TWM625404U - Feedback control chip and switching power supply system - Google Patents

Abstract

This creative embodiment provides a feedback control chip and a switching power supply system. According to the feedback control chip provided by the embodiment of the present invention, the feedback control chip is applied to a switching power supply system, the feedback control chip includes an output voltage pin and an optocoupler driving pin, and further includes: a constant voltage feedback loop control module, which The first end is connected to the output voltage pin, and the second end is connected to the optocoupler driving pin, wherein the constant voltage feedback loop control module includes a first compensation circuit. The above solution provided by this creative embodiment integrates the constant voltage feedback loop control module inside the feedback control chip, and integrates the compensation circuit inside the constant voltage feedback loop control module, so that the chip integrates the constant voltage control function At the same time, the number of pins of the chip is reduced, and the number of peripheral compensation devices is reduced, the integration of the system is improved, the system components are saved, and the miniaturized design of the system is realized.

Description

Feedback control chip and switching power supply system

This creation belongs to the field of integrated circuits, and in particular relates to a feedback control chip and a switching power supply system.

In recent years, as the screens of mobile devices such as smartphones, tablet computers, and notebook computers have become larger and processors have become faster, the power consumption of the devices has become large, and the capacity of the power supply batteries has continued to increase. Maintain customer usage time requirements. The charging power of the corresponding device also increases. However, in the traditional design, limited by the physical limitation of the maximum current of the Universal Serial Bus (USB), it can only be achieved by increasing the output voltage. large charging power.

The USB consortium is working towards a universal charger that can charge devices with a variety of different power requirements, as output power allows. Therefore, the output voltage and output current need to be preset to several levels or continuously adjustable to meet the needs of various devices. In the prior art, due to the large number of chip pins of the feedback control chip of the AC-to-DC (Alternate Current, AC; Direct Current, DC) converter, and the large number of compensating components around it, it cannot meet the latest requirements. The demand for miniaturization of market products.

This creative embodiment provides a feedback control chip and a switching power supply system, which can integrate a constant voltage feedback loop control module inside the feedback control chip, and integrate a compensation circuit inside the constant voltage feedback loop control module, so that the chip The constant voltage control function is integrated, the number of pins of the chip is reduced, and the number of peripheral compensation devices is reduced, the integration of the system is improved, the system components are saved, and the miniaturized design of the system is realized.

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

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

In a third aspect, an embodiment of the present invention provides a switching power supply system, including the optocoupler and the feedback control chip according to the first aspect and the second aspect.

The feedback control chip and the switching power supply system of this creative embodiment can integrate the constant voltage feedback loop control module inside the feedback control chip, and integrate the compensation circuit inside the constant voltage feedback loop control module, so that the chip integrates the The constant voltage control function reduces the number of pins of the chip and the number of peripheral compensation devices, improves the integration of the system, saves system components, and is conducive to realizing the miniaturization of the system.

100, 200: switching power supply system

110, 210: Rectifier bridge

120, 220: power converter

130, 230: drive chip

140, 240, 340, 440: feedback control chip

2401, 3401, 4401: Protocol communication module

2402, 3402, 4402: Output voltage and current protection control module

2403, 3403, 4403: Vo discharge control module

2404, 3404, 4404: UVLO/LDO discharge module

2405, 3405, 4405: Digital/MCU microcontroller units

2406, 2406’, 2406”: constant voltage/constant current feedback loop control module

2407, 3407, 4407: Load switch drive module

3406, 3406': constant voltage feedback loop control module

4406, 4406': constant current feedback loop control module

510: Voltage sampling module

511: Constant voltage loop transconductance error amplifier

512: Compensation circuit of constant voltage loop

513: Drive Capability Enhancement Buffer for Constant Voltage Loop

514: Constant Voltage Loop Voltage Amplifier

515: Constant voltage loop optocoupler drive isolation module (diode)

516: Output voltage discharge module

517: Output line voltage drop compensation module

518: Output current sampling and amplification module

519: Constant current loop transconductance error amplifier

519': Transconductance Error Amplifier

520: Compensation circuit of constant current loop

521: Drive Capability Enhancement Buffer for Constant Current Loop

522: Constant current loop voltage amplifier

523: Diode

C1, C2, C3, C4, C10, C20, Cfb, Co: Capacitor

DP/CC1, DN/CC2: protocol communication port

Gate: Load switch drive pin

GND: chip reference ground pin

IFB: Current Feedback Pin

ISN: Output Current Sense Negative Pin

ISP: Output current detection positive pin

M2: load switch

OPTO: Optocoupler drive pin

R1, R2, R20, Rcable, Ro, Rs, Rd, Rdis, Ropto: Resistance

VFB: Voltage Feedback Pin

VIN: Voltage

Vo: output voltage pin

Vref_cc: constant current reference voltage

Vref_cv: constant voltage reference voltage

In order to more clearly illustrate the technical solutions of this creative embodiment, the following will briefly introduce the diagrams that need to be used in this creative embodiment. Other schemas can be obtained from these schemas.

