An overcurrent protection circuit and electronic device

Abstract

The utility model relates to a kind of overcurrent protection circuit and electronic equipment.The overcurrent protection circuit includes: for providing power input power input terminal and for providing power output power output terminal, and current sampling unit, bias unit, first switch unit and second switch unit;Current sampling unit is connected between power input terminal and power output terminal, for generating sampling result according to the output current of power output terminal;First switch unit connects current sampling unit, for switching state to turn on or turn off according to the sampling result of current sampling unit;Bias unit connects first switch unit, for providing bias voltage for first switch unit;Second switch unit is connected between power input terminal and power output terminal, and connects first switch unit, for switching power input terminal and power output terminal to turn on or turn off according to the state of first switch unit. Through the utility model, the power consumption of current sampling circuit in the whole circuit working process can be reduced.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuit technology, and more specifically, to an overcurrent protection circuit and electronic equipment. Background Technology

[0002] During the operation of power supplies or electronic devices, when power is supplied to a load, a current sampling resistor is typically used to sample the load input current to protect the load current. If the load is a high-current load, the power consumption of the current sampling resistor will increase accordingly, resulting in a larger power rating for the current sampling resistor, requiring a larger package and PCB area. Simultaneously, increased power consumption will cause a larger temperature rise in the current sampling resistor, leading to a greater temperature drift error and a decrease in the accuracy of the current sampling resistor. Utility Model Content

[0003] The technical problem to be solved by this utility model is to provide an overcurrent protection circuit and electronic device, which addresses the above-mentioned technical defects of the prior art.

[0004] The technical solution adopted by this utility model to solve its technical problem is: to construct an overcurrent protection circuit, including: a power input terminal for providing power input and a power output terminal for providing power output, as well as a current sampling unit, a bias unit, a first switching unit and a second switching unit.

[0005] The current sampling unit is connected between the power input terminal and the power output terminal, and is used to generate sampling results based on the output current of the power output terminal.

[0006] The first switching unit is connected to the current sampling unit and is used to switch the state to turn on or off according to the sampling result of the current sampling unit.

[0007] The bias unit is connected to the first switching unit and is used to provide a bias voltage to the first switching unit;

[0008] The second switching unit is connected between the power input terminal and the power output terminal, and is also connected to the first switching unit, for switching the power input terminal and the power output terminal on or off according to the state of the first switching unit.

[0009] Preferably, in one embodiment of the overcurrent protection circuit of this utility model, the first switching unit includes a first resistor, a second resistor, and a transistor;

[0010] The first end of the first resistor is connected to the first end of the current sampling unit, and the second end of the first resistor is connected to the emitter of the transistor.

[0011] The base of the transistor is connected to the second terminal of the current sampling unit via the second resistor, and the collector of the transistor is connected to the control terminal of the second switching unit.

[0012] The emitter of the transistor is also connected to the bias unit for receiving the bias voltage.

[0013] Preferably, in one embodiment of the overcurrent protection circuit of this utility model, the bias unit includes a third resistor and a bias voltage generation circuit;

[0014] The first terminal of the bias voltage generation circuit is connected to the first terminal of the third resistor and is used to output the bias voltage.

[0015] The second end of the third resistor is connected to the emitter of the transistor, and the second end of the bias voltage generation circuit is connected to the power supply output.

[0016] Preferably, in one embodiment of the overcurrent protection circuit of this utility model, the bias unit further includes a fourth resistor and a voltage regulator circuit;

[0017] The first terminal of the bias voltage generating circuit is connected to the first terminal of the fourth resistor, the second terminal of the fourth resistor is connected to the first terminal of the third resistor and the first terminal of the voltage regulator circuit, and the second terminal of the voltage regulator circuit is connected to the second terminal of the bias voltage generating circuit.

[0018] Preferably, in one embodiment of the overcurrent protection circuit of this utility model, the voltage regulator circuit includes a Zener diode;

[0019] The first end of the Zener diode is connected to the power output terminal, and the second end of the Zener diode is connected to the first end of the third resistor.

