Control circuit, control chip and power supply system

Abstract

The present invention provides a control circuit, a control chip, and a power supply system, comprising: a first end of a first resistor connected to a high-voltage terminal of a control circuit, and a second end connected to the first ends of first and second switches; a second end of the first switch connected to a sampling terminal of the control circuit via a second resistor; a second end of the second switch connected to ground via a third resistor; an input end of a first operational amplifier connected to the first end of the first switch and a first reference voltage, outputting a first detection signal; an input end of a second operational amplifier connected to the second end of the second switch and a second reference voltage, outputting a second detection signal; a logic control module generating a control signal based on the first and second detection signals; and a drive module generating a drive signal based on the control signal; wherein the switching signal of the second switch is opposite to that of the first switch. The present invention utilizes the first resistor to implement both voltage detection and overcurrent compensation functions, thereby reducing costs, saving space, and improving reliability.

Description

Technical Field

[0001] The present invention relates to the field of power supply design, and in particular to a control circuit, a control chip and a power supply system. Background Art

[0002] In existing power supply systems, if the control chip needs to have both voltage detection and overcurrent compensation functions, the two are generally separated, with two pins used to detect voltage signals and current signals respectively, and the detected voltage signals and current signals are processed to achieve these two functions. Figure 1 As shown, the control chip 1 is connected to the detection signal of the input voltage Vin (obtained by voltage division by resistors Ra and Rb) through the VIN pin, and the detection signal of the input voltage Vin is compared with the reference signal Vdet based on the first op amp 11; the control chip 1 is also connected to the detection signal of the inductor current (obtained by sampling by resistor Rc) through the CS pin. The overcurrent compensation module 13 adds the compensation signal to the CS pin and compares the signal on the CS pin with the reference signal Vocp based on the second op amp 12; the logic control module 14 generates a control signal based on the output signals of the two op amps, and the drive module 15 drives the power switch tube Q based on the control signal to achieve power conversion. In addition, the internal power supply module 16 obtains power from the high voltage terminal HV and converts it into an internal operating voltage to power the various modules in the control chip 1.

[0003] As can be seen, voltage detection must be performed through an additional pin, VIN, and requires additional detection components (resistors Ra and Rb), increasing cost and taking up space. Furthermore, the implementation of overcurrent compensation is complex, making it difficult to achieve simple and reliable implementation.

[0004] Therefore, how to realize multiple functions simultaneously without increasing the number of pins, simplify the implementation method and improve reliability has become one of the problems that need to be solved urgently by those skilled in the art. Summary of the Invention

[0005] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a control circuit, a control chip and a power supply system to solve the problems of high cost, complex implementation and poor reliability of the power supply system in the prior art.

[0006] To achieve the above-mentioned and other related objectives, the present invention provides a control circuit for controlling a switching power supply circuit, the control circuit comprising at least:

[0007] A first resistor, a second resistor, a third resistor, a first switch, a second switch, a first operational amplifier, a second operational amplifier, a logic control module, and a driving module;

[0008] A first end of the first resistor is connected to the high voltage end of the control circuit, and a second end thereof is connected to the first ends of the first switch and the second switch;

[0009] The second end of the first switch is connected to the sampling end of the control circuit via the second resistor;

[0010] The second end of the second switch is grounded via the third resistor;

[0011] The first input terminal of the first operational amplifier is connected to the first terminal of the first switch, the second input terminal receives a first reference voltage, and outputs a first detection signal;

[0012] The first input terminal of the second operational amplifier is connected to the second terminal of the second switch, the second input terminal receives a second reference voltage, and outputs a second detection signal;

[0013] The logic control module is connected to the output terminals of the first operational amplifier and the second operational amplifier, and generates a control signal based on the first detection signal and the second detection signal;

[0014] The driving module is connected to the output end of the logic control module and generates a driving signal based on the control signal;

[0015] The switching signals of the first switch and the second switch are opposite.

[0016] Optionally, the control circuit further includes a voltage follower connected between the sampling terminal and the second resistor.

[0017] More optionally, the control circuit further includes a leading edge blanking module, and the leading edge blanking module is connected between the sampling end and the voltage follower.

[0018] Optionally, the control ends of the first switch and the second switch are connected to the logic control module, and the switch signal is obtained from the logic control module.

[0019] More optionally, the control circuit also includes a junction field effect transistor and an operating voltage generating module; the drain of the junction field effect transistor is connected to the high voltage end, the source is connected to the operating voltage generating module, and the gate is grounded; the operating voltage generating module obtains electrical energy from the source of the junction field effect transistor and converts it into an operating voltage to power each module in the control circuit.

