TWM626774U - Off-line switch power circuit and feedback control chip thereof - Google Patents

Abstract

An off-line switching power supply circuit and its feedback control chip are provided. In the feedback control chip, the feedback loop control module includes an output voltage detection unit, an output voltage feedback loop operational transconductance amplifier, an output voltage feedback loop compensation circuit, and an output voltage feedback loop optocoupler drive circuit. The output voltage detection The first terminal of the unit is connected to the output voltage detection pin, the second terminal is connected to the first terminal of the output voltage feedback loop operational transconductance amplifier, and the third terminal is connected to the second terminal of the output voltage feedback loop operational transconductance amplifier and grounded, the third terminal of the output voltage feedback loop operational transconductance amplifier is connected to the first terminal of the output voltage feedback loop compensation circuit and the first terminal of the output voltage feedback loop optocoupler drive circuit, the output voltage feedback loop compensation The second terminal of the line is grounded, the second terminal of the output voltage feedback loop optocoupler driving line is grounded, and the third terminal is connected to the optocoupler driving pin.

Description

Off-line switching power supply circuit and its feedback control chip

This creation relates to the field of integrated circuits, in particular to an off-line switching power supply circuit and its feedback control chip.

In recent years, as mobile devices such as smartphones, tablets, and laptops have larger screens and faster processors, the power consumption of mobile devices has become large. In order to meet the user's requirement for the standby time of the mobile device, the capacity of the power supply battery of the mobile device is constantly increasing. In order to reduce the charging time of the power supply battery of the mobile device, the charging power of the mobile device is correspondingly increased. However, due to the physical limitation of the maximum current of the Universal Serial Bus (USB), the charger can only provide greater charging power for the mobile device by increasing the output voltage.

The USB consortium is working toward a universal charger, that is, one that can charge devices with a variety of different charging power requirements. In the prior art, due to the large number of pins and peripheral compensation components of the feedback control chip of the AC/Direct Current (AC/Direct Current, DC) switching power supply circuit used as such a charger, As a result, it cannot meet the needs of miniaturization.

In view of one or more of the above problems, the present invention provides an off-line switching power supply circuit and a feedback control chip thereof.

A feedback control chip for an offline switching power supply circuit according to an embodiment of the present invention includes an output voltage detection pin, an optocoupler driving pin, and a feedback loop control module, wherein: the feedback loop control module includes an output voltage a detection unit, an output voltage feedback loop operational transconductance amplifier, an output voltage feedback loop compensation circuit, and an output voltage feedback loop optocoupler drive circuit, the first terminal of the output voltage detection unit is connected to the output voltage detection pin, the second The terminal is connected to the first terminal of the output voltage feedback loop operational transconductance amplifier, the third terminal is connected to the second terminal of the output voltage feedback loop operational transconductance amplifier and grounded, and the third terminal of the output voltage feedback loop operational transconductance amplifier is connected to the ground. terminal connected to The first terminal of the output voltage feedback loop compensation circuit and the first terminal of the output voltage feedback loop optocoupler drive circuit, the second terminal of the output voltage feedback loop compensation circuit is grounded, and the first terminal of the output voltage feedback loop optocoupler drive circuit is grounded. The second terminal is grounded, and the third terminal is connected to the optocoupler drive pin.

The off-line switching power supply circuit according to the embodiment of the present invention includes the above-mentioned feedback control chip for the off-line switching power supply circuit.

According to the off-line switching power supply circuit and the feedback control chip of the embodiment of the present invention, since a complete feedback loop is integrated inside the feedback control chip, the number of pins of the feedback control chip and the number of peripheral devices can be reduced, thereby improving system integration It saves system components and is conducive to realizing the miniaturization of the system.

