Power failure protection circuit and gateway
By combining voltage detection circuit and switching circuit, the problems of high cost, large size and complicated wiring of power-off protection circuits in small electronic products are solved, and the effect of data preservation is achieved even when power is lost.
Patent Information
- Application Number
- CN202420564644.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-21
- Publication Date
- 2025-03-07
- Estimated Expiration
- 2034-03-21
AI Technical Summary
Existing power-down protection circuits are expensive, bulky, and have complex wiring in small electronic products. They cannot handle large currents, which means that the products cannot save data in time when power is lost.
The system employs a combination of voltage detection circuit, switching circuit, and capacitor circuit. The voltage detection circuit detects whether the power supply has failed, the switching circuit disconnects when a power failure is detected, and the capacitor circuit continues to supply power to extend the product's operating time.
It enables data to be retained even when power is lost. The circuit structure is simple, low-cost, and occupies little space, making it suitable for small electronic products.
Smart Images
Figure CN222582048U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of electronic products, and more specifically to a power-off protection circuit and a gateway. Background Art
[0002] Electronic products may be powered off and shut down instantly due to sudden disconnection of external power or failure of the power supply of the circuit board during use. Since the power-off time is too short, the last data and error information cannot be kept in time. In order to solve this problem, a power-off protection circuit is set in the product. At present, the commonly used power-off protection circuit mainly uses PWM control chips or power management chips for power-off detection and protection. However, due to the relatively high prices of PWM control chips and power management chips, for small electronic products, such as home gateway products, additional high costs are added. In addition, PWM control chips and power management chips are large in size and occupy more space. The corresponding hardware configuration also occupies a large space, which is more troublesome for PCB wiring. In addition, the current passed by PWM control chips and power management chips is uncontrollable and cannot pass large currents. As the passing current increases, the chip price usually increases and the volume also increases accordingly. Utility Model Content
[0003] The technical problem to be solved by the utility model is to provide a power-off protection circuit and a gateway that can pass large current and have low cost and small size, while achieving the purpose of continuing to supply power to the product when power failure of the power supply is detected.
[0004] In order to solve the above technical problems, according to one aspect of the utility model, a power-off protection circuit is provided, comprising:
[0005] A voltage detection circuit is connected to the power supply and is used to detect whether the power supply voltage is less than a preset threshold value to detect whether power is off;
[0006] A capacitor circuit, used for supplying power when the power supply fails;
[0007] The switch circuit is connected between the voltage detection circuit and the capacitor circuit, and is used to be turned on when the power supply voltage is not less than a preset threshold value, so that the power supply can supply power, and to be turned off when the power supply fails so that the capacitor circuit can supply power.
[0008] Its further technical solution is: the switching circuit includes a first switching tube, a second switching tube and a first resistance voltage divider circuit, wherein the control end of the first switching tube is connected to the output end of the voltage detection circuit, the input end of the first switching tube is connected to an input end of the first resistance voltage divider circuit, the output end of the first switching tube is grounded, the other input end of the first resistance voltage divider circuit is connected to the power supply and the input end of the second switching tube, and the control end and the output end of the second switching tube are respectively connected to the output end of the first resistance voltage divider circuit and the input end of the capacitor circuit.
[0009] Its further technical solution is: the first resistor voltage-dividing circuit includes a first voltage-dividing resistor and a second voltage-dividing resistor, one end of the first voltage-dividing resistor is connected to one end of the second voltage-dividing resistor and the control end of the second switch tube, the other end of the first voltage-dividing resistor is connected to the input end of the second switch tube and the power supply, and the other end of the second voltage-dividing resistor is connected to the input end of the first switch tube.
[0010] Its further technical solution is: the first switch tube is an NPN transistor, and the second switch tube is a PMOS tube, wherein the collector, emitter and base of the NPN transistor serve as the input end, output end and control end of the first switch tube respectively, and the source, drain and gate of the PMOS tube serve as the input end, output end and control end of the second switch tube respectively.
[0011] Its further technical solution is: the switching circuit also includes a first current limiting resistor and a second current limiting resistor, the first current limiting resistor is connected between the control end of the first switching tube and the output end of the voltage detection circuit, and the second current limiting resistor is connected between the control end of the second switching tube and the output end of the first resistance voltage divider circuit.