[0020] Preferably, in one embodiment of the overcurrent protection circuit of this utility model, the bias voltage generation circuit includes a DC-DC conversion module;

[0021] The input terminal of the DC-DC conversion module is used to input a power supply voltage, and the output terminal of the DC-DC conversion module is the first terminal of the bias voltage generation circuit, used to generate a bias voltage.

[0022] Preferably, in one embodiment of the overcurrent protection circuit of this utility model, the current sampling unit includes a sampling resistor;

[0023] The first end of the sampling resistor is connected to the output terminal of the second switching unit, the input terminal of the second switching unit is connected to the power input terminal, and the second end of the sampling resistor is connected to the power output terminal.

[0024] Preferably, in one embodiment of the overcurrent protection circuit of this utility model, the second switching unit includes a controllable switch and a controllable switch driver;

[0025] The controllable switch is connected to the first switch unit and is used to generate a drive level according to the state of the first switch unit.

[0026] The controllable switch is connected to the controllable switch driver, the power input terminal, and the current sampling unit, and is used to turn on or off according to the driving level.

[0027] Preferably, in one embodiment of the overcurrent protection circuit of this utility model, the second switching unit further includes a latching circuit;

[0028] The level input terminal of the latch circuit is connected to the first switching unit and is used to generate a control level according to the state of the first switching unit;

[0029] The controllable switch is driven by the level output pin of the latch circuit, which is used to receive the control level generated by the latch circuit to maintain the off state.

[0030] This invention also constructs an electronic device, including the overcurrent protection circuit described above.

[0031] The overcurrent protection circuit and electronic device of this utility model have the following beneficial effects: they can reduce the power consumption of the current sampling circuit during the operation of the entire circuit. Attached Figure Description

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0033] Figure 1 This is a schematic diagram of an embodiment of an overcurrent protection circuit according to the present invention;

[0034] Figure 2 This is a circuit diagram of an embodiment of an overcurrent protection circuit according to this utility model;

[0035] Figure 3 This is a circuit diagram of another embodiment of the overcurrent protection circuit of this utility model;

[0036] Figure 4 This is a circuit diagram of another embodiment of the overcurrent protection circuit of this utility model. Detailed Implementation

[0037] To provide a clearer understanding of the technical features, objectives, and effects of this utility model, the specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0038] like Figure 1 The diagram illustrates an embodiment of an overcurrent protection circuit according to the present invention. Figure 1 An embodiment of the overcurrent protection circuit of the present invention shown includes: a power input terminal 110 for providing power input and a power output terminal 140 for providing power output, as well as a current sampling unit 130, a bias unit 160, a first switching unit 150, and a second switching unit 120; the current sampling unit 130 is connected between the power input terminal 110 and the power output terminal 140, and is used to generate a sampling result based on the output current of the power output terminal 140; the first switching unit 150 is connected to the current sampling unit 130, and is used to switch the state to conduct or turn off according to the sampling result of the current sampling unit 130; the bias unit 160 is connected to the first switching unit 150, and is used to provide a bias voltage to the first switching unit 150; the second switching unit 120 is connected between the power input terminal 110 and the power output terminal 140, and is connected to the first switching unit 150, and is used to switch the power input terminal 110 and the power output terminal 140 to conduct or turn off according to the state of the first switching unit 150.

[0039] Specifically, in this overcurrent protection circuit, the power input terminal 110 is used to connect to the power input, and the power output terminal 140 is used to provide the power output. In a specific embodiment, the power input terminal 110 can be used to connect to an external power supply or an upstream power supply to obtain the power input, and the power output terminal 140 can be used to connect to a load to provide the power output to the load. The load can be understood as the operating circuit of an electronic device. When the power input terminal 110 supplies power to the load through the power output terminal 140, the power input at the power input terminal 110 will form an output current at the power output terminal 140 as the operating current of the load. A current sampling unit 130 is disposed between the power input terminal 110 and the power output terminal 140 to sample the operating current of the load and generate a corresponding sampling result. A first switching unit 150 is used to receive the sampling result and switch its state according to the sampling result, for example, switching the first switching unit 150 to an on or off state. A second switching unit 120 turns the power input terminal 110 and the power output terminal 140 on or off according to the state of the first switching unit 150. For example, when the sampling result of the current sampling unit 130 determines that the operating current of the load 200 is too large, the first switching unit 150 turns on according to the sampling result, and the second switching unit 120 turns off, so as to cut off the output of the power output terminal 140 to the load, and finally realize the overcurrent protection of the load.

