Overcurrent protection circuit
Overcurrent protection is achieved through switching components and control circuits, which solves the problem that power supply cannot be cut off quickly when overcurrent at the power input, protects components and automatically restores power supply, achieving safe and reliable operation of the circuit.
Patent Information
- Application Number
- CN202422459439.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-11
- Publication Date
- 2025-08-19
- Estimated Expiration
- 2034-10-11
AI Technical Summary
In the prior art, when the power input end is overcurrent, the supply of the input power to the rear-stage circuit cannot be quickly cut off, resulting in the risk of component damage, and the power supply cannot be automatically restored after normal recovery.
Switching elements Q1 and Q2 and switch control circuit are adopted to control the conduction and shutdown of the switching elements through voltage difference to realize overcurrent protection, avoid fuse blowing, and automatically restore power supply.
When the power supply is overcurrent, it quickly isolates the input power supply from the subsequent circuit, protects the components from being damaged, and automatically restores the power supply after the current returns to normal to ensure the normal operation of the circuit.
Smart Images
Figure CN223246272U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to an overcurrent protection circuit. Background Art
[0002] When an overcurrent occurs at the power input, it will have a certain impact on the components of the entire circuit, and may even cause the power components to burn out due to the high power, causing a risk accident.
[0003] To address this issue, overcurrent protection is required on the input power supply side. When an overcurrent condition occurs at the power input, the input power supply to the downstream circuitry is cut off to prevent any impact on the downstream circuitry. The most common solution in the prior art is to install a fuse circuit at the power input. When the input current at the power input is too high, the fuse blows, thereby isolating the input power from the downstream circuitry. Summary of the Invention
[0004] The technical problem to be solved by the utility model is to provide an overcurrent protection circuit, which can quickly cut off the supply of input power to the subsequent circuit when the input power is overcurrent, and can automatically restore the supply of input power to the subsequent circuit after the current of the input power returns to normal.
[0005] An overcurrent protection circuit according to an embodiment of the present invention includes a power input terminal Vin, a power output terminal Vout, a switching element Q1, a switching element Q2, a switch control circuit, and a resistor R5; the power input terminal Vin is used to connect to a power supply, and the power output terminal Vout is used to connect to a power input terminal of a power receiving system; a first conductive end of the switching element Q1 is connected to the power input terminal Vin, a second conductive end of the switching element Q1 is connected to a first end of a resistor R5, and a second end of the resistor R5 is connected to the power output terminal Vout; a first conductive end of the switching element Q2 is connected to a common ground between the first conductive end of the switching element Q1 and the power input terminal Vin. The second conducting end of the switching element Q2 is connected to the input end of the switching control circuit, the controlled end of the switching element Q2 is connected to the common connection of the second end of the resistor R5 and the power output end Vout, and the output end of the switching control circuit is connected to the controlled end of the switching element Q1; the switching element Q2 is configured to be turned off when the voltage difference between the first conducting end and the controlled end of the switching element Q2 is less than a predetermined turn-on voltage threshold, and to cause the switching control circuit to control the switching element Q1 to be turned on; and to be turned on when the voltage difference between the first conducting end and the controlled end of the switching element Q2 is greater than or equal to the predetermined turn-on voltage threshold, and to cause the switching control circuit to control the switching element Q1 to be turned off.
[0006] The utility model has at least the following technical effects:
[0007] 1. The overcurrent protection circuit of the embodiment of the present invention does not require a fuse. Instead, it uses a switching element to isolate the input power terminal from the subsequent circuit when the input current overcurrent occurs. That is, when the current at the power input terminal is too large, the switching element is disconnected, thereby isolating the input power terminal from the subsequent circuit, thereby cutting off the supply of input power to the subsequent circuit and protecting the components of the subsequent circuit from damage.
[0008] 2. After the current of the input power supply returns to normal, the switch element of the overcurrent protection circuit of the embodiment of the utility model can automatically resume conduction, thereby restoring the power supply of the input power supply to the subsequent circuit, allowing the subsequent circuit to resume normal operation. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 The figure shows a circuit principle diagram of an overcurrent protection circuit according to an embodiment of the present utility model. DETAILED DESCRIPTION
[0010] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0011] Please refer to Figure 1 The overcurrent protection circuit according to an embodiment of the present invention includes a power input terminal Vin, a power output terminal Vout, a switch element Q1, a switch element Q2, a switch control circuit 1, and a resistor R5.
[0012] The power input terminal Vin is used to connect to a power supply, and the power output terminal Vout is used to connect to a power input terminal of a power receiving system (ie, a subsequent circuit).
[0013] A first conducting end of the switch element Q1 is connected to the power input terminal Vin, a second conducting end of the switch element Q1 is connected to a first end of the resistor R5, and a second end of the resistor R5 is connected to the power output terminal Vout.