[0012] Its further technical solution is: the switching circuit also includes a bypass resistor, a first capacitor, a second capacitor and a third current limiting resistor, the bypass resistor is connected between the control end and the output end of the first switching tube, the second capacitor and the third current limiting resistor are connected in series and connected between the output end of the second switching tube and the output end of the first resistance divider circuit, one end of the first capacitor is connected to the power supply and the input end of the second switching tube, and the other end is connected to the output end of the first resistance divider circuit.
[0013] Its further technical solution is: the voltage detection circuit includes a voltage detection chip and a second resistor voltage divider circuit, the power supply is connected to the power input pin of the voltage detection chip through the second resistor voltage divider circuit to provide the voltage detection chip with a power supply voltage for detection, and the output pin of the voltage detection chip is connected to the switching circuit.
[0014] Its further technical solution is: the second resistor voltage-divider circuit includes a third voltage-divider resistor, a fourth voltage-divider resistor and a fifth voltage-divider resistor, wherein one end of the fourth voltage-divider resistor is connected to one end of the third voltage-divider resistor and the power input pin of the voltage detection chip, the other end of the fourth voltage-divider resistor is connected to one end of the fifth voltage-divider resistor, and the other ends of the third voltage-divider resistor and the fifth voltage-divider resistor are respectively connected to the power supply and the ground.
[0015] A further technical solution is as follows: the capacitor circuit comprises a third capacitor and a fourth capacitor, and the third capacitor and the fourth capacitor are connected in parallel with one end connected to the switch circuit and the other end grounded.
[0016] In order to solve the above technical problem, the utility model also provides a gateway, which includes the above power-off protection circuit.
[0017] Compared with the prior art, the power-off protection circuit of the utility model is provided with a voltage detection circuit for detecting whether the power supply is powered off and a capacitor circuit for supplying power when the power supply is powered off, and a switch circuit is also connected between the voltage detection circuit and the capacitor circuit. When the voltage detection circuit detects that the power supply voltage is greater than or equal to a preset threshold value, the power supply is normal, the switch circuit is turned on, the power supply is supplied, and the capacitor circuit can also be charged at the same time. The capacitor circuit stores power supply energy, and when it is detected that the power supply voltage is less than the preset threshold value, the switch circuit is closed and the capacitor circuit is supplied, that is, when the power supply is powered off, the capacitor circuit is supplied, so that the product applied by the power-off protection circuit can continue to run for a period of time to save operation data, etc. It can be seen that the power-off protection circuit of the utility model can detect whether the power supply is powered off, and when the power is not powered off, the normal power supply of the power supply and the charging of the capacitor circuit can still be maintained through the switch circuit. When the power is off, the switch circuit is disconnected, and the capacitor circuit is supplied with power to give the internal system of the product a certain time to save data, etc., and the switch circuit can pass a large current, the overall circuit structure is relatively simple, the volume is small, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 The utility model is a circuit block diagram of a specific embodiment of the power-off protection circuit.
[0019] Figure 2 The utility model is a circuit diagram of a specific embodiment of the power-off protection circuit. DETAILED DESCRIPTION
[0020] In order to enable ordinary technicians in the field to more clearly understand the purpose, technical solutions and advantages of the utility model, the utility model is further explained below in conjunction with the accompanying drawings and embodiments.
[0021] Reference Figure 1 to Figure 2 , Figure 1 to Figure 2A specific embodiment of the power-off protection circuit of the utility model is shown. In the embodiment shown in the accompanying drawings, the power-off protection circuit includes a voltage detection circuit 11, a switch circuit 12 and a capacitor circuit 13, wherein the voltage detection circuit 11 is connected to the power supply VCC, and is used to detect whether the power supply voltage is less than a preset threshold value to detect whether there is a power failure; the capacitor circuit 13 is used to supply power when the power supply VCC is powered off; the switch circuit 12 is connected between the voltage detection circuit 11 and the capacitor circuit 13, and is used to be turned on when the power supply voltage is not less than a preset threshold value, and the power supply VCC supplies power, and is turned off when the power supply VCC is powered off so that the capacitor circuit 13 is powered. Preferably, in this embodiment, the power supply VCC is a 5V power supply. Based on the above design, the power-off protection circuit of the utility model can detect whether the power supply VCC is powered off through the voltage detection circuit 11. When the power is not off, the switch circuit 12 is turned on. The normal power supply of the power supply VCC and the charging of the capacitor circuit 13 can still be maintained through the switch circuit 12. When the power is off, the switch circuit 12 is disconnected, and the capacitor circuit 13 discharges to the outside to supply power, so that the product can continue to run for a period of time when the power is off to save operating data, etc., and the switch circuit 12 can pass a large current. The overall circuit structure of the power-off protection circuit is also relatively simple, and the wiring is convenient. When applied to products, it occupies a small volume and has a low cost.
