Long-time reset circuit of switching power supply, printed circuit board and electronic device

Abstract

The application discloses a long-time reset circuit of a switching power supply, a printed circuit board and electronic equipment, which comprises an electric switching circuit, a reset signal maintaining circuit and a power supply energy storage circuit, a power supply input end, a power supply switching circuit and a power supply pin of a chip are sequentially connected; the reset signal maintaining circuit is connected with the power supply switching circuit; the power supply energy storage circuit is connected with the power supply input end and the reset signal maintaining circuit respectively; after receiving a reset signal, the reset signal maintaining circuit outputs an off signal to the power supply switching circuit, so that the power supply switching circuit is turned off, the power supply to the chip is cut off, the power supply energy storage circuit is discharged through the reset signal maintaining circuit, after the discharge, the reset signal maintaining circuit stops outputting the off signal, the power supply switching circuit is reconnected to supply power to the power supply pin of the chip, the reset circuit is simple in reset control and simple in structure, does not need to be configured with an independent auxiliary power supply, does not need to increase a switch on a main power supply output path, can reduce the area occupied by the board and reduce the cost.

Description

Technical Field

[0001] This invention relates to the field of switching power supply technology, and in particular to a long-time reset circuit, printed circuit board, and electronic device for a switching power supply. Background Technology

[0002] In current electronic products, the load of switching power supplies often contains critical chips. These critical chips sometimes need to be reset and restarted. The most effective and universal method for chip reset is to cut off the power supply for a period of time and then re-energize it, allowing the chip to restart naturally. This requires that when a chip needs to be reset, the system sends a command to the reset circuit. Upon receiving the command, the reset circuit, for a period of time, cuts off the power supply to the chip and other loads.

[0003] For small and medium-sized systems and power supplies with low to medium power, the circuit functions are simple and there is no management system in the power supply, making it difficult to implement the reset function. For example, it is necessary to configure a control circuit in conjunction with an energy storage circuit, use an independent auxiliary power supply, or add a switch at the power output terminal. Configuring a control circuit in conjunction with an energy storage circuit or using an independent auxiliary power supply will make the power supply circuit structure less concise, resulting in a large board area. Adding a switch at the power output terminal requires additional management, which leads to complex control, reduced power supply efficiency, and decreased reliability of the switching power supply. Summary of the Invention

[0004] The purpose of this invention is to at least solve one of the technical problems existing in the prior art, and to provide a long-term reset circuit, printed circuit board and electronic device for switching power supply, which has a simple circuit, simple reset control and low cost.

[0005] In a first aspect, embodiments of the present invention provide a long-term reset circuit for a switching power supply, comprising:

[0006] A power supply switch circuit, wherein the input terminal of the power supply switch circuit is connected to the power input terminal, and the output terminal of the power supply switch circuit is connected to the power supply pin of the chip;

[0007] A reset signal sustaining circuit is connected to the power supply switch circuit, and the reset signal sustaining circuit is used to output a shutdown signal to the power supply switch circuit when a reset signal is received.

[0008] A power supply and energy storage circuit is connected to the power input terminal and the reset signal sustaining circuit. The power supply and energy storage circuit is used to discharge through the reset signal sustaining circuit when the power supply switch circuit is turned off, so that the reset signal sustaining circuit stops outputting the turn-off signal after the power supply and energy storage circuit discharges.

[0009] In a second aspect, embodiments of the present invention provide a printed circuit board including a long-time reset circuit for a switching power supply as described in the first aspect embodiment above.

[0010] Thirdly, embodiments of the present invention provide an electronic device, including a long-time reset circuit of a switching power supply as described in the first aspect embodiment above, or including a printed circuit board as described in the second aspect embodiment above.

[0011] This invention includes: a long-term reset circuit for a switching power supply, a printed circuit board, and electronic equipment. After receiving a reset signal, the reset signal sustaining circuit outputs a shutdown signal to the power supply switching circuit, causing the power supply switching circuit to shut down and cut off the power supply to the chip's power pins. Then, the power supply energy storage circuit discharges through the reset signal sustaining circuit. After the power supply energy storage circuit discharges, the reset signal sustaining circuit stops outputting the shutdown signal, and the power supply switching circuit is reconnected to supply power to the chip's power pins. Through the cooperation between the reset signal sustaining circuit and the power supply energy storage circuit, a long-term reset of the power supply switching circuit is achieved, thereby achieving a long-term reset of the chip. This reset circuit has simple reset control and a concise structure, does not require an independent auxiliary power supply, and does not require adding a switch to the main power output circuit, thus reducing board area and cost.