100: Offline switching power supply circuit

102: Feedback control chip

200: Offline switching power supply circuit

202: Feedback control chip

202-1: Feedback control chip

202-2: Feedback control chip

202-3: Feedback control chip

2022: UVLO/LDO discharge module

2024: Digital Control Module

2026: Protocol Communication Module

2028: Output voltage and current protection control module

2030: Output voltage discharge control module

2032-1: Output voltage and output current feedback loop control module

2032-2: Output voltage feedback loop control module

2032-3: Output current feedback loop control module

2034: Load switch driver module

502: Output voltage detection unit

504: Output Voltage Feedback Loop Operational Transconductance Amplifier

506: Output voltage feedback loop compensation circuit

508: Output voltage feedback loop optocoupler drive circuit

510: Output voltage feedback loop optocoupler driver isolation diode

512: Output current sampling and amplification unit

514: Output Current Feedback Loop Operational Transconductance Amplifier

516: Output current feedback loop compensation circuit

518: Output current feedback loop optocoupler drive circuit

520: Output current feedback loop optocoupler driver isolation diode

522: output voltage discharge unit

524: Output wire voltage drop compensation unit

C1, C2, C3, C4, C20, C30: Capacitors

Co: output capacitance

DN/CC2: Protocol communication port pin

DP/CC1: Protocol communication port pin

Gate: Load switch drive pin

GND: chip reference ground pin

GPIO: input and output pins

IFB: Current Feedback Pin

Io_discharge: current source

ISN: Current Sense Negative Pin

ISP: Current Sense Positive Pin

K: scale parameter

OPTO: Optocoupler drive pin

R1, R2, R20, Rd: resistance

Ro: load

Ropto: Resistor

Rs: output current sampling resistor

VFB: Voltage Feedback Pin

Vo: output voltage detection pin

Vref_cv: Internal voltage reference

Vref_cc: Internal current reference

The present creation can be better understood from the following description of the specific embodiments of the present creation in conjunction with the drawings, wherein:

FIG. 1 shows a schematic structural diagram of a traditional off-line switching power supply circuit;

FIG. 2 shows an exemplary structural schematic diagram of an off-line switching power supply circuit according to an embodiment of the present invention;

FIG. 3 shows an example pinout diagram of a feedback control chip according to an embodiment of the present invention;

4A to 4C show exemplary structural schematic diagrams of a feedback control chip according to an embodiment of the present invention;

5A to 5C are schematic structural diagrams showing exemplary structures of a feedback loop control module in a feedback control chip according to an embodiment of the present invention;

FIG. 6 shows an example circuit implementation of the output voltage discharge unit shown in FIG. 5A;

FIG. 7 shows an example circuit implementation of the output wire voltage drop compensation unit shown in FIG. 5A .

Features and exemplary embodiments of various aspects of the present invention are described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the 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 creation by illustrating an example of the present creation. This creation is by no means limited to any specific configuration set forth below, but covers any modification, substitution and improvement of elements and components without departing from the spirit of this creation. In the drawings and the following description, well-known structures and techniques are not shown in order to avoid obscure the present invention cause unnecessary blur. In addition, it should be noted that the term "A and B are connected" used herein may mean "A and B are directly connected" or "A and B are indirectly connected via one or more other elements".

FIG. 1 shows a schematic structural diagram of a conventional off-line switching power supply circuit 100 . As shown in FIG. 1 , in order to meet the requirements of an off-line switching power supply circuit 100 such as a universal charger for adjustable output voltage and adjustable output current, the feedback control chip 102 needs at least 10 pins. If the miniaturization of the feedback control chip 102 is to be maintained, more expensive packages such as SSOP10/QFN16 must be used. At the same time, there are many feedback loop compensation devices (for example, capacitors C1-C4 and resistors R1-R2, etc.) around the feedback control chip 102, which makes the system reliability of the off-line switching power supply circuit 100 poor, the cost is high, and it is difficult to achieve a small size change.

In view of the problems existing in the traditional offline switching power supply circuit and its feedback control chip, an offline switching power supply circuit and its feedback control chip according to the embodiments of the present invention are proposed.

