Switching power supply circuit and control chip used for switching power supply

Abstract

The present application relates to a switching power supply circuit and a control chip applied to the switching power supply, including a mode recognition module and a feedback voltage detection module, wherein the mode recognition module includes a first input terminal VS and a second input terminal VCC. The mode recognition module identifies whether the switching power supply circuit is a flyback switching power supply circuit or a buck switching power supply circuit according to the access voltages of the first input terminal VS and the second input terminal VCC, and outputs the corresponding access voltage as a feedback signal to the feedback voltage detection module; the feedback voltage detection module is used to detect the voltage signal output by the mode recognition module, and output the detection result to the PWM module, so that the PWM module outputs a pulse width modulated power switch signal according to the detection result. This can solve the problem that the existing switching power supply circuit control chip has poor versatility, resulting in a complex design process, low efficiency and high cost.

Description

Technical Field

[0001] The present application relates to a switching power supply circuit and a control chip applied to the switching power supply, belonging to the technical field of switching power supplies. Background Art

[0002] As the functions of electronic devices become more and more complex, the requirements for switching power supplies are getting higher and higher, and switching power supply technology has achieved unprecedented development. In order to manage a wider range of loads, lower output voltages, and multiple power supplies simultaneously, more and more electronic products or household appliances are using Buck power supplies and Flyback power supplies.

[0003] Although Buck power supplies and Flyback power supplies have significant differences in structure, their control principles are basically the same. Therefore, if a power chip can be used for switching power supplies of two different structures at the same time, the power control chip can be made universal, avoiding waste of resources, improving power design efficiency, and reducing design costs. Summary of the invention

[0004] The present application provides a switching power supply circuit and a control chip applied to the switching power supply circuit, which can solve the problem that the existing switching power supply circuit control chip has poor versatility, resulting in a complex design process, low efficiency and high cost.

[0005] This application provides the following technical solutions:

[0006] In a first aspect, a control chip for a switching power supply is provided, comprising a feedback voltage detection module and a PWM module, wherein the feedback voltage detection module is used to detect a voltage signal at an output end of a power supply, the output end of the feedback voltage detection module is connected to the PWM module, and the PWM module is used to output a power switch signal after pulse width modulation; the control chip further comprises a pattern recognition module, the pattern recognition module comprises a first input end VS and a second input end VCC, and a feedback signal output end of the pattern recognition module is connected to an input end of the feedback voltage detection module;

[0007] When the control chip is connected to the flyback switching power supply circuit, the first input terminal VS is connected to the power supply output terminal, and the mode recognition module connects the first input terminal VS with the second input terminal VCC according to the input signals of the first input terminal VS and the second input terminal VCC to power the control chip, and outputs the voltage signal connected to the first input terminal VS as a feedback signal to the feedback voltage detection module;

[0008] When the control chip is connected to a step-down switching power supply circuit, the first input terminal VS is suspended, the second input terminal VCC is connected to the power output terminal, and the second input terminal VCC serves as the power supply terminal of the control chip. The mode recognition module outputs the voltage signal connected to the second input terminal VCC as a feedback signal to the feedback voltage detection module based on the input signals of the first input terminal VS and the second input terminal VCC.

[0009] Further, according to the control chip described in the first aspect of the present application, the pattern recognition module includes a first control circuit and a second control circuit, and a first switch, a second switch and a third switch;

[0010] The first switch is connected between the first input terminal and the second input terminal;

[0011] The second switch is connected between the first input terminal and the feedback signal output terminal;

[0012] The third switch is connected between the second input terminal and the feedback signal output terminal;

[0013] The input end of the first control circuit is connected to the first input end and the second input end respectively, and the output end of the first control circuit is connected to the control end of the first switch;

[0014] The input end of the second control circuit is respectively connected to the first input end and the reference voltage signal, and the output end of the second control circuit outputs two control signals, one of which is connected to the control end of the second switch, and the other is connected to the control end of the third switch;

[0015] When the control chip is connected to the flyback switching power supply circuit, the first control circuit is used to control the first switch to be turned on, the second control circuit is used to control the second switch to be turned on, and the third switch to be turned off;

[0016] When the control chip is connected to a step-down switching power supply circuit, the first control circuit is used to control the first switch to be turned off, the second control circuit is used to control the second switch to be turned off, and the third switch to be turned on.

[0017] Further, according to the control chip described in the first aspect of the present application, the first control circuit includes a first comparator, a non-inverting input terminal of the first comparator is connected to the first input terminal, an inverting input terminal of the first comparator is connected to the second input terminal, and an output terminal of the first comparator is connected to the control terminal of the first switch;

[0018] The second control circuit includes a second comparator and a third inverter, the non-inverting input of the second comparator is connected to the first input, the inverting input of the second comparator is connected to a reference voltage, the output of the second comparator is connected to the control end of the second switch, and the output of the second comparator is connected to the control end of the third switch through the third inverter.

