductance error amplifier (OTA)511, a second terminal may be connected to a first terminal of a driving capability enhancement buffer 513 of the constant voltage loop, a first terminal of the constant voltage loop voltage amplifier 514 may be connected to a second terminal of the buffer 513, a second terminal may be connected to a first terminal (e.g., a positive pole) of a diode 515, a second terminal (e.g., a negative pole) of the diode 515 may be connected to the OPTO pin, and the output voltage discharging module 516 may be connected between the Vo pin and the reference ground, and both ends of the output line drop compensating module 517 may be connected to both ends of the resistor Rd.

The functions of the above modules are described in detail below by way of example, and as an example, referring to fig. 2 and 7, the output voltage sampling module 510 may be configured to sample the divided output voltage of the system, and reduce the output voltage to a reasonable voltage range for the subsequent stage adjustment module to use. For example, the output voltage sampling module 510 may include a voltage dividing module, such as a resistor R1 and a resistor Rd, which are connected in series between the VO pin and the ground reference, and the main functions of the output voltage sampling module 510 are to participate in a feedback loop of a subsequent constant voltage loop, dynamic boost compensation, and OVP/UVP protection.

Specifically, the dynamic enhancement compensation function is realized by the following way: the output voltage is detected, a reasonable output voltage range is set, once the output voltage is detected to exceed the preset output voltage range, the dynamic enhancing circuit is activated, and the output voltage is pulled back to the preset output voltage range by conducting current sinking/sinking on the output of the compensating circuit 512 of the rear-stage constant voltage loop.

As one example, a constant voltage loop transconductance error amplifier (OTA)511 may be used to compare the sampled output voltage with a constant voltage reference voltage Vref _ cv to produce an error current output. It should be noted that the constant voltage reference voltage Vref _ cv may be a fixed value, or may be a variable value configured by the MCU control unit (see fig. 4) or the like, which is not limited by the present invention. When starting or switching the output voltage, soft switching of starting soft start and output voltage step-up and step-down can be realized in a Vref _ cv soft rising and soft falling mode. To improve the dynamic performance of the system, the output voltage of the transconductance error amplifier (OTA)511 needs to be within a certain range (e.g., a range between Vgm _ min and Vgm _ max). When the output voltage sampling module 510 detects that the output voltage exceeds the dynamically enhanced threshold range, the output of the transconductance error amplifier (OTA)511 may be sunk to pull the output voltage back to the preset output voltage range.

As an example, the compensation circuit 512 of the constant voltage loop may be used to make the system at reasonable time-domain and frequency-domain performance. For example, the compensation circuit 512 may include a resistor R2 and a capacitor C1 connected between the output terminal of the transconductance error amplifier (OTA)511 and the reference ground, and a capacitor C2 connected between the output terminal of the transconductance error amplifier (OTA)511 and the reference ground, wherein the resistor R2 and the capacitor C1 are connected in series, and reasonable time domain performance and frequency domain performance can be obtained by setting reasonable resistance and capacitance values, and it should be noted that the present invention is not limited to the compensation circuit, and any other suitable circuit capable of implementing the compensation function is within the scope of the present invention. Specifically, the time domain performance may be determined according to the specification requirements of the user, while the frequency domain performance may be scan tested by a loop analyzer using methods such as small signal injection analysis, typically, the stable system open loop phase margin may need to be above, for example, 45 degrees, and the gain margin may need to be above, for example, 10-12 dB.

As one example, since the driving capability of some of the transconductance error amplifiers (OTAs) 511 may be very weak, the driving capability of the transconductance error amplifiers (OTAs) 511 may be enhanced by providing the driving capability enhancement buffer 513 of the constant voltage loop.