[0020] More optionally, the first resistor is a channel resistance of the junction field effect transistor.

[0021] To achieve the above-mentioned purpose and other related purposes, the present invention also provides a control chip, which at least includes: the above-mentioned control circuit, a high-voltage pin connected to the high-voltage end, a sampling pin connected to the sampling end, and a driving pin connected to the output end of the driving module.

[0022] To achieve the above-mentioned and other related objectives, the present invention further provides a power supply system, which comprises at least:

[0023] Switching power supply circuit and the above control circuit;

[0024] The control circuit is connected to the switching power supply circuit and provides a driving signal for the power switch tube in the switching power supply circuit; wherein, the high-voltage end of the control circuit is connected to the input voltage of the switching power supply circuit, and the sampling end of the control circuit is connected to the sampling point of the inductor current in the switching power supply circuit; when the power switch tube is turned on, the first switch is closed and the second switch is opened; when the power switch tube is turned off, the first switch is opened and the second switch is closed.

[0025] To achieve the above-mentioned and other related objectives, the present invention further provides a power supply system, which comprises at least:

[0026] Switching power supply circuit and the above control circuit;

[0027] The control circuit is connected to the switching power supply circuit and provides a driving signal for the power switch tube in the switching power supply circuit; wherein, the high-voltage end of the control circuit is connected to the output voltage of the switching power supply circuit, and the sampling end of the control circuit is connected to the sampling point of the inductor current in the switching power supply circuit; when the power switch tube is turned on, the first switch is closed and the second switch is opened; when the power switch tube is turned off, the first switch is opened and the second switch is closed.

[0028] Optionally, the switching power supply circuit is a BUCK topology structure, a BOOST topology structure or a BUCK-BOOST topology structure.

[0029] As described above, the control circuit, control chip, and power supply system of the present invention have the following beneficial effects:

[0030] The control circuit, control chip, and power supply system of the present invention utilize a first resistor to implement both a voltage detection function and an overcurrent compensation function. Only one detection pin (for detecting the inductor current) is required on the periphery of the chip, and the overcurrent compensation function is implemented in a simple and reliable manner. This reduces costs, saves space, and improves reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1It shows a schematic structural diagram of a power supply system in the prior art.

[0032] Figure 2 Shown is a structural schematic diagram of the control circuit and control chip of the present invention.

[0033] Figure 3 Shown is a first structural schematic diagram of the power supply system of the present invention.

[0034] Figure 4 It shows a second structural schematic diagram of the power supply system of the present invention.

[0035] Figure 5 It shows a third structural schematic diagram of the power supply system of the present invention.

[0036] Figure 6 It shows a fourth structural schematic diagram of the power supply system of the present invention.

[0037] Figure 7 It shows a fifth structural schematic diagram of the power supply system of the present invention.

[0038] Component number description

[0039] 1. Control chip

[0040] 11. First op amp

[0041] 12 Second op amp

[0042] 13 Overcurrent compensation module

[0043] 14 Logic Control Module

[0044] 15 Driver Module

[0045] 16 Internal power supply module

[0046] 2 Control circuit

[0047] 21 First operational amplifier

[0048] 22 Second operational amplifier

[0049] 23 Logic Control Module

[0050] 24 Driver Module

[0051] 25 Voltage Follower

[0052] 26 Leading-Edge Blanking Module

[0053] 27 Inverter

[0054] 28 working voltage generation module DETAILED DESCRIPTION

[0055] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0056] See also Figures 2 to 7 It should be noted that the diagrams provided in this embodiment are merely schematic illustrations of the basic concept of the present invention. Therefore, the diagrams only show components related to the present invention and are not drawn according to the number, shape, and size of components in actual implementation. In actual implementation, the type, quantity, and proportion of each component may be changed arbitrarily, and the component layout may also be more complex.

[0057] Example 1

[0058] like Figure 2 As shown, this embodiment provides a control circuit 2 for controlling a switching power supply circuit. The control circuit 2 includes:

[0059] a first resistor R1 , a second resistor R2 , a third resistor R3 , a first switch SW1 , a second switch SW2 , a first operational amplifier 21 , a second operational amplifier 22 , a logic control module 23 and a driving module 24 .

[0060] like Figure 2 As shown, a first end of the first resistor R1 is connected to the high voltage end of the control circuit 2 , and a second end thereof is connected to the first ends of the first switch SW1 and the second switch SW2 .

[0061] Specifically, the type of the first resistor R1 is not limited, and it can be connected between the high voltage end of the control circuit 2 and the first ends of the first switch SW1 and the second switch SW2, and realize voltage division with the second resistor R2 and the third resistor R3 respectively.