FIG. 2 shows a schematic structural diagram of an example of an offline switching power supply circuit 200 according to an embodiment of the present invention. 1 and 2, it can be seen that in the off-line switching power supply circuit 200, the feedback loop compensation device is integrated into the feedback control chip 202. Compared with the feedback control chip 102, the feedback control chip 202 has less voltage feedback pin VFB. And the current feedback pin IFB, there are only 8 basic function pins, which can be used in cheap packages such as the most commonly used SOP8.

In addition, since the feedback control chip 202 is integrated with a complete feedback loop, one or more functions related to the feedback loop can be additionally added inside the feedback control chip 202, for example, the output voltage feedback control function, the output current feedback control function , Output wire voltage drop compensation function, output voltage dynamic enhancement function, optocoupler drive maximum current clamp function, chip soft start function, output voltage/current soft switching function, output capacitor discharge function when output voltage is switched, etc. At the same time, the feedback control chip 202 can additionally add one or more protection functions of the secondary output, for example, an Over Voltage Protection (OVP) function, an Under Voltage Protection (UVP) function, and an overcurrent protection function. (Overcurrent Protection, OCP) function, overload protection (Overload Protection, OLP) function and so on.

FIG. 3 shows an example pinout diagram of the feedback control die 202 according to an embodiment of the present invention. 2 and 3, it can be seen that the feedback control chip 202 includes the following pins:

Current detection positive pin ISP, connected to the output current sampling resistor (for example, Rs), Used to realize output current feedback control and OCP control.

The current detection negative pin ISN is connected to the output current sampling resistor (for example, Rs) for output current feedback control and OCP control.

The output voltage detection pin Vo is connected to the positive pole of the output capacitor (for example, Co), and is used to realize the output voltage feedback control and the discharge control during the output voltage switching process.

The optocoupler drive pin OPTO is connected to the cathode of the optocoupler diode, and is used to control the magnitude of the current flowing through the optocoupler, thereby realizing the control of the system loop. Specifically, the magnitude of the current flowing through the optocoupler is controlled by the optocoupler driving circuit built in the feedback control chip 202 . The anode of the optocoupler can be connected to the output voltage via a resistor (eg, Ropto) or directly to the output voltage.

The chip reference ground pin, GND, is connected to the cathode of the output capacitor (eg, Co) or the negative voltage terminal of the load (eg, Ro).

The load switch driving pin Gate is connected to the gate of the load switch, and is used to control the turn-on and turn-off of the load switch. In FIG. 2, an N-type metal oxide semiconductor (N-type metal oxide semiconductor, NMOS) transistor is used as the load switch, and the load switch is set at the positive terminal of the system output. In fact, the load switch is not limited to an NMOS transistor, and a P-type metal oxide semiconductor (P-type metal oxide semiconductor, PMOS) transistor or the like can also be used. In addition, the load switch can also be set at the negative terminal of the system output. In some applications, the output voltage is directly connected to the load without going through the load switch, and the load switch drive pin Gate can be left floating, grounded via a resistor, or directly grounded.

Protocol communication port pins DP/CC1 and DN/CC2 can support Quick Charge (QC) protocol or Power Delivery (PD) protocol through internal switching. However, it is not limited to QC or PD protocol, the protocol communication port pins can also support other communication protocols. In practical applications, the number of protocol communication port pins can be increased to meet the communication protocol requirements of the system.

It should be noted that the feedback control chip 202 is not limited to include 8 pins, but may include fewer or more pins according to actual system applications. For example, the feedback control die 202 may also include one or more general-purpose input and output pins, GPIO.