[0019] Further, according to the control chip described in the first aspect of the present application, the first control circuit further includes a first memory circuit, and the second control circuit further includes a second memory circuit, a first AND gate, and a second AND gate;

[0020] The first memory circuit is connected between the first comparator and the first switch, the output signal of the first comparator and the initial signal when the switch power supply is started are respectively connected to the two input ends of the first memory circuit, and the output end of the first memory circuit is connected to the control end of the first switch;

[0021] The output signal of the second comparator and the initial signal when the switch power supply is started are respectively connected to two input terminals of the second memory circuit, and the output terminal of the second memory circuit outputs two control signals, one of which is connected to one input terminal of the first AND gate, and the other is connected to one input terminal of the second AND gate through the third inverter;

[0022] The other input ends of the first AND gate and the second AND gate are both connected to the initial signal when the switching power supply is started, and the output end of the first AND gate is connected to the control end of the second switch, and the output end of the second AND gate is connected to the control end of the third switch.

[0023] Further, according to the control chip described in the first aspect of the present application, the first memory circuit includes a first RS trigger and a first inverter, and the second memory circuit includes a second RS trigger and a second inverter;

[0024] The set end of the first RS trigger is connected to the output signal of the first comparator, the initial signal when the switching power supply is started is connected to the reset end of the first RS trigger through the first inverter, and the output end of the first RS trigger is connected to the control end of the first switch;

[0025] The set end of the second RS trigger is connected to the output signal of the second comparator, the initial signal when the switching power supply is started is connected to the reset end of the second RS trigger through the second inverter, and the output end of the second RS trigger is connected to an input end of the first AND gate, and is connected to an input end of the second AND gate through the third inverter.

[0026] Further, according to the control chip described in the first aspect of the present application, when the control chip is connected to a flyback switching power supply circuit, the second input terminal VCC is connected to the ground terminal of the control chip through the first capacitor; when the control chip is connected to a step-down switching power supply circuit, the second input terminal VCC is connected to the ground terminal of the control chip through the second capacitor.

[0027] Further, according to the control chip described in the first aspect of the present application, the control chip includes a high-voltage starting circuit, the input end of the high-voltage starting circuit is connected to the power input end, the output end of the high-voltage starting circuit is connected to the second input end VCC, and the high-voltage starting circuit is used to charge the first capacitor or the second capacitor of the second input end VCC when the system is powered on, so that the control chip starts normally.

[0028] Further, according to the control chip described in the first aspect of the present application, the control chip also includes an oscillation circuit, the input end of the oscillation circuit is connected to the output end of the feedback voltage detection module, the output end of the oscillation circuit is connected to the PWM module, the oscillation circuit is used to generate an operating frequency of the switching power supply circuit, and the PWM module adjusts the frequency of the power switch signal according to the operating frequency.

[0029] Further, according to the control chip described in the first aspect of the present application, the control chip includes a protection module, the protection module is connected to the PWM module, and the protection module is used to send a signal to the PWM module when a system abnormality is detected, so as to turn off the power switch tube through the PWM module.

[0030] In a second aspect, a switching power supply circuit is provided, including a Buck power supply or a Flyback power supply, the switching power supply circuit also including the control chip described in the first aspect, the control chip is connected to the Buck power supply peripheral circuit to form a step-down switching power supply circuit; the control chip is connected to the Flyback power supply peripheral circuit to form a flyback switching power supply circuit.

[0031] The beneficial effect of the present application is that the control chip applied to the switching power supply circuit of the present application is provided with a pattern recognition module, which can distinguish whether it is a step-down switching power supply circuit or a flyback switching power supply circuit, and according to different switching power supply circuits, the access voltage of the corresponding first input terminal or the second input terminal is output as a feedback signal, so that the control chip can be applied to both the flyback switching power supply circuit and the step-down switching power supply circuit, thereby improving the versatility and utilization rate of the control chip and reducing the manufacturing cost.

[0032] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present application in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a structural block diagram of a switching power supply provided by an embodiment of the present application;

[0034] Figure 2 is a structural principle diagram of a control chip provided by an embodiment of the present application;

[0035] Figure 3 is a circuit structure schematic diagram of a pattern recognition module provided by an embodiment of the present application;

[0036] Figure 4 is a circuit structure schematic diagram of a pattern recognition module provided in another embodiment of the present application;

[0037] Figure 5 This is a circuit diagram of a control chip provided in an embodiment of the present application applied to a flyback switching power supply;

[0038] Figure 6 This is a circuit diagram of a control chip provided in an embodiment of the present application applied to a step-down switching power supply;

[0039] Figure 7 This is a schematic diagram of the packaging of the integrated design of the power switch tube and the control chip provided by an embodiment of the present application;

[0040] Figure 8 It is a packaging schematic diagram of an integrated design of a power switch tube and a control chip provided in another embodiment of the present application. DETAILED DESCRIPTION

[0041] The specific implementation methods of the present application are further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application but are not intended to limit the scope of the present application.