[0062] like Figure 2 As shown, as another implementation of the present invention, the control circuit 2 further includes a junction field effect transistor JEFT and an operating voltage generating module 28. The drain of the junction field effect transistor JEFT is connected to the high voltage terminal, the source is connected to the operating voltage generating module 28, and the gate is grounded. The operating voltage generating module 28 obtains electrical energy from the source of the junction field effect transistor JEFT and converts it into an operating voltage to power each module in the control circuit 2. In this case, the first resistor R1 can be prepared in the junction field effect transistor JEFT and implemented by the channel resistance in the junction field effect transistor JEFT.

[0063] like Figure 2 As shown, the second end of the first switch SW1 is connected to the sampling end of the control circuit 2 via the second resistor R2; the second end of the second switch SW2 is grounded via the third resistor R3.

[0064] Specifically, the switching signal of the second switch SW2 is opposite to that of the first switch SW1 , and the switching signal is inverted by the inverter 27 . In this embodiment, the switching signals of the first switch SW1 and the second switch SW2 are provided by the logic control module 23 .

[0065] like Figure 2 As shown, as an implementation of the present invention, the control circuit 2 further includes a voltage follower 25, which is connected between the sampling terminal and the second resistor R2. As an example, the voltage follower 25 is implemented using an operational amplifier, whose non-inverting input terminal is connected to the sampling terminal, and whose inverting input terminal and output terminal are connected to the second resistor R2. Furthermore, the control circuit 2 further includes a leading edge blanking module 26, which is connected between the sampling terminal and the input terminal of the voltage follower 25.

[0066] like Figure 2 As shown, the first input terminal of the first operational amplifier 21 is connected to the first end of the first switch SW1 , the second input terminal receives the first reference voltage Vocp, and outputs a first detection signal.

[0067] Specifically, in this embodiment, the non-inverting input terminal of the first operational amplifier 21 is connected to the first end of the first switch SW1, and the inverting input terminal is connected to the first reference voltage Vocp; in actual use, the corresponding relationship between the input terminal polarity and the input signal can be set as needed, and is not limited to this embodiment.

[0068] like Figure 2 As shown, the first input terminal of the second operational amplifier 22 is connected to the second terminal of the second switch SW2 , the second input terminal receives the second reference voltage Vdet, and outputs a second detection signal.

[0069] Specifically, in this embodiment, the non-inverting input terminal of the second operational amplifier 22 is connected to the second end of the second switch SW2, and the inverting input terminal is connected to the second reference voltage Vdet; in actual use, the corresponding relationship between the input terminal polarity and the input signal can be set as needed, and is not limited to this embodiment.

[0070] It should be noted that the detection signal output by the second operational amplifier 22 can be used for, including but not limited to, voltage detection, overvoltage protection or undervoltage protection, and the value of the second reference voltage Vdet can be set as needed.

[0071] like Figure 2 As shown, the logic control module 23 is connected to the output ends of the first operational amplifier 21 and the second operational amplifier 22 , and generates a control signal based on the first detection signal and the second detection signal.

[0072] It should be noted that any module that can generate the control signal based on the detection signal is applicable to the present invention, and will not be described in detail here.

[0073] like Figure 2 As shown, the driving module 24 is connected to the output end of the logic control module 23 and generates a driving signal based on the control signal.

[0074] like Figure 2 As shown, this embodiment further provides a control chip, which includes: the control circuit 2, a high-voltage pin HV, a sampling pin CS, and a driving pin GATE.

[0075] Specifically, the high-voltage pin HV is connected to the high-voltage terminal of the control circuit 2 for obtaining a high-voltage signal. The sampling pin CS is connected to the sampling terminal of the control circuit 2 for obtaining an inductor current sampling signal. The drive pin GATE is connected to the output terminal of the drive module 24 for driving an external power switch.

[0076] Specifically, in this embodiment, the input end of the working voltage generating module 28 is also connected to the working voltage pin VCC for connecting an external capacitor.

[0077] like Figure 2 As shown, as one working principle of the present invention, when the power switch tube is turned on, the first switch SW1 is closed and the second switch SW2 is opened, and the control circuit 2 uses the voltage division of the first resistor R1 and the second resistor R2 to implement an overcurrent compensation function. When the power switch tube is turned off, the first switch SW1 is opened and the second switch SW2 is closed, and the control circuit 2 uses the voltage division of the first resistor R1 and the third resistor R3 to implement voltage detection or overvoltage protection or undervoltage protection.