In some embodiments, since the output voltage range of some transconductance error amplifier (OTA)511 may not be able to fully satisfy the requirement of driving the external optical coupler, in this case, the output voltage range of the transconductance error amplifier (OTA)511 may be increased by the constant voltage loop voltage amplifier 514, so that a sufficient driving voltage range may be provided to fully satisfy the requirement of driving the external optical coupler, and simultaneously, the maximum value of the driving current may be clamped to the set value inside the chip. However, in other embodiments, the constant voltage loop voltage amplifier 514 is not required to increase the output voltage range, since some transconductance error amplifier (OTA)511 output voltage ranges are fully satisfactory for driving the external optocouplers.

As an example, in order to further provide chip performance, for example, in order to prevent the two loop systems from interfering with each other in different modes, the constant voltage loop and the constant current loop may be isolated by providing the constant voltage loop optical coupling driving isolation module 515 and the constant current loop optical coupling driving isolation module 523.

In some embodiments, in order to further improve the performance of the constant voltage loop, an output voltage discharging module 516 may be further provided, and the output voltage discharging module 516 may be configured to turn on when the output voltage is switched by the constant voltage reference voltage Vref _ cv under the light and empty load condition. As a dummy load of the system, when the output voltage decreases, the output voltage discharging module 516 may be configured to rapidly discharge the output voltage to a set voltage range, so as to meet the system voltage-decreasing time and performance specification. The output voltage discharging module 516 may be configured to suppress overshoot of the output voltage when the output voltage is boosted, so that the output voltage returns to the set voltage range as soon as possible.

It should be noted that in the embodiment shown in fig. 7, the output voltage discharging module 516 realizes the discharging function by means of a constant current source. However, in other embodiments, for example, referring to fig. 8, fig. 8 shows a circuit structure diagram of an output voltage discharging module according to another embodiment of the present invention, wherein the output voltage discharging module 516 implements the discharging function by way of a resistor (e.g., Rdis), and any other suitable circuit with the discharging function is within the scope of the present invention.

In some embodiments, in order to further improve the performance of the constant voltage loop, since the output wire may cause the line end voltage to drop, it may be necessary to compensate the line voltage drop by providing the output line voltage drop compensation module 517, for example, by multiplying the output voltage (including information related to the output current) of the output current sampling and amplifying module 518 by a suitable scaling parameter k, providing a compensation current for the output wire by using a Voltage Controlled Current Source (VCCS) or the like, making the compensation current flow into the sampling point of the output voltage sampling module 510, i.e., the common end of the resistor R1 and the resistor Rd, and by selecting a suitable scaling reference k, the compensation for the line end voltage drop caused by the output wire may be implemented, so that the line voltage is always maintained at the set value in the full load range.

However, in other embodiments, referring to fig. 9, fig. 9 shows a schematic circuit diagram of an output line drop compensation module according to another embodiment of the present invention, and as can be seen from fig. 9, it compensates a drop in the line terminal voltage caused by an output line by superimposing a voltage source proportional to the output current on an input terminal (e.g., a negative phase input terminal) of a transconductance error amplifier (OTA)511, that is, superimposing a voltage proportional to the output current on a constant voltage reference voltage Vref _ cv, so that the line voltage is always maintained at a set value in a full load range.

In some embodiments, the second branch may include an output current sampling and amplifying module 518, a constant current loop transconductance error amplifier (OTA)519, a compensation circuit 520 of the constant current loop, a driving capability enhancement buffer 521 of the constant current loop, a constant current loop voltage amplifier 522, a constant current loop optical coupling driving isolation module 523 (e.g., a diode), and the like, and it should be noted that any suitable module having an isolation function is within the scope of the present invention, and a diode is exemplified below.