[0022] In some embodiments, the voltage detection circuit 11 includes a voltage detection chip U661 and a second resistor voltage divider circuit 111. Preferably, in this embodiment, the model of the voltage detection chip U661 is PT7M7809RTE, and the power supply VCC is connected to the power input pin of the voltage detection chip U661 through the second resistor voltage divider circuit 111 to provide the voltage detection chip U661 with a power supply voltage for detection, and the output pin of the voltage detection chip U661 is connected to the switch circuit 12. Based on the above design, the voltage detection chip U661 is used for power-off detection, the circuit construction is relatively simple, and the voltage detection chip U661 is cheap, small in size, and occupies less space.
[0023] Specifically, Figure 2As shown, the second resistor voltage-divider circuit 111 includes a third voltage-divider resistor R2208, a fourth voltage-divider resistor R2210 and a fifth voltage-divider resistor R2211, wherein one end of the fourth voltage-divider resistor R2210 is connected to one end of the third voltage-divider resistor R2208 and a power input pin of the voltage detection chip U661, the other end of the fourth voltage-divider resistor R2210 is connected to one end of the fifth voltage-divider resistor R2211, and the other ends of the third voltage-divider resistor R2208 and the fifth voltage-divider resistor R2211 are respectively connected to the power supply VCC and the ground. In this embodiment, the resistance values of the third voltage-dividing resistor R2208, the fourth voltage-dividing resistor R2210 and the fifth voltage-dividing resistor R2211 are all 200Ω. It can be understood that the size of the preset threshold can be set according to the resistance values of the three voltage-dividing resistors and the size of the power supply VCC. Considering power supply fluctuations, etc., it can be preferably set to 2.63V, that is, when it is detected that the voltage input to the voltage detection chip U661 is greater than 4.208V, it is considered that the power supply VCC is supplying normally. At this time, the output pin of the voltage detection chip U661 outputs a high level, otherwise, it outputs a low level.
[0024] In some embodiments, the switch circuit 12 includes a first switch tube Q101, a second switch tube Q117 and a first resistor voltage divider circuit 123, wherein the control end of the first switch tube Q101 is connected to the output end of the voltage detection circuit 11, the input end of the first switch tube Q101 is connected to an input end of the first resistor voltage divider circuit 123, the output end of the first switch tube Q101 is grounded, the other input end of the first resistor voltage divider circuit 123 is connected to the power supply VCC and the input end of the second switch tube Q117, and the control end and the output end of the second switch tube Q117 are respectively connected to the output end of the first resistor voltage divider circuit 123 and the input end of the capacitor circuit 13.
[0025] Preferably, in this embodiment, the first switch tube Q101 is an NPN transistor, and the second switch tube Q117 is a PMOS tube, wherein the collector, emitter and base of the NPN transistor respectively serve as the input end, output end and control end of the first switch tube Q101, and the source, drain and gate of the PMOS tube respectively serve as the input end, output end and control end of the second switch tube Q117.
[0026] Specifically, the first resistor voltage divider circuit 123 includes a first voltage divider resistor R1873 and a second voltage divider resistor R1619, one end of the first voltage divider resistor R1873 is connected to one end of the second voltage divider resistor R1619 and the gate of the second switch tube Q117, the other end of the first voltage divider resistor R1873 is connected to the source of the second switch tube Q117 and the power supply VCC, and the other end of the second voltage divider resistor R1619 is connected to the collector of the first switch tube Q101. In this embodiment, the resistance values of the first voltage divider resistor R1873 and the second voltage divider resistor R1619 are 20KΩ and 10KΩ respectively. Based on the above design, when the output pin of the voltage detection chip U661 outputs a high level, the first switch tube Q101 is turned on, the second switch tube Q117 is also turned on, and VCC is output after passing through the second switch tube Q117 for power supply; and when the voltage detection chip U661 detects that the power supply VCC is powered off and the output pin outputs a low level, the first switch tube Q101 is turned off, the gate and source voltages of the second switch tube Q117 are the same, the second switch tube Q117 is also turned off, and the power supply VCC cannot supply power. At this time, the capacitor circuit 13 discharges to supply power.