[0012] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0013] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0014] Figure 1 This is a schematic diagram of a long-time reset circuit for a switching power supply provided in Embodiment 1 of the present invention;

[0015] Figure 2 This is a schematic diagram of a long-time reset circuit for a switching power supply provided in Embodiment 2 of the present invention;

[0016] Figure 3 This is a schematic diagram of a long-time reset circuit for a switching power supply provided in Embodiment 3 of the present invention;

[0017] Figure 4 This is a schematic diagram of a long-time reset circuit for a switching power supply provided in Embodiment 4 of the present invention;

[0018] Figure 5 This is a schematic diagram of a long-time reset circuit for a switching power supply provided in Embodiment 5 of the present invention. Detailed Implementation

[0019] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0020] In the description of this invention, the use of "first" and "second" is for the purpose of distinguishing technical features only, and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0021] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0022] This invention provides a long-term reset circuit, printed circuit board, and electronic device for a switching power supply. The circuit is simple, the reset control is easy, and the cost is low.

[0023] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0024] Reference Figure 1 A first aspect of the present invention provides a long-term reset circuit for a switching power supply, comprising a power supply switching circuit 100, a reset signal sustaining circuit 200, and a power supply energy storage circuit 300, wherein:

[0025] The input terminal of the power supply switch circuit 100 is connected to the power input terminal, and the output terminal of the power supply switch circuit 100 is connected to the power supply pin of the chip.

[0026] The reset signal sustaining circuit 200 is connected to the power supply switch circuit 100. The reset signal sustaining circuit 200 is used to output a shutdown signal to the power supply switch circuit 100 when a reset signal is received.

[0027] The power supply and energy storage circuit 300 is connected to the power input terminal and the reset signal maintenance circuit 200 respectively. The power supply and energy storage circuit 300 is used to discharge through the reset signal maintenance circuit 200 when the power supply switch circuit 100 is turned off, so that the reset signal maintenance circuit 200 stops outputting the turn-off signal after the power supply and energy storage circuit 300 discharges.

[0028] The long-term reset circuit of the switching power supply provided in this embodiment has the following characteristics: After receiving a reset signal, the reset signal holding circuit 200 outputs a shutdown signal to the power supply switching circuit 100, causing the power supply switching circuit 100 to shut down and cut off the power supply to the chip's power pins. Then, the power supply energy storage circuit 300 discharges through the reset signal holding circuit 200. After the power supply energy storage circuit 300 discharges, the reset signal holding circuit 200 stops outputting the shutdown signal, and the power supply switching circuit 100 is reconnected to supply power to the chip's power pins. Through the cooperation between the reset signal holding circuit 200 and the power supply energy storage circuit 300, a long-term reset of the power supply switching circuit 100 is achieved, thereby achieving a long-term reset of the chip. This reset circuit has simple reset control and a concise structure. It does not require an independent auxiliary power supply or an additional switch on the main power output line, which can reduce the board area and lower the cost.

[0029] Reference Figure 2 In the aforementioned long-time reset circuit of the switching power supply, the power supply switching circuit 100 includes a first switching transistor Q1 and a first diode D1. This reset circuit draws power from the primary winding of transformer T1. Pin 6 of transformer T1 serves as the power input terminal of this reset circuit and is connected to the anode of the first diode D1. The cathode of the first diode D1 is connected to one switching pin of the first switching transistor Q1, and the other switching pin of the first switching transistor Q1 is connected to the power supply pin of chip M1. The control pin of the first switching transistor Q1 is connected to the reset signal sustaining circuit 200. It can be understood that when the power supply switching circuit 100 is on, i.e., when the first switching transistor Q1 is on, the electrical energy provided by the primary winding of transformer T1 is transmitted to the power supply pin of chip M1 through the first diode D1 and the first switching transistor Q1, enabling chip M1 to operate normally. If the reset signal sustaining circuit 200 receives the reset signal RESET, it will output a low-level turn-off signal to the base of the first switching transistor Q1, causing the first switching transistor Q1 to turn off, thereby cutting off the power supply to the power supply pin of chip M1. Figure 2 The first switching transistor Q1 is an NPN transistor, that is, the cathode of the first diode D1 is connected to the collector of the first switching transistor Q1, the emitter of the first switching transistor Q1 is connected to the power supply pin of the chip M1, and the base of the first switching transistor Q1 is connected to the reset signal holding circuit 200.