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

FIG. 2 shows a schematic structural diagram of a switching power supply system 200 provided by an embodiment of the present invention;

FIG. 3 shows a schematic diagram of the pins of the feedback control chip provided by the embodiment of the present invention;

FIG. 4 shows a schematic structural diagram of a feedback control chip capable of realizing constant voltage and constant current control provided by an embodiment of the present invention;

FIG. 5 shows a schematic structural diagram of a feedback control chip capable of realizing constant voltage control provided by an embodiment of the present invention;

FIG. 6 shows a schematic structural diagram of a feedback control chip capable of realizing constant current control provided by an embodiment of the present invention;

FIG. 7 shows a schematic structural diagram of the constant voltage/constant current feedback loop control module provided by the first embodiment of the present invention;

FIG. 8 shows a circuit structure diagram of an output voltage discharge module provided by another embodiment of the present invention;

FIG. 9 shows a schematic diagram of a circuit structure of an output line voltage drop compensation module provided by another embodiment of the present invention;

FIG. 10 shows a schematic structural diagram of the constant voltage/constant current feedback loop control module provided by the second embodiment of the present invention;

FIG. 11 shows a schematic structural diagram of the constant voltage feedback loop control module provided by the first embodiment of the present invention;

FIG. 12 shows a schematic structural diagram of the constant voltage feedback loop control module provided by the second embodiment of the present invention;

FIG. 13 shows a schematic structural diagram of the constant current feedback loop control module provided by the first embodiment of the present invention; and

FIG. 14 shows a schematic structural diagram of the constant current feedback loop control module provided by the second embodiment of the present invention.

The features and exemplary embodiments of various aspects of the present creation will be described in detail below. In order to make the purpose, technical solutions and advantages of the present creation more clear, the present creation will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present creation, and are not configured to limit the present creation. It will be apparent to those 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 invention by illustrating an example of the invention.

It should be noted that, in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any relationship between these entities or operations. any such actual relationship or sequence exists. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass a non-exclusive inclusion such that a process, method, article or device that includes a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element defined by the phrase "comprising..." does not preclude the presence of additional identical elements in a process, method, article, or device that includes the element.

In order to better understand the present invention, the following first introduces the switching power supply system provided by the prior art. Referring to FIG. 1 , FIG. 1 shows a schematic structural diagram of the switching power supply system 100 provided by the prior art. In the prior art, in order to meet the requirements of adjustable output voltage and current of new power supplies such as USB Type-C, a switching power supply system (eg, ACDC power supply) including a conventional feedback control chip is provided. As shown in FIG. 1 , the The switching power supply system 100 mainly includes a rectifier bridge 110, a power converter 120, a driving chip 130, a feedback control chip 140, etc., wherein, the feedback control chip 140 includes at least 10 pins. It is necessary to use more expensive packages such as SSOP10/QFN16, etc., and there are many peripheral compensation devices (for example, capacitors C1-C4 and resistors R1-R2, etc.), which lead to poor system reliability, high cost and disadvantage for product miniaturization.

Among them, the above pins include current feedback pin IFB, voltage feedback pin VFB, optocoupler driving pin OPTO, output current detection positive pin ISP, output current detection negative pin ISN, load switch driving pin GATE, chip reference Ground pin GND, output voltage pin VO, protocol communication port DP/CC1 and protocol communication port DN/CC2, etc.

Therefore, in order to solve the problems existing in the prior art, the present invention provides a novel switching power supply system. First, the switching power supply system provided by the embodiment of the present invention will be introduced below.

Referring to FIG. 2, FIG. 2 shows a switching power supply provided by an embodiment of the present invention A schematic diagram of the structure of the system 200 . As shown in FIG. 2, the switching power supply system 200 mainly includes a rectifier bridge 210, a power converter 220, a driving chip 230, a feedback control chip 240, etc., wherein the feedback control chip 240 may include 8 pins, for example, an optocoupler Drive pin OPTO, output current detection positive pin ISP, output current detection negative pin ISN, load switch drive pin GATE, chip reference ground pin GND, output voltage pin VO, protocol communication port DP/CC1 and protocol communication DN/CC2, etc., are less than the number of pins included in the feedback control chip 140 in the prior art, for example, it at least lacks the voltage feedback pin VFB and the current feedback pin IFB, and the feedback control chip 240 is a highly integrated A feedback control chip with adjustable multi-level output voltage and output current, and the chip 240 integrates the feedback loop inside the chip, which can use inexpensive packages such as the most commonly used SOP8, and the chip 240 will also be constant The resistors, capacitors, etc. of voltage, constant current, or loop compensation of constant voltage and constant current are integrated inside the chip, so that only one resistor is needed around the chip to the optocoupler, which can minimize the interference of the system layout, and Improving the integration degree of the system and saving the components of the system is conducive to realizing the miniaturization design of the system.

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

In addition, since the feedback control chip 240 provided by this creative embodiment integrates a complete feedback loop inside the chip, the chip can additionally add many loop-related loops. Features. For example, the built-in functions of the feedback control chip 240 may be as follows: output constant voltage control and loop feedback, output constant current control and loop feedback, output line voltage drop compensation, output voltage dynamic enhancement, optocoupler driving maximum current clamp Element, chip soft start, output voltage and current soft switching, the function of discharging the output capacitor when the output voltage is switched, etc. Meanwhile, the feedback control chip 240 can also integrate various secondary output protections, such as Overvoltage Protection (OVP), Under-Voltage Protection (UVP), Over Current Protection (OCP) ), and/or Optical Line Protection (OLP), etc.

The feedback control chip provided in the embodiment of the present invention can be applied to, for example, an offline switching power supply system (offline AC to DC). The main power topology can include, but is not limited to, a flyback converter. Any suitable offline switching power supply topology can adopt this invention. The structure of the switching power supply system of the feedback control chip provided by the embodiment is shown in FIG. 2 , and the pins of the feedback control chip are shown in FIG. 3 , which shows the pins of the feedback control chip provided by the embodiment of the present invention. Schematic. It should be noted that the systems and wafers shown in Figures 2 and 3 are provided as examples only. The number of pins of the feedback control chip provided in this creative embodiment is not limited to 8, which can be changed according to the actual system application. For example, the number of pins of the chip can be expanded accordingly. On the basis of the pins, several general-purpose input/output (General-Purpose Input/Output, GPIO) pins are added.