In some embodiments, the feedback control chip 202 may be used in output voltage feedback and output current feedback systems. FIG. 4A shows a schematic structural diagram of an exemplary structure of a feedback control chip 202 - 1 applied in an output voltage feedback or output current feedback system according to an embodiment of the present invention. As shown in FIG. 4A , the feedback control chip 202-1 includes undervoltage lockout and low dropout (Undervoltage Lockout, UVLO/Low Dropout, LDO) discharge module 2022, digital control module 2024 (eg, micro-control unit), protocol communication module 2026, output voltage and current protection control module 2028, output voltage discharge control module 2030, output voltage and the output current feedback loop control module 2032-1, and the load switch drive module 2034, wherein: one end of the UVLO/LDO discharge module 2022 is connected to the output voltage detection pin Vo, and the other end is connected to the digital control module 2024 , the first and second ends of the protocol communication module 2026 are respectively connected to the protocol communication port pins DP/CC1 and DN/CC2, the third end is connected to the digital control module 2024, and the output voltage and current protection control module 2028 is connected to The digital control module 2024, the output voltage discharge control module 2030 is connected to the digital control module 2024, and the output voltage and output current feedback loop control module 2032-1 is connected to the current detection positive pin ISP and the current detection negative pin ISN , and the optocoupler drive pin OPTO and connected to the digital control module 2024 , one end of the load switch drive module 2034 is connected to the load switch drive pin Gate, and the other end is connected to the digital control module 2024 .

In some embodiments, the feedback control die 202 may also be used in an output voltage-only feedback system. FIG. 4B shows a schematic structural diagram of an example of a feedback control chip 202 - 2 applied in an output voltage feedback system according to an embodiment of the present invention. The difference between the feedback control chip 202-2 and the feedback control chip 202-1 is that it includes an output voltage feedback loop control module 2032-2 instead of the output voltage and output current feedback loop control module 2032-1. The other aspects of the feedback control chip 202-2 are the same as those of the feedback control chip 202-1, and are not repeated here.

In some embodiments, the feedback control chip 202 may also be used in an output current feedback system. FIG. 4C shows an exemplary structural schematic diagram of the feedback control chip 202 - 3 applied in the output current feedback system according to an embodiment of the present invention. The difference between the feedback control chip 202-3 and the feedback control chip 202-1 is that the output current feedback loop control module 2032-3 is included instead of the output voltage and output current feedback loop control module 2032-1. The other aspects of the feedback control chip 202-3 are the same as those of the feedback control chip 202-1, and are not repeated here.

FIG. 5A shows an exemplary structural schematic diagram of the output voltage and output current feedback loop control module 2032-1 according to an embodiment of the present invention. As shown in FIG. 5A , the output voltage and output current feedback loop control module 2032-1 includes an output voltage detection unit 502, an output voltage feedback loop operational transconductance amplifier 504, an output voltage feedback loop compensation circuit 506, an output voltage feedback loop Loop optocoupler drive circuit 508, output voltage feedback loop optocoupler drive isolation diode 510, output current sampling and amplifying unit 512, output current feedback loop operational transconductance amplifier 514, output current feedback loop compensation circuit 516, The output current feedback loop optocoupler driving circuit 518 and the output current feedback loop optocoupler drive isolation diode 520 .

As shown in FIG. 5A , the first terminal of the output voltage detection unit 502 is connected to the output voltage detection pin Vo, the second terminal is connected to the first terminal of the output voltage feedback loop operational transconductance amplifier 504, and the third terminal is connected to the output The second terminal of the voltage feedback loop operational transconductance amplifier 504 is connected to ground; the third terminal of the output voltage feedback loop operational transconductance amplifier 504 is connected to the first terminal of the output voltage feedback loop compensation circuit 506 and the output voltage feedback loop The first terminal of the optocoupler driving circuit 508; the second terminal of the output voltage feedback loop compensation circuit 506 is grounded; the second terminal of the output voltage feedback loop optocoupler driving circuit 508 is grounded, and the third terminal is connected to the output voltage feedback loop The first terminal of the optocoupler driving isolation diode 510; the second terminal of the output voltage feedback loop optocoupler driving isolation diode 510 is connected to the optocoupler driving pin OPTO.