Wherein a first terminal (e.g., a negative phase input terminal) of the output current sampling and amplifying module 518 may be connected to the ISN pin, a second terminal (e.g., a positive phase input terminal) may be connected to the ISP pin, a first terminal (e.g., a negative phase input terminal) of the constant current loop transconductance error amplifier (OTA)519 may be connected to a third terminal (e.g., an output terminal) of the output current sampling and amplifying module 518, the second terminal (e.g., the positive phase input terminal) may be configured to receive the constant current reference voltage Vref _ cc, a first terminal of the compensation circuit 520 of the constant current loop may be connected to a third terminal (e.g., an output terminal) of the transconductance error amplifier (OTA)519, a second terminal may be connected to a first terminal of the drive capability enhancement buffer 521 of the constant current loop, a first terminal of the constant current loop voltage amplifier 522 may be connected to a second terminal of the buffer 521, the second terminal may be connected to a first terminal (e.g., positive), a second terminal (e.g., a cathode) of diode 523 may be connected to the OPTO pin.

The functions of the above modules are described in detail by way of example, and referring to fig. 2 and 7, as an example, the output current sampling and amplifying module 518 may be configured to sample a voltage across a sampling resistor Rs (see fig. 2), wherein the current across the sampling resistor Rs is the output current, and amplify the sampled voltage to an appropriate voltage range for use by a subsequent stage through a voltage amplifying module therein. The main function of the output current sampling and amplifying module 518 is to participate in the post-stage constant current loop feedback loop and OCP protection.

As one example, a constant current loop transconductance error amplifier (OTA)519 may be used to compare the output voltage from the output current sampling and amplification module 518 with a constant current reference voltage Vref _ cc to produce an error current output. It should be noted that the constant current reference voltage Vref _ cc may be a fixed value, or may be a variable value configured by the MCU control unit (see fig. 4) or the like, which is not limited by the present invention. When the output current is switched, the soft switching of the current magnitude can be realized by means of Vref _ cc soft rising or soft falling.

As an example, the compensation circuit 520 of the constant current loop may be used to make the system at reasonable time domain performance and frequency domain performance. For example, the compensation circuit 520 may include a resistor R20 and a capacitor C10 connected between the output terminal of the transconductance error amplifier (OTA)519 and the reference ground, and a capacitor C20 connected between the output terminal of the transconductance error amplifier (OTA)519 and the reference ground, wherein the resistor R20 and the capacitor C10 are connected in series, and reasonable time-domain performance and frequency-domain performance can be obtained by setting reasonable resistance and capacitance values, and it should be noted that the present invention is not limited to the compensation circuit, and any other suitable circuit capable of implementing the compensation function is within the scope of the present invention. Specifically, the time domain performance may be determined according to the specification requirements of the user, while the frequency domain performance may be scan tested by a loop analyzer using methods such as small signal injection analysis, typically, the stable system open loop phase margin may need to be above, for example, 45 degrees, and the gain margin may need to be above, for example, 10-12 dB.

As one example, since the driving capability of some of the transconductance error amplifier (OTA)519 may be very weak, the driving capability of the transconductance error amplifier (OTA)519 may be enhanced by providing a driving capability enhancement buffer 521 of the constant current loop.

As an example, since the output voltage range of some transconductance error amplifier (OTA)519 may not be able to fully satisfy the requirement of driving the external optical coupler, in this case, the output voltage range of the transconductance error amplifier (OTA)519 may be increased by the constant current loop voltage amplifier 522, so that a sufficient driving voltage range may be provided to fully satisfy the requirement of driving the external optical coupler, and simultaneously, the maximum value of the driving current may be clamped to a set value inside the chip. However, in other embodiments, the constant current loop voltage amplifier 522 is not required to increase the output voltage range, since some transconductance error amplifier (OTA)519 has an output voltage range that fully satisfies the requirements for driving the external optocoupler.

It should be noted that the constant voltage/constant current feedback loop control module 2406 shown in fig. 7 is provided only as an example, and other implementations of the constant voltage/constant current feedback loop control module may also exist, for example, referring to fig. 10, fig. 10 shows a schematic structural diagram of the constant voltage/constant current feedback loop control module provided in the second embodiment of the present invention.