[0042] A switching power supply, also known as a switching regulated power supply, is a new type of regulated power supply circuit relative to a linear regulated power supply. It stabilizes the output voltage by real-time monitoring of the output voltage and dynamically controlling the time ratio of the switch on and off.

[0043] The switching power supply described in the embodiment of the present application can adopt a Buck power supply topology or a Flyback power supply topology, wherein the Buck power supply topology constitutes a step-down switching power supply, and the Flyback power supply topology constitutes a flyback switching power supply.

[0044] Figure 1 is a structural block diagram of a switching power supply provided by an embodiment of the present application, such as Figure 1 As shown, the switching power supply includes a Buck power supply or a Flyback power supply, and a corresponding control chip, wherein the control chip is connected to the power output terminal of the switching power supply to monitor the change of the output voltage of the switching power supply in real time. The driving signal output terminal of the control chip is connected to the control terminal of the power switch tube to control the conduction and cutoff of the power switch tube, thereby dynamically adjusting the pulse width or frequency of the power switch signal in a timely manner, and finally obtaining a stable output voltage.

[0045] Figure 2 FIG. 1 is a schematic diagram of a control chip used in a switching power supply according to an embodiment of the present application. Figure 2 As shown, the control chip includes:

[0046] Feedback voltage detection module FB: the input end of the feedback voltage detection module FB is connected to the power supply output voltage signal, and is used to process the connected power supply output voltage signal and output it to the PWM module.

[0047] The PWM (Pulse Width Modulation) module is used to receive the power supply output voltage signal output by the feedback voltage detection module FB, and provide a corresponding PWM switch signal according to the change of the power supply output voltage.

[0048] The driving module DRV is used to receive the PWM switch signal output by the PWM module, and convert the PWM switch signal into a drive signal and output it to the control end of the power switch tube, so as to dynamically adjust the ratio of the on-time and off-time of the power switch tube in a timely manner, thereby obtaining a stable output voltage. The power switch tube may not be integrated into the control chip, but may be used as a peripheral circuit device of the control chip.

[0049] Furthermore, the control chip of the embodiment of the present application further includes:

[0050] A current detection module CS, the input end of which is connected to the switch power supply circuit, and the output end of which is connected to the PWM module. The current detection module CS is used to detect the current of the switch power supply circuit and output the detection result to the PWM module, so that the PWM module adjusts the pulse width of the power switch signal according to the current signal and the voltage signal output by the feedback voltage detection module FB.

[0051] An oscillator circuit OSC, wherein the input end of the oscillator circuit is connected to a feedback voltage detection module FB, and the output end of the oscillator circuit OSC is connected to a PWM module. The oscillator circuit OSC is used to receive a power supply output voltage signal detected by the feedback voltage detection module FB, and generate an operating frequency of the switching power supply according to the power supply output voltage signal, and then output it to the PWM module, so that the PWM module adjusts the frequency of the power supply switching signal according to the operating frequency.

[0052] The high-voltage startup circuit HV is used to ensure that the control chip starts normally when the system where the switching power supply is located is powered on.

[0053] Optionally, the control chip of the embodiment of the present application is further provided with a protection module PRO, and the protection module PRO is used to shut down the power switch tube Q1 through the PWM module when a system abnormality is detected. The power switch tube Q1 is connected to the loop of the BUCK switching power supply or the Flyback switching power supply, and the power switch tube Q1 can be integrated inside the chip or externally placed, which is not limited in the present application.

[0054] Furthermore, the control chip of the embodiment of the present application further includes a mode recognition module DET, and the mode recognition module DET is used to identify whether the system where the control chip is located is a flyback switching power supply or a buck switching power supply.

[0055] Specifically, the mode recognition module DET is provided with a first input terminal VS and a second input terminal VCC, wherein when the control chip is connected to a flyback switching power supply circuit, the voltage of the power supply output terminal is connected through the first input terminal VS; when the control chip is connected to a buck switching power supply circuit, the voltage of the power supply output terminal is connected through the second input terminal VCC. The mode recognition module determines whether the system where the control chip is located is a flyback switching power supply or a buck switching power supply according to the input signals of the first input terminal VS and the second input terminal VCC, and the feedback signal output terminal of the mode recognition module is connected to the feedback voltage detection module FB.

[0056] At the same time, the second input terminal VCC is connected to the output terminal of the high-voltage startup circuit, and supplies power to the control chip when the switching power supply is powered on, ensuring that the control chip can start normally, and the second input terminal VCC serves as the working power supply of the control chip to supply power to the control chip, ensuring that the control chip can work normally.