[0030] Reference Figure 2In the long-term reset circuit of the aforementioned switching power supply, the reset signal sustaining circuit 200 includes a reset signal input terminal, a shutdown signal output terminal, a second switch Q2, a third switch Q3, a second resistor R2, and a second capacitor C2. The reset signal input terminal is connected to one end of the second resistor R2, one end of the second capacitor C2, one switch pin of the second switch Q2, and the control pin of the third switch Q3, respectively. The other end of the second resistor R2, the other end of the second capacitor C2, and one switch pin of the third switch Q3 are grounded. The other switch pin of the third switch Q3 is connected to the control pin of the second switch Q2. The other switch pin of the second switch Q2 serves as the shutdown signal output terminal and is connected to the control pin of the first switch Q1.

[0031] After receiving the reset signal RESET from the reset signal input terminal, the reset signal holding circuit 200 triggers the third switch Q3 to turn on. After the third switch Q3 turns on, it triggers the second switch Q2 to turn on, thereby pulling down the potential of the base of the first switch Q1 and turning off the first switch Q1.

[0032] Among them, Figure 2 In the long-term reset circuit of the switching power supply, the second switch Q2 in the reset signal holding circuit 200 is an NPN transistor, and the third switch Q3 is a PNP transistor. Alternatively, the second switch Q2 and the third switch Q3 in the reset signal holding circuit 200 can be a combination of N-type MOSFETs and P-type MOSFETs, or a mixture of transistors and MOSFETs.

[0033] In addition, the reset signal holding circuit 200 can also employ Figure 4 The reset signal holding circuit 200 implements its function in the following way: it includes a reset signal input terminal, a turn-off signal output terminal, a second resistor R2, a second capacitor C2, and a thyristor Q4. The reset signal input terminal is connected to one end of the second resistor R2, one end of the second capacitor C2, and the control electrode of the thyristor Q4, respectively. The other end of the second resistor R2, the other end of the second capacitor C2, and the cathode of the thyristor Q4 are grounded. The anode of the thyristor Q4 serves as the turn-off signal output terminal and is connected to the control pin of the first switching transistor Q1.

[0034] After receiving the reset signal RESET from the reset signal input terminal, the reset signal holding circuit 200 triggers the thyristor Q4 to turn on, pulling down the potential of the base of the first switching transistor Q1, thereby turning off the first switching transistor Q1.

[0035] Reference Figure 3 and Figure 4The power supply and energy storage circuit 300 includes a first capacitor C1 and a first resistor R1. One end of the first capacitor C1 and one end of the first resistor R1 are both connected to the cathode of the first diode D1. The other end of the first capacitor C1 is grounded, and the other end of the first resistor R1 is connected to the control pin of the first switching transistor Q1.

[0036] When the first switch Q1 is turned on, the transformer T1 supplies power to the chip M1 through the first diode D1 and the first switch Q1. After receiving the reset signal RESET, the reset signal holding circuit 200 outputs a turn-off signal to the first switch Q1, causing the first switch Q1 to turn off and cutting off the power supply to the power pin of the chip M1. After the chip M1 stops working, the power supply to the transformer T1 is also cut off accordingly. Since the first capacitor C1 has been fully charged when the first switch Q1 is turned on, the first capacitor C1 discharges through the first resistor R1 and the reset signal holding circuit 200 after the first switch Q1 is turned off. When the first capacitor C1 discharges to a certain extent, the discharge current of the first capacitor C1 is small and insufficient to maintain the power supply. Figure 3 The second switch Q2 and the third switch Q3 in the middle are either not conducting or insufficient to maintain Figure 4 When the thyristor Q4 is turned on, the reset signal holding circuit 200 stops outputting a turn-off signal to the first switch Q1, and the first switch Q1 is turned on again, thus resetting the chip M1. The discharge current can be adjusted by changing the values ​​of the first capacitor C1 and the first resistor R1, thereby adjusting the reset time. Choosing appropriate parameters allows the reset time to meet the requirements for long-term resets on the order of seconds.