As shown in fig. 10, the constant voltage/constant current feedback loop control module 2406 ″ is similar to the constant voltage/constant current feedback loop control module 2406 ' shown in fig. 7, wherein the same components are labeled with the same reference numerals, and the difference between the two is mainly that the constant voltage/constant current feedback loop control module 2406 ″ reduces the constant voltage loop voltage amplifier 514 and the constant current loop voltage amplifier 522 on the basis of the constant voltage/constant current feedback loop control module 2406 ', and two input terminals of the transconductance error amplifier (OTA)511 ' and the transconductance error amplifier (OTA)519 ' are interchanged, for example, a negative phase input terminal of the transconductance error amplifier (OTA)511 shown in fig. 7 may be connected to the third terminal of the output voltage sampling module 510, a positive phase input terminal thereof may be used for receiving the constant voltage reference voltage Vref _ cv, and a positive phase input terminal of the transconductance error amplifier (OTA)511 ' shown in fig. 10 may be connected to the third terminal of the output voltage sampling module 510 A negative phase input terminal of which may be used to receive a constant voltage reference voltage Vref _ cv; and the negative phase input of the transconductance error amplifier (OTA)519 shown in fig. 7 may be connected to a third terminal (e.g., output terminal) of the output current sampling and amplifying module 518, and the positive phase input thereof may be used to receive the constant current reference voltage Vref _ cc, while the positive phase input of the transconductance error amplifier (OTA) 519' shown in fig. 10 may be connected to the third terminal (e.g., output terminal) of the output current sampling and amplifying module 518, and the negative phase input thereof may be used to receive the constant current reference voltage Vref _ cc, i.e., the constant voltage/constant current feedback loop control module 2406 ″ may be applied in a scenario where the output voltage range of the transconductance error amplifier (OTA) can fully satisfy the requirement of driving the external opto-coupler.

It should be noted, however, that the embodiment illustrated in FIG. 10 should be construed in a limiting sense and is not intended to limit the present invention. For example, in the first embodiment, the constant voltage/constant current feedback loop control module may reduce the output voltage discharge module 516 and/or the output line drop compensation module 517 on the basis of the constant voltage/constant current feedback loop control module 2406 ″ shown in fig. 10. In the second embodiment, the constant voltage loop voltage amplifier 514 between the constant voltage loop optical coupling driving isolation module 515 and the constant voltage loop driving capability enhancing buffer 513 may be added to the constant voltage/constant current feedback loop control module 2406 ″ shown in fig. 10 or the constant voltage/constant current feedback loop control module provided in the first embodiment, and in this case, two input terminals of the transconductance error amplifier (OTA) 511' shown in fig. 10 need to be interchanged, that is, the two input terminals need to be in the same state as the transconductance error amplifier (OTA)511 shown in fig. 7. In the third embodiment, the constant current loop voltage amplifier 522 between the constant current loop optical coupling driving isolation module 523 and the driving capability enhancement buffer 521 of the constant current loop may be added on the basis of the constant voltage/constant current feedback loop control module 2406 ″ shown in fig. 10 or the constant voltage/constant current feedback loop control module provided in the first embodiment, and in this case, two input terminals of the transconductance error amplifier (OTA) 519' shown in fig. 10 need to be interchanged, that is, two input terminals thereof need to be in the same state as the transconductance error amplifier (OTA)519 shown in fig. 7.

For simplicity of description, the corresponding functions of the components in fig. 10 are similar to the functions of the corresponding components in fig. 7, and since the functions of the components have been described in detail in fig. 7, the detailed description is omitted here.

The constant voltage feedback loop control module 3406 shown in fig. 5 is described in detail with reference to fig. 11, and specifically, fig. 11 shows a schematic structural diagram of the constant voltage feedback loop control module according to the first embodiment of the present invention.