[0027] Furthermore, in some embodiments, the switch circuit 12 further includes a first current limiting resistor R1618, a second current limiting resistor R1874, a bypass resistor R1616, a first capacitor C2946, a second capacitor C2947 and a third current limiting resistor R1875, the first current limiting resistor R1618 is connected between the base of the first switch tube Q101 and the output end of the voltage detection circuit 11, the second current limiting resistor R1874 is connected between the gate of the second switch tube Q117 and the first resistor divider circuit 123 , and the bypass resistor R1616 is connected between the base and emitter of the first switch tube Q101, the second capacitor C2947 and the third current limiting resistor R1875 are connected in series and connected between the drain of the second switch tube Q117 and the output end of the first resistor voltage divider circuit 123, one end of the first capacitor C2946 is connected to the power supply VCC and the source of the second switch tube Q117, and the other end is connected to the end of the second voltage dividing resistor R1619 connected to the first voltage dividing resistor R1873. Based on the above design, the first current limiting resistor R1618, the second current limiting resistor R1874 and the third current limiting resistor R1875 can prevent the large current from burning the switch tube, and the bypass resistor R1616 can prevent the NPN transistor from leaving the cut-off region and entering the wrong conduction state.
[0028] Continue to refer to Figure 2In the embodiment shown in the accompanying drawings, the capacitor circuit 13 includes a third capacitor C2948, a fourth capacitor C2949, a fifth capacitor C2950 and a sixth capacitor C2951. The third capacitor C2948, the fourth capacitor C2949, the fifth capacitor C2950 and the sixth capacitor C2951 are connected in parallel, one end of which is connected to the drain of the second switch tube Q117, and the other end is grounded. Preferably, in the present utility model, the third capacitor C2948 and the fourth capacitor C2949 are both large capacitors to store a large amount of charge.
[0029] In the present invention, when the power supply VCC input is normal, Figure 2 As shown, the 5V power supply is input to the voltage detection chip U661 after passing through the second resistor voltage divider circuit 111. The voltage detection chip U661 detects that the power supply voltage is higher than the preset threshold at this time, and its output pin RES outputs a high level. The first switch tube Q101 is turned on, and the power supply VCC is divided by the first voltage divider resistor R1873 and the second voltage divider resistor R1619, and VGS is about -3.4V, which meets the PMOS tube conduction condition, and the second switch tube Q117 is turned on. VCC outputs the power supply OUT after passing through the second switch tube Q117; and when 5 When the V input loses power momentarily and the voltage detection chip U661 detects that the power supply voltage is lower than the preset threshold at this time, the output pin RES outputs a low level, the NPN transistor does not conduct, and the 5V VCC current flows in a direction that does not pass through the first switch tube Q101. The gate and source voltages of the PMOS tube are the same, VGS is not lower than 0V, the PMOS tube does not conduct, and VCC cannot be powered by the PMOS tube. At this time, the third capacitor C2948 and the fourth capacitor C2949 in the capacitor circuit 13 supply power, thereby extending the data retention time of the internal system of the product.
[0030] In summary, the power-off protection circuit of the utility model can detect whether the power supply VCC is powered off when the product is powered off, and can supply power through the capacitor circuit 13 when the power is off, so that the product to which the power-off protection circuit is applied can continue to run for a period of time to save operating data, etc. When the power is not off, the switch circuit 12 works, the first switch tube Q101 and the second switch tube Q117 are turned on, and the power supply VCC can still be kept normally powered and the capacitor circuit 13 can be charged. In this process, the switch circuit 12 can pass a large current, and the power-off judgment and power supply switch are realized through the cooperation of the triode, the MOS tube and the voltage detection chip U661. The circuit structure is simple and the cost is low. The detection voltage and the preset threshold value can be adjusted independently according to the actual situation, and it is easy to use.
[0031] Understandably, the utility model also provides a gateway, which includes the power-off protection circuit described in the above embodiment. When the gateway is powered off, the power-off protection circuit can extend the data retention time of the internal system of the gateway. When the power supply is normal, the power supply VCC supplies power and the gateway works normally. Since the overall circuit structure of the power-off protection circuit is relatively simple, when it is applied to the gateway, the wiring is more convenient, the occupied volume is smaller, and the cost is also lower.