As an example, the feedback control chip provided by this creative embodiment mainly includes the following pins: a first pin (for example, a system output voltage detection and discharge pin (for example, a VO pin)), a second pin (for example, a pin for detecting and discharging the output voltage of the system) , the output current sampling pin (such as ISN, ISP pin), the third pin (for example, the drive pin of the optocoupler (such as the OPTO pin)), the fourth pin (for example, the drive pin of the load switch (such as GATE pin), the fifth pin (for example, the pin for fast charging/PD protocol communication (such as DP/CC1 pin)), and the sixth pin (for example, the pin for fast charging/PD protocol communication) (such as DP/CC2 pin)) and so on. The function of each of the above pins will be described below with reference to FIG. 2 .

As an example, the ISP pin can be connected to the output current sampling resistor The first end of Rs is used to realize constant current control and OCP control of the wafer.

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

As an example, the Vo pin can be connected to the first terminal (eg, the positive electrode) of the output capacitor Co, for realizing the constant voltage control of the wafer and the discharge control of the output voltage switching process.

As an example, the OPTO pin may be connected to the first end of the resistor Ropto (eg, the end of the resistor away from the optocoupler) for control of the system loop.

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

As an example, the GATE pin may be connected to the gate of load switch M2. It should be noted that in some embodiments, as shown in FIG. 2 , the load switch M2 is illustrated with an NMOS as an example, and the load switch M2 is connected to the positive terminal of the output. However, in other embodiments, the load switch may be a PMOS, and the load switch may be connected to the negative terminal of the output, which is not limited by the present invention. In still other embodiments, the output voltage Vo can be directly output to the load. In this case, there is no load switch in the system. At this time, according to the needs of different switch types, the GATE pin can be left floating and can be connected to the reference via a resistor. ground, can also be connected directly to the reference ground.

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

As an example, the feedback control chip provided in this creative embodiment may include an output voltage pin and an optocoupler driving pin, and may also include a constant voltage feedback loop control module, the first end of which may be connected to the output voltage pin, The second end can be connected to the optocoupler driving pin, wherein the constant voltage feedback loop control module can include a compensation circuit, which is used to keep the system in the preset time domain performance and frequency domain performance.

As another example, the feedback control chip provided in this creative embodiment may include an optocoupler driving pin, an output current detection positive pin, and an output current detection negative pin, and may also include a constant current feedback loop control module, which The first end can be connected to the output current detection positive pin, the second end can be connected to the output current detection negative pin, and the third end can be connected to the optocoupler drive pin, wherein the constant current feedback loop control module can include: The compensation circuit is used to make the system in the preset time domain performance and frequency domain performance.

As an example, the feedback control chip provided in this creative embodiment may include an output voltage pin, an output current detection positive pin, an output current detection negative pin, and an optocoupler driving pin, and may also include a constant voltage/constant current feedback loop circuit control module, wherein the first end of the constant voltage/constant current feedback loop control module can be connected to the output voltage pin, the second end can be connected to the output current detection positive pin, and the third end can be connected to The output current detection negative pin, and the fourth terminal can be connected to the optocoupler driving pin, wherein the constant voltage/constant current feedback loop control module can include a compensation circuit for making the system in a preset time domain performance and frequency domain performance.

It can be seen that, the above solutions provided by the present creative embodiments integrate the constant voltage and/or constant current feedback loop control module inside the feedback control chip, and integrate the compensation circuit into the constant voltage and/or constant current feedback loop control Inside the module, the chip integrates constant voltage and/or constant current control functions, and at the same time reduces the number of pins on the chip, reduces the number of peripheral compensation devices, improves the integration of the system, saves system components, and is beneficial to Realize the miniaturized design of the system.

The feedback control chip 240 provided by the present invention will be described in detail below with reference to the first embodiment. Specifically, referring to FIG. 4 , FIG. 4 shows the feedback control chip 240 capable of realizing constant voltage and constant current control provided by the embodiment of the present invention. Schematic.

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 , and a UVLO/LDO discharge module A group 2404, a digital/MCU (Microcontroller Unit, MCU) micro-control unit 2405, a constant voltage/constant current feedback loop control module 2406, and a load switch drive module 2407, etc.

The first end of the protocol communication module 2401 can be connected to the DP/CC1 Communication port, the second end can be connected to the DN/CC2 communication port, the third end can be connected to the first end of the microcontroller unit 2405, the first end of the output voltage and current protection control module 2402 can be connected to the microcontroller unit 2405 The second end of the VO discharge control module 2403 can be connected to the third end of the microcontroller unit 2405, the first end of the UVLO/LDO discharge module 2404 can be connected to the VO pin, and the second end can be connected to the VO pin. To the fourth end of the microcontroller unit 2405, the first end, the second end and the third end of the constant voltage/constant current feedback loop control module 2406 can be connected to the OPTO pin, the ISP pin and the ISN pin, respectively, The fourth terminal can be connected to the VO pin for receiving the output current of the system via the ISP pin and the ISN pin, and the output voltage of the system via the VO pin, and the fifth terminal can be connected to the fifth terminal of the microcontroller unit 2405. terminal, the first terminal of the load switch driving module 2407 can be connected to the GATE pin, and the second terminal can be connected to the sixth terminal of the microcontroller 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-mentioned chip 240 can be applied in a switching power supply system for realizing constant voltage control and constant current control.