As shown in fig. 11, the constant voltage feedback loop control module 3406 'is similar to the first branch shown in fig. 7, wherein the same components are denoted by the same reference numerals, and the constant voltage feedback loop control module 3406' may include an output voltage sampling module 510, a constant voltage loop transconductance error amplifier (OTA)511, a compensation circuit 512 of the constant voltage loop, a driving capability enhancement buffer 513 of the constant voltage loop, a constant voltage loop voltage amplifier 514, and the like. In other embodiments, the constant voltage feedback loop control module 3406' may further include an output voltage discharge module 516, an output line drop compensation module 517, and the like. Except that the isolation diode 515 may not be provided at this time.

For simplicity of description, the corresponding functions of the components in fig. 11 are similar to the functions of the corresponding components in fig. 7, and since the functions of the components have been described in detail in fig. 7, the detailed description is omitted here.

It should be noted that the constant voltage feedback loop control module 3406' shown in fig. 11 is provided merely as an example, and there may be other implementations of the constant voltage feedback loop control module, for example, referring to fig. 12, fig. 12 shows a schematic structural diagram of the constant voltage feedback loop control module provided in the second embodiment of the present invention.

As shown in fig. 12, the constant voltage feedback loop control module 3406 "is similar to the constant voltage feedback loop control module 3406' shown in fig. 11, wherein the same components are provided with the same reference numerals, the difference between the two is mainly that the constant voltage feedback loop control module 3406 ″ reduces the output voltage discharging module 516, the output line drop compensation module 517 and the constant voltage loop voltage amplifier 514 on the basis of the constant voltage feedback loop control module 3406', and the two input terminals of the transconductance error amplifier (OTA)511 are interchanged, that is, the positive phase input terminal of the transconductance error amplifier (OTA)511 may be connected to the output terminal of the output voltage sampling module 510, the negative phase input terminal may be configured to receive the reference voltage Vref _ cv, and the constant voltage feedback loop control module 3406 ″ may be applied in a scenario where the output voltage range of the transconductance error amplifier (OTA) can completely meet the requirement of driving the external optocoupler.

For simplicity of description, the corresponding functions of the components in fig. 12 are similar to the functions of the corresponding components in fig. 7, and since the functions of the respective components have been described in detail in fig. 7, the detailed description is omitted here.

The constant current feedback loop control module 4406 shown in fig. 6 is described in detail below with reference to fig. 13, and specifically, fig. 13 illustrates a schematic structural diagram of the constant current feedback loop control module according to the first embodiment of the present invention.

As shown in fig. 13, the constant current feedback loop control module 4406 'is similar to the second branch shown in fig. 7, wherein the same components are denoted by the same reference numerals, and the constant current feedback loop control module 4406' may include an output current sampling and amplifying module 518, a constant current loop transconductance error amplifier (OTA)519, a compensation circuit 520 of the constant current loop, a driving capability enhancement buffer 521 of the constant current loop, a constant current loop voltage amplifier 522, and the like. The difference is that the isolation diode 523 may not be provided at this time.

For simplicity of description, the corresponding functions of the components in fig. 13 are similar to the functions of the corresponding components in fig. 7, and since the functions of the components have been described in detail in fig. 7, the detailed description is omitted here.

It should be noted that the constant current feedback loop control module 4406' shown in fig. 13 is provided merely as an example, and other implementations of the constant current feedback loop control module may also exist, for example, referring to fig. 14, fig. 14 shows a schematic structural diagram of the constant current feedback loop control module provided in the second embodiment of the present invention.

As shown in fig. 14, the constant current feedback loop control module 4406 ″ is similar to the constant current feedback loop control module 4406 'shown in fig. 13, wherein the same components are denoted by the same reference numerals, and the difference between the two components is mainly that the constant current feedback loop control module 4406 ″ reduces the constant current loop voltage amplifier 522 on the basis of the constant current feedback loop control module 4406', and two input ends of a transconductance error amplifier (OTA)519 are interchanged, that is, a positive phase input end of the transconductance error amplifier (OTA)519 can be connected to an output end of the output current sampling and amplifying module 518, a negative phase input end can be used for receiving a reference voltage Vref _ cc, and the constant current feedback loop control module 4406 ″ can be applied in a scenario that an output voltage range of the transconductance error amplifier (OTA) can completely meet a requirement of driving an external optical coupler.