[0014] The first conduction terminal of the switching element Q2 is connected to the common point of the first conduction terminal of the switching element Q1 and the power input terminal Vin. The second conduction terminal of the switching element Q2 is connected to the input terminal of the switch control circuit 1. The controlled terminal of the switching element Q2 is connected to the common point of the second end of the resistor R5 and the power output terminal Vout. The output terminal of the switch control circuit is connected to the controlled terminal of the switching element Q1. The switching element Q2 is configured to be turned off when the voltage difference between the first conduction terminal and the controlled terminal of the switching element Q2 is less than a predetermined turn-on voltage threshold, causing the switch control circuit 1 to control the switching element Q1 to turn on. The switching element Q2 is configured to be turned on when the voltage difference between the first conduction terminal and the controlled terminal of the switching element Q2 is greater than or equal to the predetermined turn-on voltage threshold, causing the switch control circuit 1 to control the switching element Q1 to turn off.
[0015] In this embodiment, the switching element Q1 is a PMOS transistor, the gate of which is the controlled terminal, the source of which is the first conductive terminal, and the drain of which is the second conductive terminal. The switching element Q2 is a PNP transistor, the base of which is the controlled terminal, the emitter of which is the first conductive terminal, and the collector of which is the second conductive terminal.
[0016] Preferably, the overcurrent protection circuit of this embodiment includes a voltage regulator diode D1, the anode and cathode of which are connected to the gate and source of the PMOS transistor, respectively, to prevent the voltage between the gate and source of the PMOS transistor from exceeding a protection voltage value, thereby damaging the field-effect transistor.
[0017] In this embodiment, the switch control circuit 1 includes a voltage divider circuit 10 , a first switch circuit 11 and a second switch circuit 12 .
[0018] The input end of the voltage divider circuit 10 constitutes the input end of the switch control circuit 1, and the output end of the voltage divider circuit 10 is connected to the controlled end of the first switch circuit 11. Specifically, the voltage divider circuit 10 includes a resistor R3 and a resistor R2, with resistors R3 and R2 connected in series. The first end of resistor R3 constitutes the input end of the voltage divider circuit 10, and the common point between the second end of resistor R3 and the first end of resistor R2 constitutes the output end of the voltage divider circuit 10. The second end of resistor R2 is grounded.
[0019] The first conducting terminal of the first switch circuit 11 is connected to the power supply circuit, and the second conducting terminal of the first switch circuit 11 is grounded. The first switch circuit 11 is configured to be turned off when the switch element Q2 is turned off, and to be turned on when the switch element Q2 is turned on. The first conducting terminal of the second switch circuit 12 is connected to the controlled terminal of the switch element Q1, and the second conducting terminal of the second switch circuit 12 is grounded. The controlled terminal of the second switch circuit 12 is connected to the common point between the first conducting terminal of the first switch circuit and the power supply circuit. The second switch circuit 12 is configured to be turned on when the first switch circuit 11 is turned off, thereby turning on the switch element Q1, and to be turned off when the first switch circuit 11 is turned on, thereby turning off the switch element Q1.
[0020] In this embodiment, the first switch circuit 11 includes an NPN transistor Q3, the base, collector, and emitter of which respectively constitute the controlled terminal, the first conducting terminal, and the second conducting terminal of the first switch circuit 11. The power supply circuit includes a resistor R1, the first end of which is connected to the power input terminal Vin, and the second end of which is connected to the collector of the NPN transistor Q3. The second switch circuit 12 includes an NPN transistor Q4 and a resistor R4, the two ends of which are respectively connected to the base and emitter of the NPN transistor Q4, and the base, collector, and emitter of the NPN transistor Q4 respectively constitute the controlled terminal, the first conducting terminal, and the second conducting terminal of the second switch circuit 12.
[0021] When there's no overcurrent at the power input Vin, point D (the collector of NPN transistor Q3) is at a high level, and the voltage at point E (the base of NPN transistor Q4) is greater than the turn-on voltage of NPN transistor Q4. Therefore, NPN transistor Q4 is in the on state, lowering the voltage at the controlled terminal of switch element Q1 (the gate voltage of the PMOS transistor). Since point A (the source of the PMOS transistor) is at a high level, the PMOS transistor is in the on state. The input current at the power input Vin is output to the power output Vout through the PMOS transistor and resistor R5. The selection of resistor R5 should be determined based on the overcurrent threshold. Since there is no overcurrent at this time, the sum of the voltage drops across the PMOS transistor and resistor R5, i.e., the voltage drop between points A and B (i.e., the voltage drop between the emitter and base of NPN transistor Q2), is less than the turn-on voltage threshold of NPN transistor Q2. Therefore, NPN transistor Q2 is in the off state, and NPN transistor Q3 is also turned off. At this point, the output current of the power input terminal Vin is output to the power output terminal Vout through the switch element Q1 and resistor R5, indicating that the circuit is functioning normally.