[0057] Figure 3 A circuit structure schematic diagram of a pattern recognition module of an embodiment of the present application is given as follows: Figure 3 As shown, the pattern recognition module includes a first control circuit 1 and a second control circuit 2, as well as a first switch K1, a second switch K2 and a third switch K3.

[0058] The first control circuit 1 is used to control the first switch K1 to be turned on when the control chip is connected to a flyback switching power supply circuit, and to control the first switch K1 to be turned off when the control chip is connected to a buck switching power supply circuit.

[0059] The second control circuit 2 is used to control the second switch K2 to be turned on and the third switch K3 to be turned off when the control chip is connected to a flyback switching power supply circuit; when the control chip is connected to a step-down switching power supply circuit, the second switch K2 is turned off and the third switch K3 is turned on.

[0060] like Figure 3 In this embodiment, the first control circuit 1 includes a first comparator COM1, and the second control circuit 2 includes a second comparator COM2 and a third inverter INV3.

[0061] The pattern recognition module is provided with a feedback signal output terminal, a first input terminal VS and a second input terminal VCC, wherein the first input terminal VS is connected to the ground through a resistor RVS by default, and when the VS terminal is left floating, VS is at a low level by default, and the second input terminal VCC serves as a power supply terminal for the control chip.

[0062] The non-inverting input terminal of the first comparator COM1 is connected to the first input terminal VS, the inverting input terminal of the first comparator COM1 is connected to the second input terminal VCC, the output terminal of the first comparator COM1 is connected to the control terminal of the first switch K1, one end of the first switch K1 is connected to the first input terminal VS, and the other end is connected to the second input terminal VCC.

[0063] The non-inverting input terminal of the second comparator COM2 is connected to the first input terminal VS, the inverting input terminal of the second comparator COM2 is connected to the reference voltage VREF, the output terminal of the second comparator COM2 is connected to the control terminal of the second switch K2, one end of the second switch K2 is connected to the first input terminal VS, and the other end of the second switch K2 is connected to the feedback signal output terminal of the pattern recognition module DET.

[0064] The output end of the second comparator COM2 is also connected to the control end of the third switch K3 through the third inverter INV3. One end of the third switch K3 is connected to the feedback signal output end of the mode recognition module DET, and the other end of the third switch K3 is connected to the second input end VCC.

[0065] Figure 4 A circuit structure schematic diagram of a pattern recognition module in another embodiment of the present application is given as follows: Figure 4 As shown, in Figure 3 On the basis of the shown embodiment, the first control circuit 1 of the pattern recognition module described in this embodiment includes a first comparator COM1 and a first memory circuit, and the second control circuit 2 includes a second memory circuit, a first AND gate AND1 and a second AND gate AND2, wherein the first memory circuit includes a first RS trigger RS1 and a first inverter INV1, and the second memory circuit includes a second RS trigger RS2 and a second inverter INV2.

[0066] The first input terminal VS is connected to the ground through the resistor RVS by default, and when the VS terminal is left floating, VS is at a low level by default. The second input terminal VCC serves as the power supply terminal of the control chip to provide the power supply voltage for the control chip.

[0067] The non-inverting input terminal of the first comparator COM1 is connected to the first input terminal VS, the inverting input terminal of the first comparator COM1 is connected to the second input terminal VCC, the output terminal of the first comparator COM1 is connected to the set terminal of the first RS trigger RS1, the initial signal PG when the switching power supply is started is connected to the reset terminal of the first RS trigger RS1 through the first inverter INV1, and the output terminal of the first RS trigger RS1 is connected to the control terminal of the first switch K1, one end of the first switch K1 is connected to the first input terminal VS, and the other end of the first switch K1 is connected to the second input terminal VCC.

[0068] The non-inverting input terminal of the second comparator COM2 is connected to the first input terminal VS, the inverting input terminal of the second comparator COM2 is connected to the reference voltage VREF, the output terminal of the second comparator COM2 is connected to the set terminal of the second RS trigger RS2, the initial signal PG when the switching power supply is started is connected to the reset terminal of the second RS trigger RS2 through the second inverter INV2, and the output terminal of the second RS trigger RS2 is connected to one input terminal of the first AND gate AND1, and the initial signal PG when the switching power supply is started is connected to the other input terminal of the first AND gate AND1, and the output terminal of the first AND gate AND1 is connected to the control terminal of the second switch K2, one end of the second switch K2 is connected to the first input terminal VS, and the other end of the second switch K2 is connected to the feedback signal output terminal of the pattern recognition module DET.