The feedback control chip provided by the present invention will be described in detail below with reference to the second embodiment. Specifically, referring to FIG. 5 , FIG. As shown in FIG. 5 , the feedback control chip 340 may include, for example, the following modules: 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 micro control unit 3405, constant voltage feedback loop control module 3406 and load switch drive module 3407, etc.

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

It can be seen that the feedback control chip 340 includes a constant voltage feedback loop control module 3406, so that the above-mentioned chip 340 can be applied in a switching power supply system for realizing constant voltage control.

The feedback control chip provided by the present invention is described in detail below with reference to the third embodiment. Specifically, referring to FIG. 6 , FIG. 6 shows a schematic structural diagram of the feedback control chip capable of realizing 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: 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 micro control unit 4405, constant current feedback loop control module 4406 and load switch drive module 4407, etc.

The first end of the protocol communication module 4401 can be connected to the DP/CC1 communication port, the second end can be connected to the DN/CC2 communication port, and the third end can be connected to the first end of the microcontroller unit 4405. The output voltage and The first end of the current protection control module 4402 can be connected to the second end of the micro-control unit 4405, the first end of the Vo discharge control module 4403 can be connected to the third end of the micro-control unit 4405, and the UVLO/LDO discharge module The first end of 4404 can be connected to the VO pin, the second end can be connected to the fourth end of the microcontroller unit 4405, the first end, the second end and the third end of the constant current feedback loop control module 4406 can be respectively Connected to the OPTO pin, ISP pin and ISN pin, used to receive the output current of the system via the ISP pin and ISN pin, the fourth terminal can be connected to the fifth terminal of the microcontroller unit 2405, the load switch drive module The first terminal of 4407 can be connected to the GATE pin and the second terminal can be connected to the sixth terminal of the microcontroller unit 4405.

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

The control mode of the constant voltage/constant current feedback loop shown in FIG. 4 is described below in conjunction with FIG. 7 Group 2406 is introduced in detail. Specifically, FIG. 7 shows a schematic structural diagram of the constant voltage/constant current feedback loop control module provided by 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 between the ISN, ISP pins and the OPTO pin the second branch of the Constant current control.

In some embodiments, the first branch may include an output voltage sampling module 510, a constant voltage loop transconductance error amplifier (Operational Transconductance Amplifier, OTA) 511, a constant voltage loop compensation circuit 512, a constant voltage loop The driving capability enhancement buffer 513, the constant voltage loop voltage amplifier 514, and the constant voltage loop optocoupler drive isolation module 515 (eg, diode), etc., it should be noted that any appropriate module with isolation function is included in this Within the scope of creation, a diode is used as an example for description below. In other embodiments, the first branch may further include an output voltage discharge module 516 and an output line voltage drop compensation module 517 and the like.

The first end of the output voltage sampling module 510 can be connected to the VO pin, the second end can be connected to the reference ground, and the first end of the constant voltage loop transconductance error amplifier (OTA) 511 (for example, the negative phase input terminal) can be connected to the third terminal of the output voltage sampling module 510, the second terminal (eg, the non-inverting input terminal) can be used to receive the constant voltage reference voltage Vref_cv, and the first terminal of the compensation circuit 512 of the constant voltage loop can be connected to the third terminal (eg, output terminal) of the constant voltage loop transconductance error amplifier (OTA) 511, the second terminal may be connected to the first terminal of the driving capability enhancement buffer 513 of the constant voltage loop, the constant voltage loop The first terminal of the circuit voltage amplifier 514 may be connected to the second terminal of the buffer 513, the second terminal may be connected to the first terminal (eg, the positive pole) of the diode 515, and the second terminal (eg, the positive pole) of the diode 515 may be connected. The negative pole) can be connected to the OPTO pin, and the output voltage discharge module 516 can be connected between the Vo pin and the reference ground, and both ends of the output line voltage drop compensation module 517 can be connected to both ends of the resistor Rd.

The functions of the above modules are described in detail below by way of examples. As an example, referring to FIG. 2 and FIG. 7 , the output voltage sampling module 510 can be used to The output voltage of the system is divided and sampled, and the output voltage is reduced to a reasonable voltage range for the post-stage adjustment module. For example, the output voltage sampling module 510 may include a voltage divider module, such as a resistor R1 and a resistor Rd connected in series between the VO pin and the reference ground. The main function of the output voltage sampling module 510 is to participate in the subsequent constant voltage Voltage loop feedback loop, dynamic enhancement compensation and OVP/UVP protection.

Specifically, the dynamic enhancement compensation function is realized by the following methods: detecting the output voltage, and setting a reasonable output voltage range, once it is detected that the output voltage exceeds the preset output voltage range, the dynamic enhancement circuit is activated, through Sink/source current to the output of the compensation circuit 512 of the latter stage constant voltage loop to pull the output voltage back to a preset output voltage range.

As an example, a constant voltage loop transconductance error amplifier (OTA) 511 may be used to compare the sampled output voltage with the constant voltage reference voltage Vref_cv to generate 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 ), etc., which is not limited in the present invention. During startup or when the output voltage is switched, the soft-start and output voltage buck-boost soft switching can be achieved by means of Vref_cv soft-rise and soft-drop. 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 (eg, the range between Vgm_min and Vgm_max). When the output voltage sampling module 510 detects that the output voltage exceeds the dynamic enhancement threshold range, it can sink/source the output of the transconductance error amplifier (OTA) 511 to pull the output voltage back to the preset output voltage scope.