As shown in FIG. 5A , the first terminal of the output current sampling and amplification unit 512 is connected to the output current detection positive pin ISP, the second terminal is connected to the output current detection negative pin ISN, and the third terminal is connected to the output current feedback loop The first terminal of the operational transconductance amplifier 514; the second terminal of the output current feedback loop operational transconductance amplifier 514 is grounded, the third terminal is connected to the first terminal of the output current feedback loop compensation circuit 516 and the output current feedback loop light The first terminal of the coupling driving circuit 518; the second terminal of the output current feedback loop compensation circuit 516 is grounded; the second terminal of the output current feedback loop optocoupler driving circuit 518 is grounded, and the third terminal is connected to the output current feedback loop light The first terminal of the coupling and driving isolation diode 520; the second terminal of the output current feedback loop opto-coupler driving the isolation diode 520 is connected to the opto-coupler driving pin OPTO.

As shown in FIG. 5A , in some embodiments, the feedback loop control module 2032-1 further includes an output voltage discharge unit 522, wherein the first terminal of the output voltage discharge unit 522 is connected to the output voltage detection pin Vo, the first terminal of the output voltage discharge unit 522 Both ends are grounded.

As shown in FIG. 5A, in some embodiments, the feedback loop control module 2032-1 further includes an output wire voltage drop compensation unit 524, wherein the first terminal of the output wire voltage drop compensation unit 524 is connected to the output voltage detection unit The second terminal, the second terminal of 502 is connected to the third terminal of the output voltage detection unit 502 .

FIG. 5B shows an exemplary structural schematic diagram of the output voltage feedback loop control module 2032 - 2 according to an embodiment of the present invention. As shown in FIG. 5B, the output voltage feedback loop control module 2032-2 It includes an output voltage detection unit 502, an output voltage feedback loop operational transconductance amplifier 504, an output voltage feedback loop compensation circuit 506, and an output voltage feedback loop optocoupler driving circuit 508, and in some embodiments may further include an output voltage Discharge unit 522 and output wire voltage drop compensation unit 524 . In the output voltage feedback loop control module 2032-2, the third terminal of the output voltage feedback loop optocoupler driving circuit 508 does not need to be connected to the optocoupler driving pin via the output voltage feedback loop optocoupler driving isolation diode 510 OPTO, other connection relationships are the same as the corresponding connection relationships in the output voltage and output current feedback loop control module 2032-1, and are not repeated here.

FIG. 5C shows an exemplary structural schematic diagram of the output current feedback loop control module 2032 - 3 according to an embodiment of the present invention. As shown in FIG. 5C , the output current feedback loop control module 2032-3 includes an output current sampling and amplifying unit 512, an output current feedback loop operational transconductance amplifier 514, an output current feedback loop compensation circuit 516, and an output current feedback loop Loop optocoupler drive line 518 . In the output current feedback loop control module 2032-3, the third terminal of the output current feedback loop optocoupler driving circuit 518 does not need to be connected to the optocoupler driving pin via the output current feedback loop optocoupler driving isolation diode 520 OPTO, other connection relationships are the same as the corresponding connection relationships in the output voltage and output current feedback loop control module 2032-1, and are not repeated here.

Below, the specific functions of each functional unit shown in FIG. 5A to FIG. 5C are introduced:

The output voltage detection unit 502 is used for dividing and sampling the output voltage of the system, and reducing the output voltage to a reasonable voltage range for use by the subsequent functional units. For example, in the output voltage detection unit 502, resistors R1 and Rd are used to divide the output voltage, and the output voltage is reduced to a reasonable voltage range for use by subsequent functional units; the capacitor C1 is a loop compensation capacitor; , the capacitor C1 can be connected in parallel with the resistor R1 or with the resistor Rd; at the same time, the capacitor C1 can also be replaced by a resistor-capacitor combination. Here, the dynamic enhancement compensation function means that when it is detected that the output voltage exceeds the set output range, the dynamic enhancement circuit is activated, so that the dynamic enhancement circuit sinks/sources current to the output of the output voltage feedback loop compensation circuit 508, and pulls the output voltage back to the set voltage range. The output voltage detection unit 502 is mainly related to the output voltage feedback loop function, the dynamic enhancement compensation function, and the OVP/UVP protection function.