[0069] The output end of the second RS trigger RS2 is also connected to an input end of the second AND gate AND2 through the third inverter INV3, the initial signal PG when the switching power supply is started is connected to the other input end of the second AND gate AND2, and the output end of the second AND gate AND2 is connected to the control end of the third switch K3, one end of the third switch K3 is connected to the feedback signal output end, and the other end of the third switch K3 is connected to the second input end VCC.

[0070] In this embodiment, the control signals of each switch are made more stable by adding the first memory circuit and the second memory circuit and the initial signal PG.

[0071] In other embodiments, the first memory circuit and the second memory circuit may also select other circuits with memory functions, such as: D trigger, JK trigger, latch, or integrated circuit of trigger and latch, etc., which is not limited in the embodiments of the present application.

[0072] Figure 5A circuit diagram of a control chip provided in an embodiment of the present application applied to a flyback switching power supply is given, such as Figure 5 As shown, the control chip is connected to the Flyback power supply peripheral circuit to form a flyback switching power supply circuit. When the control chip is applied to the flyback switching power supply, the first input terminal VS of the mode recognition module DET is directly connected to the power supply output terminal VOUT1, and the second input terminal VCC of the mode recognition module is connected to the ground terminal GND of the control chip through the capacitor C4.

[0073] This embodiment uses Figure 4 The schematic diagram shown in Figure 5 The working process of the present application is explained by taking the application in as an example: when the switching power supply is started, the high-voltage starting module HV starts to work, and first the VCC capacitor C4 is charged through the high-voltage starting module HV, and the voltage of the second input terminal VCC slowly rises. At the same time, the initial signal PG is low, the first RS trigger RS1 is reset to output a low level, the first switch K1 is disconnected, and the first AND gate AND1 and the second AND gate AND2 both output low-level signals. Therefore, the second switch K2 and the third switch K3 are both disconnected, until the control chip is started normally, the high-voltage starting module HV is turned off, the initialization signal PG turns to a high level, and at the same time, the voltage of the second input terminal VCC of the pattern recognition module DET decreases accordingly.

[0074] As the voltage of the second input terminal VCC decreases, until the voltage of the first input terminal VS is higher than the voltage of the VCC terminal, the first comparator COM1 outputs a high level, the first RS trigger RS1 is set to output a high level, the first switch K1 is closed, the first input terminal VS is connected to the second input terminal VCC, and the second input terminal VCC is powered by the power output terminal VOUT1 connected to the first input terminal VS, so that the control chip works normally.

[0075] After the control chip works normally, at this time, the voltage of the first input terminal VS is greater than the reference voltage VREF, the second comparator COM2 outputs a high level, the second RS trigger RS2 triggers and outputs a high level, and PG is high at this time, so the first AND gate AND1 outputs a high level, so that the second switch K2 is closed, and the second AND gate AND2 outputs a low level, so that the third switch K3 is disconnected, and the voltage signal of the first input terminal VS is output as a feedback signal through the feedback signal output terminal, and is finally connected to the feedback voltage detection module FB.

[0076] exist Figure 5In the flyback switching power supply shown, when the control chip starts normally and the voltage of the second input terminal VCC is stable, the mode recognition module DET connects the second input terminal VCC to the first input terminal VS through judgment, and the second input terminal VCC supplies power to the control chip through the first input terminal VS to ensure the normal operation of the control chip. At the same time, the input voltage of the first input terminal VS is connected to the feedback voltage detection module FB as a feedback signal.

[0077] The feedback voltage detection module FB connects the processed feedback signal to the PWM module and the oscillation circuit OSC to output a pulse-width modulated switching signal to the driving module DRV. The driving module DRV converts the switching signal into a driving signal and outputs it to Q1 to control the on and off time of Q1, thereby adjusting the pulse width or frequency of the power switching signal and ultimately obtaining a stable output voltage.

[0078] Figure 6 A circuit diagram of a control chip provided in an embodiment of the present application applied to a step-down switching power supply is given, such as Figure 6 As shown, the control chip is connected to the BUCK power supply peripheral circuit to form a step-down switching power supply circuit. When the control chip is applied to the step-down switching power supply, the first input terminal VS of the mode recognition module DET is suspended, the second input terminal VCC of the mode recognition module DET is connected to the power supply output terminal VOUT2 via the diode D2, and the second input terminal VCC of the mode recognition module DET is connected to the ground terminal GND of the control chip via the capacitor C2.

[0079] This embodiment uses Figure 4 The schematic diagram shown in Figure 6 The working process of this application is explained by taking the application in as an example: when the switching power supply is started, the control chip starts to work, firstly, the capacitor C2 of the second input terminal VCC is charged through the high-voltage startup module, and the voltage of the second input terminal VCC slowly rises. At the same time, since the initial signal PG is a low-level signal, the first RS trigger is reset to output a low-level signal, the first switch K1 is disconnected, and the first and second AND gates AND1 and AND2 both output low-level signals. Therefore, the second switch K2 and the third switch K3 are both disconnected. Until the control chip is started normally, the high-voltage startup module HV is turned off, the initial signal PG turns high, and the second input terminal VCC of the pattern recognition module DET is connected to the voltage of the power output terminal VOUT2 through the diode D2 to power the control chip.