[0078] Example 2

[0079] like Figure 3 As shown, this embodiment provides a power supply system, which includes:

[0080] A switching power supply circuit and a control circuit 2 of Example 1; the control circuit 2 is connected to the switching power supply circuit to provide a drive signal for the power switch tube in the switching power supply circuit; wherein the high-voltage terminal of the control circuit is connected to the input voltage Vin of the switching power supply circuit, and the sampling terminal of the control circuit is connected to the sampling point of the inductor current in the switching power supply circuit; when the power switch tube is turned on, the first switch in the control circuit 2 is closed and the second switch is opened; when the power switch tube is turned off, the first switch in the control circuit 2 is opened and the second switch is closed.

[0081] Specifically, the switching power supply circuit is a BUCK topology. As an example, the BUCK topology includes a first capacitor C1, a load LOAD, an inductor L, a diode D, a power switch Q, and a sampling resistor Rc; the first capacitor C1 provides an input voltage Vin (the front-stage rectifier module is not shown); one end of the load LOAD is connected to the input voltage Vin, and the other end is connected to the first end of the inductor L; the second end of the inductor L is connected to the drain of the power switch Q; the cathode of the diode D is connected to the input voltage Vin, and the anode is connected to the drain of the power switch Q; the gate of the power switch Q is connected to the drive signal output by the control circuit 2, and the source is grounded via the sampling resistor Rc.

[0082] Specifically, the high-voltage terminal of the control circuit 2 is connected to the input voltage Vin, and the sampling terminal is connected to the source of the power switch Q. The input terminal of the operating voltage generation module 28 of the control circuit 2 is also connected to the second capacitor C2. The specific structure of the control circuit 2 is described in Example 1 and is not detailed here.

[0083] Example 3

[0084] like Figure 4 As shown, this embodiment provides a power supply system, which is different from the second embodiment in that the switching power supply circuit is a BOOST topology structure.

[0085] Specifically, as an example, the BOOST topology includes a first capacitor C1, an inductor L, a diode D, a load LOAD, a power switch tube Q and a sampling resistor Rc; the first capacitor C1 provides an input voltage Vin (the front-stage rectifier module is not shown); one end of the inductor L is connected to the input voltage Vin, and the other end is connected to the positive electrode of the diode D; the negative electrode of the diode D is grounded via the load LOAD; the drain of the power switch tube Q is connected to the positive electrode of the diode D, the gate is connected to the drive signal output by the control circuit 2, and the source is grounded via the sampling resistor Rc.

[0086] It should be noted that other structures and principles are the same as those in the second embodiment and will not be described in detail here.

[0087] Example 4

[0088] like Figure 5 As shown, this embodiment provides a power supply system, which is different from the second and third embodiments in that the switching power supply circuit is a BUCK-BOOST topology structure.

[0089] Specifically, as an example, the BUCK-BOOST topology includes a first capacitor C1, an inductor L, a diode D, a load LOAD, a power switch tube Q and a sampling resistor Rc; the first capacitor C1 provides an input voltage Vin (the front-stage rectifier module is not shown); one end of the inductor L is connected to the input voltage Vin, and the other end is connected to the positive electrode of the diode D; the negative electrode of the diode D is connected to the input voltage Vin via the load LOAD; the drain of the power switch tube Q is connected to the positive electrode of the diode D, the gate is connected to the drive signal output by the control circuit 2, and the source is grounded via the sampling resistor Rc.

[0090] It should be noted that other structures and principles are the same as those in the second embodiment and will not be described in detail here.

[0091] Example 5

[0092] like Figure 6 and Figure 7 As shown, this embodiment provides a power supply system, which is different from the second, third and fourth embodiments in that the high voltage end of the control circuit 2 is connected to the output voltage of the switching power supply circuit.

[0093] As an example, Figure 6 As shown in FIG, in the switching power supply circuit based on the BOOST topology structure, the high voltage end of the control circuit 2 is connected to the cathode of the diode D. Figure 7 As shown, in the switching power supply circuit based on the BUCK-BOOST topology structure, the high voltage end of the control circuit 2 is connected to the cathode of the diode D.

[0094] It should be noted that other structures and principles are the same as those in the second embodiment and will not be described in detail here.