As an example, the compensation circuit 512 of the constant voltage loop can be used to bring the system to reasonable time domain performance 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 the output terminal of the transconductance error amplifier (OTA) 511 and the reference ground Between the capacitor C2, where the resistor R2 and the capacitor C1 are connected in series, reasonable time-domain performance and frequency-domain performance can be obtained by setting reasonable resistor and capacitor values. Without limitation, any other suitable circuits that can realize the compensation function are included in the within the range. Specifically, the time-domain performance can be determined according to the user's specification requirements, while the frequency-domain performance can be scanned by a loop analyzer using methods such as small-signal injection analysis. Generally, stable system open-loop phase margin may require Above 45 degrees, for example, and the gain margin may need to be above 10~12dB, for example.

As an example, since the drive capability of some transconductance error amplifiers (OTA) 511 may be very weak, the drive capability of the transconductance error amplifier (OTA) 511 can be enhanced by setting the drive 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 meet the requirements of driving an external optocoupler, in this case, the constant voltage loop voltage amplifier 514 can be used to The output voltage range of the transconductance error amplifier (OTA) 511 is increased, so that a sufficient driving voltage range can be provided to fully meet the needs of driving the external optocoupler, and the maximum value of the driving current can be clamped to the set value inside the chip. However, in other embodiments, since the output voltage range of some transconductance error amplifier (OTA) 511 can fully meet the needs of driving an external optocoupler, in this case, the constant voltage loop voltage amplifier 514 is not needed to increase the Large output voltage range.

As an example, in order to further improve the chip performance, for example, in order to prevent mutual interference between the two loop systems in different modes, the isolation module 515 and the constant current loop optocoupler driver can be set by setting the constant voltage loop optocoupler driver The isolation module 523 is used to isolate the constant voltage loop and the constant current loop.

In some embodiments, in order to further improve the performance of the constant voltage loop, an output voltage discharge module 516 can also be provided, and the output voltage discharge module 516 can be used to switch the output through the constant voltage reference voltage Vref_cv under no-light load conditions turn on at voltage. As a dummy load of the system, when the output voltage decreases, the output voltage discharge module 516 can be used to rapidly discharge the output voltage to discharge to a set voltage range, so as to meet the system step-down time and performance specifications. When the output voltage is boosted, the output voltage discharge module 516 can be used to suppress the overshoot of the output voltage, so that the output voltage can return to the set voltage range as soon as possible.

It should be noted that in the embodiment shown in Figure 7, the output voltage discharge mode The group 516 realizes the discharge 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 discharge module provided by another embodiment of the present invention, wherein the output voltage discharge module 516 is connected through a resistor (eg, , Rdis) to achieve the discharge function, any other appropriate circuit with the discharge function is within the scope of this creation.

In some embodiments, in order to further improve the performance of the constant voltage loop, since the output wire may cause the line terminal voltage drop, it may be necessary to set the output line voltage drop compensation module 517 to compensate for the line voltage drop. The output voltage of the output current sampling and amplifying module 518 (which contains information related to the output current) is multiplied by an appropriate scaling parameter k, and is provided by means of a voltage controlled current source (VCCS) or the like. For the compensation current of the output wire, make the compensation current flow into the sampling point of the output voltage sampling module 510, that is, the common terminal of the resistor R1 and the resistor Rd. Compensation for voltage drop, so that the line voltage is maintained at the set value over the full load range.

However, in other embodiments, referring to FIG. 9 , FIG. 9 shows a schematic diagram of the circuit structure of the output line voltage drop compensation module provided by another embodiment of the present invention. It can be seen from FIG. A voltage source proportional to the output current is superimposed on one input terminal (for example, the negative input terminal) of the error amplifier (OTA) 511, that is, a voltage proportional to the output current is superimposed on the constant voltage reference voltage Vref_cv to compensate The line terminal voltage drop caused by the output wire keeps the line voltage at the set value throughout the full load range.

In some embodiments, the second branch may include an output current sampling and amplification module 518, a constant current loop transconductance error amplifier (OTA) 519, a constant current loop compensation circuit 520, and a constant current loop driving capability Enhanced buffer 521, constant current loop voltage amplifier 522, and constant current loop optocoupler drive isolation module 523 (eg, diode), etc. It should be noted that any suitable module with isolation function is included in this creation. range, the diode is used as an example for description below.

Wherein, the first end of the output current sampling and amplification module 518 (for example, The negative input terminal) can be connected to the ISN pin, the second terminal (eg, the non-inverting input terminal) can be connected to the ISP pin, and the first terminal (eg, negative input terminal) of the constant current loop transconductance error amplifier (OTA) 519 phase input terminal) can be connected to the third terminal (eg, the output terminal) of the output current sampling and amplification module 518, and the second terminal (eg, the non-inverting input terminal) can be used to receive the constant current reference voltage Vref_cc, the constant current loop The first terminal of the compensation circuit 520 of the circuit may be connected to the third terminal (eg, the output terminal) of the transconductance error amplifier (OTA) 519, and the second terminal may be connected to the first terminal of the driving capability enhancement buffer 521 of the constant current loop. One end, the first end of the constant current loop voltage amplifier 522 may be connected to the second end of the buffer 521, and the second end may be connected to the first end (eg, the positive electrode) of the diode 523, the The second terminal (eg, negative) can be connected to the OPTO pin.

The functions of the above modules are described in detail below by way of examples. As an example, referring to FIG. 2 and FIG. 7 , the output current sampling and amplification module 518 can be used to measure the voltage on the sampling resistor Rs (see FIG. 2 ). Sampling is performed, wherein the current on the sampling resistor Rs is the output current, and the sampled voltage is amplified to an appropriate voltage range by the voltage amplification module therein for use in the subsequent stage. The main function of the output current sampling and amplification module 518 is to participate in the latter-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 the constant current reference voltage Vref_cc to generate 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 ), etc., which is not limited in the present invention. When the output current is switched, the soft switching of the current size can be realized by means of a soft rise or a soft fall of Vref_cc.