For simplicity of description, the corresponding functions of the components in fig. 14 are similar to the functions of the corresponding components in fig. 7, and since the functions of the respective components have been described in detail in fig. 7, the detailed description is omitted here.

In summary, the present invention provides a feedback control chip and a control method thereof, which can be applied to, for example, an offline switching power supply system, the feedback control chip can amplify an error between an output voltage or current and a constant voltage reference voltage or current through a transconductance error amplifier (OTA), and increase the driving capability of the transconductance error amplifier (OTA) by using a buffer (buffer), and optionally, can then adjust the voltage by using an operational amplifier to drive an optocoupler diode and transmit a feedback signal to a primary side PWM chip.

Through the technical scheme, the control loop can be integrated in the chip, and the chip is integrated with the following functions: the high-integration characteristic of the chip can meet the application of multiple output voltages such as PD/QC and the like.

It is to be understood that the utility model is not limited to the specific arrangements and instrumentality described above and shown in the drawings. A detailed description of known methods is omitted herein for the sake of brevity. In the above embodiments, several specific steps are described and shown as examples. However, the method processes of the present invention are not limited to the specific steps described and illustrated, and those skilled in the art can make various changes, modifications and additions or change the order between the steps after comprehending the spirit of the present invention.

The functional blocks shown in the above-described structural block diagrams may be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, it may be, for example, an electronic circuit, an Application Specific Integrated Circuit (ASIC), suitable firmware, plug-in, function card, or the like. When implemented in software, the elements of the utility model are the programs or code segments used to perform the required tasks. The program or code segments may be stored in a machine-readable medium or transmitted by a data signal carried in a carrier wave over a transmission medium or a communication link. A "machine-readable medium" may include any medium that can store or transfer information. Examples of a machine-readable medium include electronic circuits, semiconductor memory devices, ROM, flash memory, Erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, Radio Frequency (RF) links, and so forth. The code segments may be downloaded via computer networks such as the internet, intranet, etc.

It should also be noted that the exemplary embodiments mentioned in this patent describe some methods or systems based on a series of steps or devices. However, the present invention is not limited to the order of the above-described steps, that is, the steps may be performed in the order mentioned in the embodiments, may be performed in an order different from the order in the embodiments, or may be performed simultaneously.

As described above, only the specific embodiments of the present invention are provided, and it can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the system, the module and the unit described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again. It should be understood that the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive various equivalent modifications or substitutions within the technical scope of the present invention, and these modifications or substitutions should be covered within the scope of the present invention.

Claims

1. The utility model provides a feedback control chip, is applied to switching power supply system, its characterized in that, feedback control chip includes output voltage pin and opto-coupler drive pin to still include:

a constant voltage feedback loop control module having a first end connected to the output voltage pin and a second end connected to the optocoupler drive pin,

the constant voltage feedback loop control module comprises a first compensation circuit.

2. The feedback control chip of claim 1, further comprising an output current detection positive pin and an output current detection negative pin, and further comprising:

a constant current feedback loop control module, a first end of which is connected to the output current detection positive pin, a second end of which is connected to the output current detection negative pin, and a third end of which is connected to the optocoupler driving pin, wherein,

the constant current feedback loop control module comprises a second compensation circuit.

3. The feedback control chip of claim 1, wherein the constant voltage feedback loop control module further comprises:

the first end of the output voltage sampling module is connected to the output voltage pin, and the second end of the output voltage sampling module is connected to the reference ground;

a first transconductance error amplifier, a first end of which is connected to the third end of the output voltage sampling module, and a second end of which is used for receiving a first reference voltage; and

and a first end of the first buffer is connected to a third end of the first transconductance error amplifier through the first compensation circuit, and a second end of the first buffer is connected to the optocoupler driving pin.