[0095] In summary, the present invention provides a control circuit, a control chip, and a power supply system, comprising: a first resistor, a second resistor, a third resistor, a first switch, a second switch, a first operational amplifier, a second operational amplifier, a logic control module, and a drive module; the first end of the first resistor is connected to the high voltage end of the control circuit, and the second end is connected to the first ends of the first switch and the second switch; the second end of the first switch is connected to the sampling end of the control circuit via the second resistor; the second end of the second switch is grounded via the third resistor; the first input end of the first operational amplifier is connected to the first end of the first switch, the second input end receives a first reference voltage, and outputs a first detection signal; the first input end of the second operational amplifier is connected to the second end of the second switch, the second input end receives a second reference voltage, and outputs a second detection signal; the logic control module is connected to the output ends of the first operational amplifier and the second operational amplifier, and generates a control signal based on the first detection signal and the second detection signal; the drive module is connected to the output end of the logic control module, and generates a drive signal based on the control signal; wherein the switching signal of the second switch is opposite to that of the first switch. The control circuit, control chip, and power supply system of the present invention utilize a first resistor to implement both voltage detection and overcurrent compensation. Only one detection pin (for detecting inductor current) is required on the chip periphery, and the overcurrent compensation function is implemented in a simple and reliable manner. This reduces costs, saves space, and improves reliability. Therefore, the present invention effectively overcomes the shortcomings of the prior art and has high industrial value.

[0096] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A control circuit for controlling a switching power supply circuit, characterized in that: The control circuit at least includes: A first resistor, a second resistor, a third resistor, a first switch, a second switch, a first operational amplifier, a second operational amplifier, a logic control module, and a driving module; A first end of the first resistor is connected to the high voltage end of the control circuit, and a second end thereof is connected to the first ends of the first switch and the second switch; The second end of the first switch is connected to the sampling end of the control circuit via the second resistor; The second end of the second switch is grounded via the third resistor; The first input terminal of the first operational amplifier is connected to the first terminal of the first switch, the second input terminal receives a first reference voltage, and outputs a first detection signal; The first input terminal of the second operational amplifier is connected to the second terminal of the second switch, the second input terminal receives a second reference voltage, and outputs a second detection signal; The logic control module is connected to the output terminals of the first operational amplifier and the second operational amplifier, and generates a control signal based on the first detection signal and the second detection signal; The driving module is connected to the output end of the logic control module and generates a driving signal based on the control signal; The switching signals of the first switch and the second switch are opposite.

2. The control circuit according to claim 1, wherein: The control circuit further includes a voltage follower connected between the sampling terminal and the second resistor.

3. The control circuit according to claim 2, wherein: The control circuit further includes a leading edge blanking module connected between the sampling terminal and the input terminal of the voltage follower.

4. The control circuit according to claim 1, wherein: The control ends of the first switch and the second switch are connected to the logic control module, and obtain the switch signal from the logic control module.

5. The control circuit according to any one of claims 1 to 4, characterized in that: The control circuit also includes a junction field-effect transistor and an operating voltage generating module; the drain of the junction field-effect transistor is connected to the high-voltage terminal, the source is connected to the operating voltage generating module, and the gate is grounded; the operating voltage generating module obtains electrical energy from the source of the junction field-effect transistor and converts it into an operating voltage to power each module in the control circuit.

6. The control circuit according to claim 5, wherein: The first resistor is a channel resistance of the junction field effect transistor.

7. A control chip, characterized in that: The control chip at least includes: the control circuit according to any one of claims 1 to 6, a high-voltage pin connected to the high-voltage end, a sampling pin connected to the sampling end, and a driving pin connected to the output end of the driving module.

8. A power supply system, characterized in that: The power supply system at least includes: A switching power supply circuit and a control circuit as claimed in any one of claims 1 to 6; The control circuit is connected to the switching power supply circuit and provides a driving signal for the power switch tube in the switching power supply circuit; wherein, the high-voltage end of the control circuit is connected to the input voltage of the switching power supply circuit, and the sampling end of the control circuit is connected to the sampling point of the inductor current in the switching power supply circuit; when the power switch tube is turned on, the first switch is closed and the second switch is opened; when the power switch tube is turned off, the first switch is opened and the second switch is closed.

9. A power supply system, characterized in that: The power supply system at least includes: A switching power supply circuit and a control circuit as claimed in any one of claims 1 to 6; The control circuit is connected to the switching power supply circuit and provides a driving signal for the power switch tube in the switching power supply circuit; wherein, the high-voltage end of the control circuit is connected to the output voltage of the switching power supply circuit, and the sampling end of the control circuit is connected to the sampling point of the inductor current in the switching power supply circuit; when the power switch tube is turned on, the first switch is closed and the second switch is opened; when the power switch tube is turned off, the first switch is opened and the second switch is closed.

10. The power supply system according to claim 8 or 9, characterized in that: The switching power supply circuit is a BUCK topology structure, a BOOST topology structure or a BUCK-BOOST topology structure.

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