As an example, the compensation circuit 520 of the constant current loop can be used to keep the system in reasonable time domain performance and frequency domain performance. For example, the compensation current 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 the output terminal of the transconductance error amplifier (OTA) 519 and the reference ground Between the capacitor C20, where the resistor R20 and capacitor C10 are connected in series, can be set by It should be noted that this creation does not limit the compensation circuit, and any other suitable circuits that can realize the compensation function are within the scope of this creation. Specifically, the time-domain performance can be determined according to the user's specification requirements, while the frequency-domain performance can be scanned by a loop analyzer using methods such as small-signal injection analysis. Generally, stable system open-loop phase margin may require Above 45 degrees, for example, and the gain margin may need to be above 10~12dB, for example.

As an example, since the drive capability of some transconductance error amplifiers (OTA) 519 may be very weak, the drive capability of the transconductance error amplifier (OTA) 519 can be enhanced by setting the drive 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 meet the needs of driving an external optocoupler, in this case, the constant current loop voltage amplifier 522 can be used to The output voltage range of the guided error amplifier (OTA) 519 is increased, so that a sufficient driving voltage range can be provided to fully meet the needs of driving an external optocoupler, and the maximum value of the driving current can be clamped to a set value inside the chip. However, in other embodiments, the constant current loop voltage amplifier 522 is not needed to increase the Large output voltage range.

As an example, in order to further improve the chip performance, for example, in order to prevent mutual interference between the two loop systems in different modes, the isolation module 515 and the constant current loop optocoupler driver can be set by setting the constant voltage loop optocoupler driver The isolation module 523 is used to isolate the constant voltage loop and the constant current loop.

It should be noted that the constant voltage/constant current feedback loop control module 2406 shown in FIG. 7 is only provided as an example, and other implementations of the constant voltage/constant current feedback loop control module may 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 by 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, in which the same element sampling phase The main difference between the two is that the constant voltage/constant current feedback loop control module 2406" reduces the constant voltage/constant current feedback loop control module 2406' based on the voltage loop voltage amplifier 514 and constant current loop voltage amplifier 522, and the two input terminals of the transconductance error amplifier (OTA) 511' and the transconductance error amplifier (OTA) 519' are interchanged, for example, the transconductance error amplifier (OTA) 511' and the transconductance error amplifier (OTA) 519' shown in FIG. The negative-phase input terminal of the conducting error amplifier (OTA) 511 can be connected to the third terminal of the output voltage sampling module 510, and its positive-phase input terminal can be used to receive the constant voltage reference voltage Vref_cv, and the transconductance error shown in FIG. 10 The non-inverting input terminal of the amplifier (OTA) 511 ′ can be connected to the third terminal of the output voltage sampling module 510 , and its negative-phase input terminal can be used to receive the constant voltage reference voltage Vref_cv; and the transconductance error amplifier shown in FIG. 7 The negative-phase input terminal of the (OTA) 519 can be connected to the third terminal (eg, the output terminal) of the output current sampling and amplification module 518 , and the positive-phase input terminal thereof can be used to receive the constant current reference voltage Vref_cc, and as shown in FIG. 10 The non-inverting input terminal of the shown transconductance error amplifier (OTA) 519' can be connected to the third terminal (eg, the output terminal) of the output current sampling and amplification module 518, and its negative-phase input terminal can be used to receive the constant current reference The voltage Vref_cc, that is, the constant voltage/constant current feedback loop control module 2406" can be applied in a scenario where the output voltage range of the transconductance error amplifier (OTA) can fully meet the requirements of driving an external optocoupler.

However, it should be noted that the embodiment shown in FIG. 10 should be construed as limiting and is not intended to limit the present creation. For example, in the first embodiment, the constant voltage/constant current feedback loop control module can reduce the output voltage discharge module on the basis of the constant voltage/constant current feedback loop control module 2406" shown in FIG. 10 . 516 and/or the output line voltage drop compensation module 517. In the second embodiment, the constant voltage/constant current feedback loop control module 2406" shown in FIG. On the basis of the constant current feedback loop control module, a constant voltage loop voltage amplifier 514 is added between the constant voltage loop optocoupler drive isolation module 515 and the driving capability enhancement buffer 513 of the constant voltage loop, and here In this case, the two input terminals of the transconductance error amplifier (OTA) 511' shown in OTA) 511 consistent. In the third embodiment, 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, an additional Constant current loop optocoupler driver isolation module 523 and constant current loop driver The constant current loop voltage amplifier 522 between the dynamic capability enhancement buffers 521, and in this case, the two inputs of the transconductance error amplifier (OTA) 519' shown in FIG. 10 need to be interchanged, that is, its The states of the two inputs need to be consistent with the transconductance error amplifier (OTA) 519 shown in Figure 7.

In order to simplify the description, the corresponding functions of the components in FIG. 10 are similar to the functions of the corresponding components in FIG. 7 . Since the functions of each element have been described in detail in FIG. 7 , they are not repeated here.

The constant voltage feedback loop control module 3406 shown in FIG. 5 will be introduced in detail below with reference to FIG. 11 . Specifically, FIG. 11 shows a schematic structural diagram of the constant voltage feedback loop control module provided by 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 marked with the same drawings. 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 constant voltage loop compensation circuit 512, a constant voltage loop driving capability enhancement buffer 513, and a constant voltage loop voltage amplifier 514 etc. In other embodiments, the constant voltage feedback loop control module 3406' may further include an output voltage discharge module 516, an output line voltage drop compensation module 517, and the like. The difference is that the isolation diode 515 may not be provided at this time.