4. The feedback control chip of claim 1, wherein the constant voltage feedback loop control module further comprises:

a first transconductance error amplifier, a first end of which is connected to the third end of the output voltage sampling module, and a second end of which is used for receiving a first reference voltage;

a first buffer having a first terminal connected to a third terminal of the first transconductance error amplifier via the first compensation circuit; and

and a first end of the first voltage amplifier is connected to a second end of the first buffer, and a second end of the first voltage amplifier is connected to the optical coupler driving pin.

5. The feedback control chip according to claim 3 or 4, wherein the constant voltage feedback loop control module further comprises:

and a discharge module, a first end of which is connected to the output voltage pin and a second end of which is connected to a reference ground, wherein the discharge module comprises a constant current source or a resistor.

6. The feedback control chip according to claim 3 or 4, wherein the constant voltage feedback loop control module further comprises:

and the first end of the output line voltage drop compensation module is connected to the third end of the output voltage sampling module, and the second end of the output line voltage drop compensation module is connected to the reference ground, or the first end of the output line voltage drop compensation module is connected to the second end of the first transconductance error amplifier, and the second end of the output line voltage drop compensation module is connected to the reference ground through a voltage source providing the first reference voltage.

7. The feedback control chip of claim 2, further comprising a first isolation module and a second isolation module, wherein,

the second end of the constant-voltage feedback loop control module is connected to the optocoupler driving pin through the first isolation module, and the third end of the constant-current feedback loop control module is connected to the optocoupler driving pin through the second isolation module.

8. The feedback control chip of claim 7, wherein the constant current feedback loop control module further comprises:

the first end of the output current sampling module is connected to the output current detection positive pin, and the second end of the output current sampling module is connected to the output current detection negative pin;

a first end of the second transconductance error amplifier is connected to the third end of the output current sampling module, and a second end of the second transconductance error amplifier is used for receiving a second reference voltage; and

and a first end of the second buffer is connected to a third end of the second transconductance error amplifier through the second compensation circuit, and a second end of the second buffer is connected to the optocoupler driving pin through the second isolation module.

9. The feedback control chip of claim 7, wherein the constant current feedback loop control module further comprises:

a first end of the second transconductance error amplifier is connected to the third end of the output current sampling module, and a second end of the second transconductance error amplifier is used for receiving a second reference voltage;

a second buffer, a first end of which is connected to a third end of the second transconductance error amplifier via the second compensation circuit; and

and a first end of the second voltage amplifier is connected to a second end of the second buffer, and a second end of the second voltage amplifier is connected to the optocoupler driving pin through the second isolation module.

10. The utility model provides a feedback control chip, is applied to switching power supply system, its characterized in that, feedback control chip still includes opto-coupler drive pin, output current detection positive pin and output current detection negative pin to still include:

the constant current feedback loop control module comprises a third compensation circuit.

11. The feedback control chip of claim 10, wherein the constant current feedback loop control module further comprises:

a first end of the third transconductance error amplifier is connected to the third end of the output current sampling module, and a second end of the third transconductance error amplifier is used for receiving a third reference voltage; and

and a first end of the third buffer is connected to a third end of the third transconductance error amplifier through the third compensation circuit, and a second end of the third buffer is connected to the optocoupler driving pin.

12. The feedback control chip of claim 10, wherein the constant current feedback loop control module further comprises:

a first end of the third transconductance error amplifier is connected to the third end of the output current sampling module, and a second end of the third transconductance error amplifier is used for receiving a third reference voltage;

a third buffer having a first terminal connected to a third terminal of the third transconductance error amplifier via the third compensation circuit; and

and a first end of the third voltage amplifier is connected to a second end of the third buffer, and a second end of the third voltage amplifier is connected to the optocoupler driving pin.

13. A switching power supply system comprising an optocoupler and a feedback control chip according to any of claims 1 to 12.