[0037] Reference Figure 3 and Figure 5 The long-term reset circuit of the switching power supply also includes a reset signal filtering circuit 400. The reset signal filtering circuit 400 includes a third resistor R3 and a third capacitor C3. One end of the third resistor R3 is used to receive the reset signal, and the other end of the third resistor R3 is connected to one end of the third capacitor C3. The other end of the third capacitor C3 is grounded. The other end of the third resistor R3 and one end of the third capacitor C3 are also connected to the reset signal input terminal, i.e., the connection point of the second resistor R2 and the second capacitor C2. The reset signal filtering circuit 400 can filter out ripple signals in the reset signal and reduce interference.

[0038] In addition, the long-term reset circuit of the switching power supply also includes a reset signal isolation circuit. The other end of the third resistor R3 and one end of the third capacitor C3 are connected to the reset signal input terminal through the reset signal isolation circuit. If the reset signal RESET comes from the secondary winding of transformer T1, a reset signal isolation circuit is required to avoid interference between the primary and secondary windings. Figure 3 and Figure 5The reset signal isolation circuits are not shown in the diagrams, but this does not affect the understanding of the invention. The reset signal isolation circuit can use relay isolation, optocoupler isolation, or other methods of isolation, which will not be elaborated here.

[0039] Reference Figure 3 and Figure 5 The long-term reset circuit of the switching power supply also includes a reset start-up auxiliary circuit 500. The reset start-up auxiliary circuit 500 includes an auxiliary power supply terminal BUS, a fourth resistor R4 and a fourth capacitor C4. The auxiliary power supply terminal BUS is connected to one end of the fourth resistor R4. The other end of the fourth resistor R4 is connected to one end of the fourth capacitor C4, the power supply pin of the chip M1 and the output terminal of the power supply switch circuit 100, respectively. The other end of the fourth capacitor C4 is grounded.

[0040] The reset startup auxiliary circuit 500 is set up so that when the first switch Q1 is turned on again, the auxiliary power supply terminal BUS charges the fourth capacitor C4 through the fourth resistor R4, thereby increasing the voltage of the power supply pin of chip M1 and enabling chip M1 to start up again.

[0041] Reference Figure 3 and Figure 5 In the long-term reset circuit of the switching power supply, the reset start-up auxiliary circuit 500 also includes a second diode D2, the other end of the fourth resistor R4 is also connected to the anode of the second diode D2, and the cathode of the second diode D2 is connected to the reset signal sustaining circuit 200.

[0042] By setting a second diode D2, when the first switch Q1 is turned off, the auxiliary power supply terminal BUS and the fourth capacitor C4 can be discharged through the second diode D2 and the reset signal maintenance circuit 200, thus preventing the fourth capacitor C4 from being in a fully charged state.

[0043] Secondly, embodiments of the present invention provide a printed circuit board including a long-term reset circuit for a switching power supply according to the first aspect of the present invention. After receiving a reset signal, the reset signal sustaining circuit 200 outputs a shutdown signal to the power supply switching circuit 100, causing the power supply switching circuit 100 to shut down and cut off the power supply to the chip's power pins. Then, the power supply energy storage circuit 300 discharges through the reset signal sustaining circuit 200. After the power supply energy storage circuit 300 discharges, the reset signal sustaining circuit 200 stops outputting the shutdown signal, and the power supply switching circuit 100 is reconnected to supply power to the chip's power pins. This reset circuit has simple reset control and a concise structure, does not require a separate auxiliary power supply, and does not require adding a switch to the main power output circuit, thus reducing the board area and lowering costs.

[0044] Thirdly, embodiments of the present invention provide an electronic device, including a long-term reset circuit of a switching power supply according to the first aspect of the present invention, or a printed circuit board according to the second aspect of the present invention. After receiving a reset signal, the reset signal sustaining circuit 200 outputs a shutdown signal to the power supply switching circuit 100, causing the power supply switching circuit 100 to shut down and cut off the power supply to the chip's power pins. Then, the power supply energy storage circuit 300 discharges through the reset signal sustaining circuit 200. After the power supply energy storage circuit 300 discharges, the reset signal sustaining circuit 200 stops outputting the shutdown signal, and the power supply switching circuit 100 is reconnected to supply power to the chip's power pins. This reset circuit has simple reset control and a concise structure, does not require a separate auxiliary power supply, and does not require adding a switch to the main power output circuit, thus reducing board area and lowering costs.