In order to simplify the description, the corresponding functions of the components in FIG. 11 are similar to the functions of the corresponding components in FIG. 7 . Since the functions of each element have been described in detail in FIG. 7 , they are not repeated here.

It should be noted that the constant voltage feedback loop control module 3406' shown in FIG. 11 is only provided 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 by 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 . The main difference is that the constant voltage feedback loop control module 3406" is in constant On the basis of the voltage feedback loop control module 3406', the output voltage discharge module 516, the output line voltage drop compensation module 517, the constant voltage loop voltage amplifier 514, and the two transconductance error amplifier (OTA) 511 are reduced. The input terminals are interchanged, that is, the non-inverting input terminal of the transconductance error amplifier (OTA) 511 can be connected to the output terminal of the output voltage sampling module 510, and the negative-phase input terminal can be used to receive the reference voltage Vref_cv, constant voltage feedback loop control The module 3406" can be used in scenarios where the output voltage range of the transconductance error amplifier (OTA) can fully meet the needs of driving an external optocoupler.

In order to simplify the description, the corresponding functions of the components in FIG. 12 are similar to the functions of the corresponding components in FIG. 7 . Since the functions of each element have been described in detail in FIG. 7 , they are not repeated here.

The following describes the constant current feedback loop control module 4406 shown in FIG. 6 in detail with reference to FIG. 13 . Specifically, FIG. 13 shows a schematic structural diagram of the constant current feedback loop control module provided by 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 marked with the same drawings. ' may include an output current sampling and amplification module 518, a constant current loop transconductance error amplifier (OTA) 519, a constant current loop compensation circuit 520, a constant current loop driving capability enhancement buffer 521, and a constant current loop voltage amplifier 522, etc. The difference is that the isolation diode 523 may not be provided at this time.

In order to simplify the description, the corresponding functions of the components in FIG. 13 are similar to those of the corresponding components in FIG. 7 . Since the functions of each element have been described in detail in FIG. 7 , they are not repeated here.

It should be noted that the constant current feedback loop control module 4406' shown in FIG. 13 is only provided as an example, and there may be other implementations of the constant current feedback loop control module. For example, referring to FIG. 14, FIG. 14 shows A schematic structural diagram of the constant current feedback loop control module provided by the second embodiment of the present invention.

As shown in Figure 14, the constant current feedback loop control module 4406" is similar to the figure The constant current feedback loop control module 4406' shown in 13, in which the same components are sampled with the same drawing marks, the difference between the two is mainly that the constant current feedback loop control module 4406" is in constant current On the basis of the feedback loop control module 4406 ′, the constant current loop voltage amplifier 522 is reduced, and the two input terminals of the transconductance error amplifier (OTA) 519 are interchanged, that is, the positive phase of the transconductance error amplifier (OTA) 519 The input terminal can be connected to the output terminal of the output current sampling and amplifying module 518, the negative phase input terminal can be used to receive the reference voltage Vref_cc, and the constant current feedback loop control module 4406″ can be applied to the transconductance error amplifier (OTA) The output voltage range can fully meet the needs of driving external optocouplers in scenarios.

In order to simplify the description, the corresponding functions of the components in FIG. 14 are similar to those of the corresponding components in FIG. 7 . Since the functions of each element have been described in detail in FIG. 7 , they are not repeated here.

In summary, the present invention provides a feedback control chip and a control method thereof that can be applied to, for example, an offline switching power supply system. The feedback control chip can compare an output voltage or current with a constant voltage reference voltage or current through a transconductance error amplifier (OTA). Amplify the error between and use a buffer to increase the drive capability of the transconductance error amplifier (OTA), optionally an op amp can then be used to adjust the voltage to drive the optocoupler diode, and The feedback signal is passed to the primary side PWM chip.

Through the above technical solution, the control loop can be integrated inside the chip, and the chip can be integrated with the following functions: constant voltage control, constant current control, output line voltage drop compensation, output voltage dynamic enhancement, output voltage soft start, output The voltage/current realizes functions such as soft switching and discharging the output capacitor during buck-boost. This highly integrated feature of the chip can meet the application of multiple output voltages such as PD/QC.

To be clear, the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above-described embodiments, several specific steps are described and shown as examples. However, the method process of the present creation is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change any of the steps after comprehending the spirit of the present creation. sequence between.

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 can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), suitable firmware, a plug-in program, a function card, and the like. When implemented in software, elements of the present authoring are programs or pieces of code that are used to perform the desired tasks. The program, or segments of program code, can be stored on a machine-readable medium or transmitted over a transmission medium or communication link by a data signal carried in a carrier wave. A "machine-readable medium" may include any medium that can store or transmit information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM (Read-Only Memory, ROM, read-only memory), flash memory, erasable ROM (Erasable Read Only Memory, EROM), floppy disks , CD-ROM (Compact Disc Read-Only Memory, CD-ROM, CD-ROM), optical discs, hard disks, optical media, radio frequency (Radio Frequency, RF) links, and so on. The code snippets may be downloaded via a computer network such as the Internet, an intranet, or the like.

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

The above are only specific implementations of the present creation. Those skilled in the art can clearly understand that, for the convenience and conciseness of the description, the specific working process of the above-described systems, modules and units can be implemented with reference to the aforementioned methods. The corresponding process in the example will not be repeated here. It should be understood that the protection scope of this creation is not limited to this, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by this creation, and these modifications or replacements should be covered in within the scope of protection of this work.