The output voltage feedback loop operational transconductance amplifier 504 is used to compare the output voltage sampled by the output voltage detection module 502 with the internal voltage reference Vref_cv to generate an error current output. Here, the internal voltage reference Vref_cv can be a fixed value or can be set by a microcontroller (Microcontroller, MCU) configuration variable value. When the system starts up or when the output voltage is switched, the soft-start and soft-switching of the output voltage buck-boost can be realized by means of Vref_cv soft-up and soft-down. In order to improve the system dynamic performance, the output voltage of the output voltage feedback loop operational transconductance amplifier 504 needs to be within a certain range, for example, [Vgm_min, Vgm_max]. When the output voltage detection unit 502 detects that the output voltage exceeds the set threshold range, the dynamic enhancement circuit is activated to sink/source the output of the output voltage feedback loop operational transconductance amplifier 504 to pull the output voltage back to the set voltage range .

The output voltage feedback loop compensation circuit 506 is used to make the system have reasonable time domain performance and frequency domain performance by selecting reasonable resistors and capacitors. For example, the output voltage feedback loop compensation circuit 506 may include a resistor R2 and a capacitor C2 connected between the output terminal of the output voltage feedback loop operational transconductance amplifier 504 and the reference ground, and a resistor R2 and a capacitor C2 connected between the output voltage feedback loop operational transconductor The capacitor C3 between the output end of the amplifier 504 and the reference ground, wherein the resistor R2 and the capacitor C2 are connected in series, and reasonable time-domain performance and frequency-domain performance can be obtained by setting reasonable resistor and capacitor values. It should be noted that this creation does not limit the output voltage feedback loop compensation circuit, and any other suitable circuits that can realize the compensation function are within the scope of this creation. Usually, the open-loop phase margin of a stable system may need to be, for example, more than 45 degrees, and the gain margin may need to be, for example, more than 10-12 dB.

The output voltage feedback loop optocoupler driving circuit 508 is used to drive the optocoupler in a pull-down manner, so as to transmit the secondary control to the primary control chip through the optocoupler. The circuits shown in FIG. 5A and FIG. 5B are only schematic diagrams, and the connection methods include the circuits shown in the figures, and also include directly connecting the output voltage of the output voltage feedback loop compensation circuit 506 to a metal oxide semiconductor (metal oxide semiconductor, MOS) method, or other connection methods.

The output voltage feedback loop optocoupler-driven isolation diode 510 is used to isolate the output voltage feedback loop and the output current feedback loop to prevent the two loop systems from interfering with each other in different modes.

The output current sampling and amplifying unit 512 is used for sampling the voltage on the sampling resistor of the output current, and amplifying the sampled voltage to obtain an optimized voltage range for use by subsequent functional units. The output current sampling and amplifying unit 512 is mainly related to the output current feedback loop back-to-body function and the OCP protection function.

The output current feedback loop op-amp 514 is used to compare the output voltage of the output current sampling and amplifying unit 512 with the internal current reference Vref_cc to generate an error current output. The internal current reference Vref_cc can be a fixed value or a variable value configured by the MCU. in the output power When the current is switched, the soft switching of the output current can be realized by means of the soft rise and soft fall of Vref_cc.

The output current feedback loop compensation circuit 516 is used to make the system have reasonable time-domain performance and frequency-domain performance by selecting reasonable resistors and capacitors. For example, the output current feedback loop compensation circuit 516 may include a resistor R20 and a capacitor C20 connected between the output terminal of the output current feedback loop operational transconductance amplifier 514 and the reference ground, and a resistor R20 and a capacitor C20 connected between the output current feedback loop operational transconductor The capacitor C30 between the output end of the amplifier 514 and the reference ground, wherein the resistor R20 and the capacitor C20 are connected in series, and reasonable time-domain performance and frequency-domain performance can be obtained by setting reasonable resistor and capacitor values. It should be noted that this creation does not limit the output current feedback loop compensation circuit, and any other suitable circuits that can realize the compensation function are within the scope of this creation. In a stable system, the open-loop phase margin needs to be, for example, 45 degrees or more, and the gain margin needs to be, for example, 10 to 12 dB or more.