[0080] After the control chip starts normally, at this time, since the initial signal PG turns to a high level, VS defaults to a low level, and the power output terminal VOUT2 is connected to the second input terminal VCC of the mode recognition module DET through the diode D2, therefore, the second input terminal VCC is a high level, so the outputs of the first comparator COM1 and the second comparator COM2 are both low levels, the first RS trigger and the second RS trigger are not set and both output low level signals, the first AND gate AND1 outputs a low level signal, and the second AND gate AND2 outputs a high level signal, therefore K1 and K2 are both disconnected, and K3 is closed, at this time, the voltage signal of the second input terminal VCC is output as a feedback signal through the feedback signal output terminal, and is finally connected to the feedback voltage detection module FB.

[0081] exist Figure 6 In the step-down switching power supply shown, when the control chip starts normally and the voltage of the second input terminal VCC is stable, the mode recognition module DET connects the voltage signal of the VCC terminal as a feedback signal to the feedback voltage detection module FB through judgment. The feedback voltage detection module FB connects the processed feedback signal to the PWM module and the oscillation circuit OSC to output a pulse-width modulated switching signal to the driving module DRV. The driving module DRV converts the switching signal into a driving signal and outputs it to Q1, controls the on and off time of Q1, thereby adjusting the pulse width or frequency of the power switch signal, and finally obtains a stable output voltage.

[0082] Apply Figure 5 and Figure 6 In the embodiment of the switching power supply circuit shown in FIG. 1 , the power switch tube Q1 is integrated into the control chip. Figure 5 In the flyback switching power supply shown in FIG. 1 , the control chip is connected to the primary coil through the collector C port of the power switch tube Q1, thereby being connected to the power supply circuit. Figure 6 In the step-down switching power supply shown in the figure, the control chip is connected to the power supply circuit through the collector C and emitter ports of the power switch tube Q1. Inside the control chip, the base B of the power switch tube Q1 is used as the control terminal, connected to the drive signal output terminal of the drive module DRV, and the emitter of the power switch tube Q1 is connected to the input terminal of the current detection module CS.

[0083] Figure 7 FIG. 1 is a schematic diagram of a package of an integrated design of a power switch tube and a control chip provided by an embodiment of the present application. Figure 7 As shown, the control chip of this embodiment adopts an 8-pin SOP (surface mount IC package) package, and the package structure includes a control chip internal circuit 9, a power switch tube Q1 and a package body 10, wherein the package body 10 covers the control chip internal circuit 9 and the power switch tube Q1. Among them, the control chip internal circuit 9 refers to the above control chip embodiment, which will not be repeated here.

[0084] The eight pins described in this embodiment are: a ground pin VSS, two second detection voltage input pins VCC, a first detection voltage input pin VS, and four high-voltage start signal input pins HV.

[0085] In this embodiment, the pins numbered 1-4 are arranged on one side of the control chip package structure, and the pins numbered 5-8 are arranged on the other side opposite to the control chip package structure, wherein:

[0086] The pins numbered 1 and 3 are connected together and are both the second detection voltage input pin VCC of the control chip. The pin is electrically connected to the second input terminal VCC of the control chip pattern recognition module and has the same function as the second input terminal VCC.

[0087] The pin numbered 4 is the first detection voltage input pin VS of the control chip. The pin is electrically connected to the first input terminal VS of the control chip pattern recognition module and has the same function as the first input terminal VS.

[0088] The pins numbered 5 to 8 are connected together and are the high-voltage startup signal input pins HV. The pins are electrically connected to the input end of the high-voltage startup module and have the same function as the high-voltage startup module.

[0089] The pin numbered 2 is a ground pin and is electrically connected to the ground terminal PVSS / VSS of the control chip.

[0090] Inside the control chip packaging structure, the emitter E of the power switch tube Q1 is connected to the current detection module CS, and the base B of the power switch tube Q1 is connected to the driving module DRV.

[0091] Figure 8 This is a schematic diagram of the packaging of the switch tube and control chip integrated design of the switching power supply provided by another embodiment of the present application. The control chip described in this embodiment adopts an 8-pin DIP (dual in-line package) package. The packaging structure includes an internal circuit 9 of the control chip, a power switch tube Q1 and a package body 10, wherein the package body 10 covers the internal circuit 9 of the control chip and the power switch tube Q1. Among them, the internal circuit 9 of the control chip can refer to the above control chip embodiment, which will not be repeated here.