[0032] The above description is only a preferred embodiment of the utility model, and does not limit the utility model in any form. Those skilled in the art can make various equivalent changes and improvements based on the above embodiments, and all equivalent changes or modifications made within the scope of the claims should fall within the protection scope of the utility model.
Claims
1. A power-off protection circuit, characterized in that: include: A voltage detection circuit is connected to the power supply and is used to detect whether the power supply voltage is less than a preset threshold value to detect whether power is off; A capacitor circuit, used for supplying power when the power supply fails; The switch circuit is connected between the voltage detection circuit and the capacitor circuit, and is used to be turned on when the power supply voltage is not less than a preset threshold value, so that the power supply can supply power, and to be turned off when the power supply fails so that the capacitor circuit can supply power.
2. The power-off protection circuit according to claim 1, characterized in that: The switch circuit includes a first switch tube, a second switch tube and a first resistor voltage divider circuit, wherein the control end of the first switch tube is connected to the output end of the voltage detection circuit, the input end of the first switch tube is connected to an input end of the first resistor voltage divider circuit, the output end of the first switch tube is grounded, the other input end of the first resistor voltage divider circuit is connected to a power supply and the input end of the second switch tube, and the control end and the output end of the second switch tube are respectively connected to the output end of the first resistor voltage divider circuit and the input end of the capacitor circuit.
3. The power-off protection circuit according to claim 2, characterized in that: The first resistor voltage-divider circuit includes a first voltage-divider resistor and a second voltage-divider resistor, one end of the first voltage-divider resistor is connected to one end of the second voltage-divider resistor and the control end of the second switch tube, the other end of the first voltage-divider resistor is connected to the input end of the second switch tube and the power supply, and the other end of the second voltage-divider resistor is connected to the input end of the first switch tube.
4. The power-off protection circuit according to claim 2, characterized in that: The first switch tube is an NPN transistor, and the second switch tube is a PMOS tube, wherein the collector, emitter and base of the NPN transistor serve as the input end, output end and control end of the first switch tube respectively, and the source, drain and gate of the PMOS tube serve as the input end, output end and control end of the second switch tube respectively.
5. The power-off protection circuit according to claim 4, characterized in that: The switching circuit also includes a first current limiting resistor and a second current limiting resistor, the first current limiting resistor is connected between the control end of the first switching tube and the output end of the voltage detection circuit, and the second current limiting resistor is connected between the control end of the second switching tube and the output end of the first resistance voltage divider circuit.
6. The power-off protection circuit according to claim 5, characterized in that: The switching circuit also includes a bypass resistor, a first capacitor, a second capacitor and a third current limiting resistor. The bypass resistor is connected between the control end and the output end of the first switching tube. The second capacitor and the third current limiting resistor are connected in series and connected between the output end of the second switching tube and the output end of the first resistance divider circuit. One end of the first capacitor is connected to the power supply and the input end of the second switching tube, and the other end is connected to the output end of the first resistance divider circuit.
7. The power-off protection circuit according to claim 1, characterized in that: The voltage detection circuit includes a voltage detection chip and a second resistor voltage divider circuit. The power supply is connected to the power input pin of the voltage detection chip through the second resistor voltage divider circuit to provide the voltage detection chip with a power supply voltage for detection. The output pin of the voltage detection chip is connected to the switch circuit.
8. The power-off protection circuit according to claim 7, characterized in that: The second resistor voltage-divider circuit includes a third voltage-divider resistor, a fourth voltage-divider resistor and a fifth voltage-divider resistor, wherein one end of the fourth voltage-divider resistor is connected to one end of the third voltage-divider resistor and a power input pin of the voltage detection chip, the other end of the fourth voltage-divider resistor is connected to one end of the fifth voltage-divider resistor, and the other ends of the third voltage-divider resistor and the fifth voltage-divider resistor are connected to a power supply and ground, respectively.
9. The power-off protection circuit according to claim 1, characterized in that: The capacitor circuit comprises a third capacitor and a fourth capacitor. After the third capacitor and the fourth capacitor are connected in parallel, one end of the third capacitor and the fourth capacitor is connected to the switch circuit, and the other end is grounded.
10. A gateway, characterized in that: The invention comprises the power-off protection circuit as described in any one of claims 1 to 9.