The output current feedback loop optocoupler driving circuit 518 is used to drive the optocoupler in a pull-down manner, and transmit the secondary control to the primary control chip through the optocoupler. The circuits shown in FIG. 5A and FIG. 5C are only examples, and the connection methods include the circuits shown in the figures, the method of directly connecting the output voltage of the output current feedback loop compensation circuit 516 to the MOS, or other connection methods.

The output current feedback loop optocoupler drives the isolation diode 520 to isolate the output voltage feedback loop and the output current feedback loop to prevent the two loop systems from interfering with each other in different modes.

The output voltage discharge unit 522 is mainly used to turn on when the output voltage is switched by the internal voltage reference Vref_cv under no-light load conditions. The output voltage discharge unit 522 acts as a dummy load of the system, and can quickly discharge the output voltage to a set voltage when the output voltage is reduced to meet the system voltage reduction time and performance specifications, and can suppress the output voltage by discharging when the output voltage is boosted overshoot, so that the output voltage returns to the set voltage as soon as possible. In FIGS. 5A and 5B , the output voltage discharge unit 522 is implemented by a constant current source (eg, current source Io_discharge), but replacing the constant current source with a resistor (eg, Rdis) can also implement the above functions. FIG. 6 illustrates an example circuit implementation of an output voltage discharge cell according to an embodiment of the present invention.

The output wire voltage drop compensation unit 524 is used to multiply the output voltage of the output current sampling and amplifying unit 512 (which contains information related to the output current) by an appropriate scaling parameter K (eg, K*(V_sip-Visn)) , using a voltage controlled current source (Voltage Controlled Current Source, VCCS) to provide a compensation current for the output wire, so that the compensation current flows into the sampling point of the output voltage detection unit 502, that is, the common terminal of the resistor R1 and the resistor Rd . by choosing Appropriate proportional parameter K can realize the compensation for the line terminal voltage drop caused by the output wire, so that the line terminal voltage is always maintained at the set value in the full load range. FIG. 7 shows an example circuit implementation of the output wire voltage drop compensation unit 524 according to an embodiment of the present invention. As shown in Figure 7, a voltage source proportional to the output current (for example, kk*(V_isp-V_isn)*Gain) is superimposed on the internal voltage reference Vref_cv to compensate for the line-end voltage drop caused by the output wire. The parameter K can keep the line terminal voltage at the set value in the full load range.

To sum up, this creation provides a feedback control chip for an offline switching power supply circuit. The feedback control chip can amplify the error between the output voltage or current and the set reference value through an Operational Transconductance Amplifier (OTA). , and then transmit the feedback signal to the primary control chip through the optocoupler drive line. In addition, the feedback control chip can simultaneously integrate one or more of the following functions: output voltage feedback control function, output current feedback control function, output wire voltage drop compensation function, output voltage dynamic enhancement function, output voltage/current soft switching function, It discharges the output capacitor during buck-boost. This highly integrated feature of the feedback control chip can meet the application of multiple output voltages such as PD/QC.

This creation can be realized in other specific forms without departing from its spirit and essential characteristics. The present embodiments are to be considered in all respects as illustrative and not restrictive, and the scope of the present invention is defined by the appended claims rather than the foregoing description, and within the meaning and range of equivalents of the claims. All changes are included in the scope of this creation.

202-2: Feedback control chip

2022: UVLO/LDO discharge module

2024: Digital Control Module

2026: Protocol Communication Module

2028: Output voltage and current protection control module

2030: Output voltage discharge control module

2032-2: Output voltage feedback loop control module

2034: Load switch driver module

DN/CC2: Protocol communication port pin

DP/CC1: Protocol communication port pin

Gate: Load switch drive pin

GND: chip reference ground pin

ISN: Current Sense Negative Pin

ISP: Current Sense Positive Pin

OPTO: Optocoupler drive pin

Vo: output voltage detection pin

Claims (13)