[0092] The eight pins are: a ground pin VSS, a first detection voltage input pin VS, a second detection voltage input pin VCC, four high-voltage start signal input pins HV and a floating pin NC.

[0093] In this embodiment, the pins numbered 1-4 are arranged on one side of the control chip package structure, and the pins numbered 5-8 are arranged on the other side opposite to the control chip package structure, wherein:

[0094] The pin numbered 3 is the second detection voltage input pin VCC of the control chip mode recognition module. The pin is electrically connected to the second input terminal VCC of the control chip mode recognition module and has the same function as the second input terminal VCC.

[0095] The pin numbered 4 is the first detection voltage input pin VS of the control chip. The pin is electrically connected to the first input terminal VS of the control chip pattern recognition module and has the same function as the first input terminal VS.

[0096] The pins numbered 5 to 8 are connected together and are the high-voltage startup signal input pins HV. The pins are electrically connected to the input end of the high-voltage startup module and have the same function as the high-voltage startup module.

[0097] The pin numbered 1 is a ground pin, and is electrically connected to the ground terminal PVSS / VSS of the control chip.

[0098] The pin numbered 2 is left floating.

[0099] Inside the control chip packaging structure, the emitter E of the power switch tube Q1 is connected to the current detection module CS, and the base B of the power switch tube Q1 is connected to the driving module DRV.

[0100] It should be noted that in other embodiments, the power switch tube Q1 can also be externally placed on the control chip, and this application does not limit this.

[0101] The control chip of the embodiment of the present application can be applied to both a buck switching power supply and a flyback switching power supply, thereby realizing the versatility of the control chip. Figure 4 and Figure 5 The Buck (step-down) power supply circuit or Flyback (flyback) power supply circuit shown are both well-known technologies to those skilled in the art, and will not be described in detail in this application.

[0102] In summary, the control chip applied to the switching power supply of the present application is provided with a pattern recognition module, which can distinguish whether the connected one is a buck switching power supply circuit or a flyback switching power supply circuit, and output the connected voltage of the corresponding first input terminal or the second input terminal as a feedback signal according to different switching power supply circuits, so that the control chip can be applied to both the flyback switching power supply circuit and the buck switching power supply circuit, thereby improving the versatility and utilization rate of the control chip and reducing the manufacturing cost.

[0103] An embodiment of the present application also provides a switching power supply circuit, including a Buck power supply or a Flyback power supply, and the switching power supply circuit also includes the control chip described in the above embodiment, and the control chip is connected to the Buck power supply peripheral circuit to form a step-down switching power supply circuit; the control chip is connected to the Flyback circuit to form a flyback switching power supply circuit.

[0104] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0105] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A control chip for a switching power supply, comprising a feedback voltage detection module and a PWM module, wherein the feedback voltage detection module is used to detect a voltage signal at an output end of a power supply, the output end of the feedback voltage detection module is connected to the PWM module, and the PWM module is used to output a power switch signal after pulse width modulation; characterized in that: The control chip further includes a mode recognition module, the mode recognition module includes a first input terminal VS and a second input terminal VCC, and a feedback signal output terminal of the mode recognition module is connected to an input terminal of a feedback voltage detection module; When the control chip is connected to the flyback switching power supply circuit, the first input terminal VS is connected to the power supply output terminal, and the mode recognition module connects the first input terminal VS with the second input terminal VCC according to the input signals of the first input terminal VS and the second input terminal VCC to power the control chip, and outputs the voltage signal connected to the first input terminal VS as a feedback signal to the feedback voltage detection module; When the control chip is connected to a step-down switching power supply circuit, the first input terminal VS is suspended, the second input terminal VCC is connected to the power output terminal, and the second input terminal VCC serves as the power supply terminal of the control chip. The mode recognition module outputs the voltage signal connected to the second input terminal VCC as a feedback signal to the feedback voltage detection module based on the input signals of the first input terminal VS and the second input terminal VCC.

2. The control chip according to claim 1, characterized in that: The pattern recognition module includes a first control circuit and a second control circuit, and a first switch, a second switch and a third switch; The first switch is connected between the first input terminal and the second input terminal; The second switch is connected between the first input terminal and the feedback signal output terminal; The third switch is connected between the second input terminal and the feedback signal output terminal; The input end of the first control circuit is connected to the first input end and the second input end respectively, and the output end of the first control circuit is connected to the control end of the first switch; The input end of the second control circuit is respectively connected to the first input end and the reference voltage signal, and the output end of the second control circuit outputs two control signals, one of which is connected to the control end of the second switch, and the other is connected to the control end of the third switch; When the control chip is connected to the flyback switching power supply circuit, the first control circuit is used to control the first switch to be turned on, the second control circuit is used to control the second switch to be turned on, and the third switch to be turned off; When the control chip is connected to a step-down switching power supply circuit, the first control circuit is used to control the first switch to be turned off, the second control circuit is used to control the second switch to be turned off, and the third switch to be turned on.