340: Feedback control chip

3401: Protocol communication module

3402: Output voltage and current protection control module

3403: Vo Discharge Control Module

3404: UVLO/LDO discharge module

3405: Digital/MCU Microcontroller Unit

3406: Constant voltage feedback loop control module

3407: Load switch driver module

DP/CC1, DN/CC2: protocol communication port

Gate: Load switch drive pin

GND: chip reference ground pin

OPTO: Optocoupler drive pin

Vo: output voltage pin

Claims (13)

A feedback control chip, applied to a switching power supply system, is characterized in that, the feedback control chip includes an output voltage pin and an optocoupler drive pin, and further includes: A constant voltage feedback loop control module, the first end of which is connected to the output voltage pin, and the second end is connected to the optocoupler drive pin, wherein, The constant voltage feedback loop control module includes a first compensation circuit. The feedback control chip according to claim 1, wherein the feedback control chip further includes an output current detection positive pin and an output current detection negative pin, and further includes: A constant current feedback loop control module, the first end of which is connected to the positive output current detection pin, the second end is connected to the negative output current detection pin, and the third end is connected to the optocoupler driving pin ,in, The constant current feedback loop control module includes a second compensation circuit. The feedback control chip according to claim 1, wherein the constant voltage feedback loop control module further comprises: an output voltage sampling module, the first end of which is connected to the output voltage pin, and the second end is connected to the reference ground; a first transconductance error amplifier, the first end of which is connected to the third end of the output voltage sampling module, and the second end is used for receiving the first reference voltage; and a first buffer, the first end of which is connected to the third end of the first transconductance error amplifier via the first compensation circuit, and the second end is connected to the optocoupler driving pin. The feedback control chip according to claim 1, wherein the constant voltage feedback loop control module further comprises: an output voltage sampling module, the first end of which is connected to the output voltage pin, and the second end is connected to the reference ground; the first transconductance error amplifier, the first end of which is connected to the third part of the output voltage sampling module terminal, the second terminal is used for receiving the first reference voltage; a first buffer, the first end of which is connected to the third end of the first transconductance error amplifier via the first compensation circuit; and A first voltage amplifier, the first end of which is connected to the second end of the first buffer, and the second end is connected to the optocoupler driving pin. The feedback control chip according to claim 3 or 4, wherein the constant voltage feedback loop control module further comprises: The first end of the discharge module is connected to the output voltage pin, and the second end is connected to the reference ground, wherein the discharge module includes a constant current source or a resistor. The feedback control chip according to claim 3 or 4, wherein the constant voltage feedback loop control module further comprises: The output line voltage drop compensation module, the first end of which is connected to the third end of the output voltage sampling module, the second end is connected to the reference ground, or the first end is connected to the first transconductance error amplifier The second terminal is connected to a reference ground via a voltage source providing the first reference voltage. The feedback control chip according to claim 2, wherein the feedback control chip further comprises 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 through the The second isolation module is connected to the optocoupler driving pin. The feedback control chip according to claim 7, wherein the constant current feedback loop control module further comprises: an output current sampling module, the first end of which is connected to the positive output current detection pin, and the second end is connected to the negative output current detection pin; a second transconductance error amplifier, the first end of which is connected to the third end of the output current sampling module, and the second end is used for receiving the second reference voltage; and A second buffer, the first end of which is connected to the third end of the second transconductance error amplifier via the second compensation circuit, and the second end is connected to the optocoupler driver via the second isolation module foot. The feedback control chip according to claim 7, wherein the constant current feedback loop control module further comprises: an output current sampling module, the first end of which is connected to the output current detection positive pin, and the first end is connected to the output current detection positive pin; The two terminals are connected to the negative pin of the output current detection; the second transconductance error amplifier, the first terminal of which is connected to the third terminal of the output current sampling module, and the second terminal is used for receiving the second reference voltage; two buffers, the first terminal of which is connected to the third terminal of the second transconductance error amplifier via the second compensation circuit; and a second voltage amplifier, the first terminal of which is connected to the third terminal of the second buffer Two terminals, the second terminal is connected to the optocoupler driving pin via the second isolation module. A feedback control chip, applied to a switching power supply system, is characterized in that, the feedback control chip further comprises an optocoupler driving pin, an output current detection positive pin and an output current detection negative pin, and further comprises: a constant current feedback loop circuit control module, the first end of which is connected to the output current detection positive pin, the second end is connected to the output current detection negative pin, and the third end is connected to the optocoupler driving pin, wherein all the The constant current feedback loop control module includes a third compensation circuit. The feedback control chip of claim 10, wherein the constant current feedback loop control module further comprises: an output current sampling module, the first end of which is connected to the output current detection positive pin; The two ends are connected to the negative pin of the output current detection; the third transconductance error amplifier, the first end of which is connected to the third end of the output current sampling module, and the second end is used for receiving the third reference voltage; and A third buffer, the first end of which is connected to the third end of the third transconductance error amplifier via the third compensation circuit, and the second end of which is connected to the optocoupler driving pin. The feedback control chip according to claim 10, wherein the The constant current feedback loop control module further includes: an output current sampling module, the first end of which is connected to the positive output current detection pin, and the second end is connected to the negative output current detection pin; a third transconductance an error amplifier, the first end of which is connected to the third end of the output current sampling module, the second end is used for receiving the third reference voltage; the third buffer, the first end of which is connected to the third compensating circuit a third end of the third transconductance error amplifier; and a third voltage amplifier, the first end of which is connected to the second end of the third buffer, and the second end is connected to the optocoupler driving pin. A switching power supply system, characterized in that it includes the optocoupler connected to the optocoupler driving pin of the feedback control chip according to any one of claim 1 to claim 12.

Images