[0022] When an overcurrent occurs at the power input terminal Vin, the sum of the voltage drops of the PMOS tube and the resistor R5, that is, the voltage drop between points A and B, is equal to or greater than the turn-on voltage threshold of the NPN transistor Q2. Therefore, the NPN transistor Q2 is in the on state. The selection of resistors R2 and R3 satisfies that when the NPN transistor Q2 is in the on state, the voltage at point C (the base of the NPN transistor Q3) is greater than the turn-on voltage threshold of the NPN transistor Q3. Therefore, the NPN transistor Q3 is in the on state. At this time, point D is pulled down to a low level, that is, point E is a low level, the NPN transistor Q4 is in the off state, and thus the PMOS tube is also in the off state. The input current of the power input terminal Vin cannot be transmitted to the resistor R5 through the switching element Q1, thereby cutting off the input side circuit.
[0023] When the input current of the power input terminal Vin returns to normal, the NPN transistor Q2 is turned off, the NPN transistor Q4 is turned on, the switch element Q1 is turned on, and the circuit returns to normal operation.
Claims
1. An overcurrent protection circuit, characterized in that: It includes a power input terminal Vin, a power output terminal Vout, a switching element Q1, a switching element Q2, a switch control circuit and a resistor R5; The power input terminal Vin is used to connect to the power supply, and the power output terminal Vout is used to connect to the power input terminal of the power receiving system; The first conducting end of the switch element Q1 is connected to the power input terminal Vin, the second conducting end of the switch element Q1 is connected to the first end of the resistor R5, and the second end of the resistor R5 is connected to the power output terminal Vout; A first conducting end of the switching element Q2 is connected to a common point between the first conducting end of the switching element Q1 and the power input terminal Vin, a second conducting end of the switching element Q2 is connected to an input terminal of a switch control circuit, a controlled end of the switching element Q2 is connected to a common point between the second end of the resistor R5 and the power output terminal Vout, and an output terminal of the switch control circuit is connected to the controlled end of the switching element Q1; The switching element Q2 is used to be turned off when the voltage difference between the first conduction end and the controlled end of the switching element Q2 is less than a predetermined turn-on voltage threshold, and to enable the switching control circuit to control the switching element Q1 to be turned on; and to be turned on when the voltage difference between the first conduction end and the controlled end of the switching element Q2 is greater than or equal to the predetermined turn-on voltage threshold, and to enable the switching control circuit to control the switching element Q1 to be turned off.
2. The overcurrent protection circuit according to claim 1, characterized in that: The switch control circuit includes a voltage divider circuit, a first switch circuit and a second switch circuit; The input end of the voltage divider circuit constitutes the input end of the switch control circuit, and the output end of the voltage divider circuit is connected to the controlled end of the first switch circuit; A first conducting end of the first switch circuit is connected to the power supply circuit, a second conducting end of the first switch circuit is grounded, and the first switch circuit is configured to be turned off when the switch element Q2 is turned off, and turned on when the switch element Q2 is turned on; The first conduction end of the second switch circuit is connected to the controlled end of the switch element Q1, the second conduction end of the second switch circuit is grounded, and the controlled end of the second switch circuit is connected to the common point of the first conduction end of the first switch circuit and the power supply circuit. The second switch circuit is used to turn on when the first switch circuit is turned off and turn on the switch element Q1, and to turn off when the first switch circuit is turned on and turn off the switch element Q1.
3. The overcurrent protection circuit according to claim 2, wherein: The first switch circuit includes an NPN transistor Q3, wherein the base, collector and emitter of the NPN transistor Q3 respectively constitute a controlled end, a first conducting end and a second conducting end of the first switch circuit; The power supply circuit includes a resistor R1 , a first end of the resistor R1 is connected to a power input terminal Vin, and a second end of the resistor R1 is connected to a collector of an NPN transistor Q3 .
4. The overcurrent protection circuit according to claim 2, wherein: The second switching circuit includes an NPN transistor Q4 and a resistor R4. The two ends of the resistor R4 are respectively connected to the base and emitter of the NPN transistor Q4. The base, collector and emitter of the NPN transistor Q4 respectively constitute the controlled end, the first conduction end and the second conduction end of the second switching circuit.
5. The overcurrent protection circuit according to claim 2, wherein: The voltage divider circuit includes a resistor R3 and a resistor R2, and the resistor R3 is connected in series with the resistor R2; The first end of the resistor R3 constitutes the input end of the voltage divider circuit, the common connection point of the second end of the resistor R3 and the first end of the resistor R2 constitutes the output end of the voltage divider circuit, and the second end of the resistor R2 is grounded.
6. The overcurrent protection circuit according to any one of claims 1 to 5, characterized in that: The switch element Q1 is a PMOS tube, the gate of the PMOS tube is a controlled terminal, the source of the PMOS tube is a first conducting terminal, and the drain of the PMOS tube is a second conducting terminal.
7. The overcurrent protection circuit according to claim 6, characterized in that: The overcurrent protection circuit includes a voltage regulator tube D1, and the anode and cathode of the voltage regulator tube D1 are respectively connected to the gate and source of the PMOS tube.
8. The overcurrent protection circuit according to any one of claims 1 to 5, characterized in that: The switching element Q2 is a PNP transistor, the base of the PNP transistor is the controlled end, the emitter of the PNP transistor is the first conduction end, and the collector of the PNP transistor is the second conduction end.