A feedback control chip for an off-line switching power supply circuit, characterized in that it includes an output voltage detection pin, an optocoupler driving pin, and a feedback loop control module, wherein: the feedback loop control module includes an output a voltage detection unit, an output voltage feedback loop operational transconductance amplifier, an output voltage feedback loop compensation circuit, and an output voltage feedback loop optocoupler driving circuit, the first terminal of the output voltage detection unit is connected to the output voltage detection The pin and the second terminal are connected to the first terminal of the output voltage feedback loop operational transconductance amplifier, and the third terminal is connected to the second terminal of the output voltage feedback loop operational transconductance amplifier and grounded, and the output The third terminal of the voltage feedback loop operational transconductance amplifier is connected to the first terminal of the output voltage feedback loop compensation circuit and the first terminal of the output voltage feedback loop optocoupler driving circuit, the output voltage feedback loop The second terminal of the circuit compensation line is grounded, the second terminal of the output voltage feedback loop optocoupler driving line is grounded, and the third terminal is connected to the optocoupler driving pin. The feedback control chip according to claim 1, wherein the feedback loop control module further comprises an output voltage discharge unit, wherein the first terminal of the output voltage discharge unit is connected to the output voltage detection pin, The second terminal is grounded. The feedback control chip of claim 1, wherein the feedback loop control module further comprises an output wire voltage drop compensation unit, wherein a first terminal of the output wire voltage drop compensation unit is connected to the output voltage The second terminal, the second terminal of the detection unit is connected to the third terminal of the output voltage detection unit. The feedback control chip according to claim 1, wherein the feedback loop control module further comprises an output voltage feedback loop optocoupler driving isolation diode, wherein the output voltage feedback loop optocoupler driving isolation diode The pole body is connected between the optocoupler drive pin and the third terminal of the output voltage feedback loop optocoupler drive line. The feedback control chip according to claim 1, further comprising an output current detection positive pin and an output current detection negative pin, wherein: the feedback loop control module further comprises an output current sampling and amplifying unit, an output current detection Feedback loop operational transconductance amplifier, output current feedback loop compensation circuit, and output current feedback loop optocoupler drive circuit, The first terminal of the output current sampling and amplifying unit is connected to the output current detection positive pin, the second terminal is connected to the output current detection negative pin, and the third terminal is connected to the output current feedback loop operation the first terminal of the transconductance amplifier, the second terminal of the output current feedback loop operational transconductance amplifier is grounded, and the third terminal is connected to the first terminal of the output current feedback loop compensation circuit and the output current feedback loop The first terminal of the optocoupler drive circuit is grounded, the second terminal of the output current feedback loop compensation circuit is grounded, the second terminal of the output current feedback loop optocoupler drive circuit is grounded, and the third terminal is connected to the optical coupled drive pin. The feedback control chip according to claim 5, wherein the feedback loop control module further comprises an output current feedback loop optocoupler driving isolation diode, wherein the output current feedback loop optocoupler driving isolation diode The polar body is connected between the optocoupler drive pin and the third terminal of the output current feedback loop optocoupler drive line. The feedback control chip of claim 1, further comprising a digital control module, wherein the digital control module is connected to the feedback loop control module. The feedback control chip according to claim 7, further comprising an undervoltage lockout and low dropout discharge module, wherein one end of the undervoltage lockout and low dropout discharge module is connected to the output voltage detection pin, The other end is connected to the digital control module. The feedback control chip according to claim 7, further comprising a load switch drive pin and a load switch drive module, wherein one end of the load switch drive module is connected to the load switch drive pin and the other end connected to the digital control module. The feedback control chip according to claim 7, further comprising a protocol communication port pin and a protocol communication module, wherein one end of the protocol communication module is connected to the protocol communication port pin and the other end connected to the digital control module. The feedback control chip according to claim 7, further comprising an output voltage discharge control module connected to the digital control module. The feedback control chip according to claim 7, further comprising an output voltage and current protection control module connected to the digital control module. An off-line switching power supply circuit, comprising any one of claims 1 to 12 feedback control chip.

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