[0045] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A long-time reset circuit for a switching power supply, characterized in that, include: A power supply switching circuit is provided, wherein the input terminal of the power supply switching circuit is connected to the power input terminal, and the output terminal of the power supply switching circuit is connected to the power supply pin of the chip; the power supply switching circuit includes a first switching transistor and a first diode, wherein the anode of the first diode is connected to the power input terminal, the cathode of the first diode is connected to one switching pin of the first switching transistor, and the other switching pin of the first switching transistor is connected to the power supply pin of the chip. A reset signal sustaining circuit is provided, wherein the control pin of the first switching transistor is connected to the reset signal sustaining circuit; the reset signal sustaining circuit is used to output a turn-off signal to the control pin of the first switching transistor when a reset signal is received. The power supply and energy storage circuit includes a first capacitor and a first resistor. One end of the first capacitor and one end of the first resistor are both connected to the cathode of the first diode. The other end of the first capacitor is grounded, and the other end of the first resistor is connected to the control pin of the first switching transistor. The first capacitor is used to discharge the reset signal sustaining circuit when the first switching transistor is turned off, so that the reset signal sustaining circuit stops outputting the turn-off signal after the first capacitor discharges.

2. The long-time reset circuit for a switching power supply according to claim 1, characterized in that, The reset signal sustaining circuit includes a reset signal input terminal, a shutdown signal output terminal, a second switch transistor, a third switch transistor, a second resistor, and a second capacitor. The reset signal input terminal is connected to one end of the second resistor, one end of the second capacitor, one switch pin of the second switch transistor, and the control pin of the third switch transistor. The other end of the second resistor, the other end of the second capacitor, and one switch pin of the third switch transistor are grounded. The other switch pin of the third switch transistor is connected to the control pin of the second switch transistor. The other switch pin of the second switch transistor serves as the shutdown signal output terminal and is connected to the control pin of the first switch transistor.

3. The long-time reset circuit for a switching power supply according to claim 1, characterized in that, The reset signal sustaining circuit includes a reset signal input terminal, a shutdown signal output terminal, a second resistor, a second capacitor, and a thyristor. The reset signal input terminal is connected to one end of the second resistor, one end of the second capacitor, and the control electrode of the thyristor. The other end of the second resistor, the other end of the second capacitor, and the cathode of the thyristor are grounded. The anode of the thyristor serves as the shutdown signal output terminal and is connected to the control pin of the first switching transistor.

4. A long-time reset circuit for a switching power supply according to claim 2 or 3, characterized in that, It also includes a reset signal filtering circuit, which includes a third resistor and a third capacitor. One end of the third resistor is used to receive the reset signal, and the other end of the third resistor is connected to one end of the third capacitor. The other end of the third capacitor is grounded, and the other end of the third resistor and one end of the third capacitor are also connected to the reset signal input terminal.

5. The long-time reset circuit for a switching power supply according to claim 4, characterized in that, It also includes a reset signal isolation circuit, wherein the other end of the third resistor and one end of the third capacitor are connected to the reset signal input terminal through the reset signal isolation circuit.

6. The long-time reset circuit for a switching power supply according to claim 1, characterized in that, It also includes a reset and start-up auxiliary circuit, which includes an auxiliary power supply terminal, a fourth resistor and a fourth capacitor. The auxiliary power supply terminal is connected to one end of the fourth resistor, and the other end of the fourth resistor is connected to one end of the fourth capacitor, the power supply pin of the chip and the output terminal of the power supply switch circuit. The other end of the fourth capacitor is grounded.

7. The long-time reset circuit for a switching power supply according to claim 6, characterized in that, The reset start-up auxiliary circuit also includes a second diode, and the other end of the fourth resistor is connected to the anode of the second diode, while the cathode of the second diode is connected to the reset signal sustaining circuit.

8. A printed circuit board, characterized in that, Includes the long-time reset circuit of the switching power supply as described in any one of claims 1 to 7.

9. An electronic device, characterized in that, It includes a long-time reset circuit for a switching power supply as described in any one of claims 1 to 7, or includes a printed circuit board as described in claim 8.

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