3. The control chip according to claim 2, characterized in that: The first control circuit comprises a first comparator, a non-inverting input terminal of the first comparator is connected to a first input terminal, an inverting input terminal of the first comparator is connected to a second input terminal, and an output terminal of the first comparator is connected to a control terminal of a first switch; The second control circuit includes a second comparator and a third inverter, the non-inverting input of the second comparator is connected to the first input, the inverting input of the second comparator is connected to a reference voltage, the output of the second comparator is connected to the control end of the second switch, and the output of the second comparator is connected to the control end of the third switch through the third inverter.

4. The control chip according to claim 3, characterized in that: The first control circuit further includes a first memory circuit, and the second control circuit further includes a second memory circuit, a first AND gate and a second AND gate; The first memory circuit is connected between the first comparator and the first switch, the output signal of the first comparator and the initial signal when the switch power supply is started are respectively connected to the two input ends of the first memory circuit, and the output end of the first memory circuit is connected to the control end of the first switch; The output signal of the second comparator and the initial signal when the switch power supply is started are respectively connected to two input terminals of the second memory circuit, and the output terminal of the second memory circuit outputs two control signals, one of which is connected to one input terminal of the first AND gate, and the other is connected to one input terminal of the second AND gate through the third inverter; The other input ends of the first AND gate and the second AND gate are both connected to the initial signal when the switching power supply is started, and the output end of the first AND gate is connected to the control end of the second switch, and the output end of the second AND gate is connected to the control end of the third switch.

5. The control chip according to claim 4, characterized in that: The first memory circuit includes a first RS flip-flop and a first inverter, and the second memory circuit includes a second RS flip-flop and a second inverter; The set end of the first RS trigger is connected to the output signal of the first comparator, the initial signal when the switching power supply is started is connected to the reset end of the first RS trigger through the first inverter, and the output end of the first RS trigger is connected to the control end of the first switch; The set end of the second RS trigger is connected to the output signal of the second comparator, the initial signal when the switching power supply is started is connected to the reset end of the second RS trigger through the second inverter, and the output end of the second RS trigger is connected to an input end of the first AND gate, and is connected to an input end of the second AND gate through the third inverter.

6. The control chip according to claim 1, characterized in that: When the control chip is connected to a flyback switching power supply circuit, the second input terminal VCC is connected to the ground terminal of the control chip through the first capacitor; when the control chip is connected to a step-down switching power supply circuit, the second input terminal VCC is connected to the ground terminal of the control chip through the second capacitor.

7. The control chip according to claim 6, characterized in that: The control chip includes a high-voltage startup circuit, the input end of the high-voltage startup circuit is connected to the power input end, the output end of the high-voltage startup circuit is connected to the second input end VCC, and the high-voltage startup circuit is used to charge the second capacitor of the second input end VCC when the system is powered on, so that the control chip starts normally.

8. The control chip according to claim 1, characterized in that: The control chip also includes an oscillation circuit, the input end of the oscillation circuit is connected to the output end of the feedback voltage detection module, the output end of the oscillation circuit is connected to the PWM module, the oscillation circuit is used to generate an operating frequency of the switching power supply circuit, and the PWM module adjusts the frequency of the power switch signal according to the operating frequency.

9. The control chip according to claim 1, characterized in that: The control chip includes a protection module, which is connected to the PWM module. The protection module is used to send a signal to the PWM module when a system abnormality is detected, so that the power switch tube is turned off by the PWM module.

10. The control chip according to claim 1, characterized in that: The control chip also includes a drive circuit, a drive signal output end of the drive circuit is connected to the control end of the power switch tube, the power switch tube is connected in series in the power loop of the switching power supply circuit, the input end of the drive circuit is connected to the PWM signal output end of the PWM module, the drive circuit is used to convert the power switch signal into a drive signal to control the on and off of the power switch tube, and the power switch tube is integrated inside the control chip, or serves as a peripheral circuit of the control chip.

11. The control chip according to any one of claims 1 to 10, characterized in that: The control chip is packaged in a dual in-line package or a surface mount IC package.

12. The control chip according to claim 11, characterized in that: The control chip is provided with a plurality of pins, including: a ground terminal pin, a first detection voltage input pin, a second detection voltage input pin and a high-voltage start signal input pin.

13. A switching power supply circuit, comprising a Buck switching power supply or a Flyback switching power supply, characterized in that: The switching power supply circuit also includes a control chip as described in any one of claims 1-12, and the control chip is connected to the Buck switching power supply peripheral circuit to form a step-down switching power supply; the control chip is connected to the Flyback switching power supply peripheral circuit to form a flyback switching power supply circuit.

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