[0040] When the first switching unit 150 switches states based on the sampling results of the current sampling unit 130, the switching process is actually controlled by the sampling results of the current sampling unit 130 and the bias voltage provided by the bias unit 160. Normally, without a bias voltage, the first switching unit 150 only switches when the sampling results of the current sampling unit 130 reach a certain requirement, such as exceeding a certain threshold value. To meet this threshold requirement, the current sampling unit 130 requires significant power consumption. By setting the bias voltage, the threshold value requirement of the first switching unit 150 for the sampling results can be reduced, thus lowering the requirements of the first switching unit 150 on the current sampling unit 130. Simultaneously, setting a smaller threshold value reduces the power consumption of the current sampling unit 130 and keeps its operating state more stable, thereby improving the sampling accuracy of the current sampling unit 130.

[0041] like Figures 2 to 3As shown, in one embodiment, the first switching unit 150 includes a first resistor, a second resistor, and a transistor; the first end of the first resistor is connected to the first end of the current sampling unit 130, and the second end of the first resistor is connected to the emitter of the transistor; the base of the transistor is connected to the second end of the current sampling unit 130 via the second resistor, and the collector of the transistor is connected to the control terminal of the second switching unit 120; the emitter of the transistor is also connected to the bias unit 160 for receiving bias voltage. Specifically, the switching function can be implemented using a transistor circuit. The transistor circuit may include a transistor Q1. A current sampling unit 130 creates a voltage difference between the emitter and base of transistor Q1 (corresponding to the sampling result of the current sampling unit 130). This voltage difference, together with the bias voltage, serves as the VBE voltage of transistor Q1 between its emitter and base. When this VBE voltage reaches the turn-on voltage of transistor Q1, transistor Q1 turns on. Because the bias voltage is a fixed value, the actual operation of transistor Q1 is based on the voltage difference measured by the current sampling unit 130, causing it to turn on or off. A first resistor and a second resistor are used to limit current. These resistors can be single resistors or composed of multiple resistors. For example, the first resistor may include resistor R1, and the second resistor may include resistor R2. Resistor R1 limits the emitter current of transistor Q1, and resistor R2 limits the base current of transistor Q1. In another specific embodiment, by selecting the parameters of the above components, when the output current of the power supply output terminal 140 to the load 200 is 0 or a preset value, the transistor Q1 is in a slightly conducting state, thereby reducing the voltage difference required for the transistor Q1 to conduct. This allows for a smaller voltage difference across the current sampling unit 130, enabling the current sampling unit 130 to select a smaller resistance value and generate less power consumption under the same load current. This results in a smaller load and PCB area, reducing the cost of the overcurrent protection circuit. Simultaneously, as the power consumption of the current sampling unit 130 decreases, the heat generated by the current sampling unit 130 decreases, and the temperature rise of the current sampling unit 130 decreases, thus reducing the temperature drift error caused by the temperature rise, ultimately improving the accuracy of the entire overcurrent protection circuit.

[0042] In one embodiment, such as Figure 3 and Figure 4As shown, the bias unit 160 includes a third resistor and a bias voltage generation circuit 161. The first terminal of the bias voltage generation circuit 161 is connected to the first terminal of the third resistor for outputting a bias voltage. The second terminal of the third resistor is connected to the emitter of the transistor, and the second terminal of the bias voltage generation circuit 161 is connected to the power output terminal 140. Specifically, in the bias unit 160, a bias voltage can be generated by the bias voltage generation circuit 161 and current-limited by the third resistor. The third resistor can be a single resistor or composed of multiple resistors. For example, the third resistor includes resistor R3, and the bias voltage is input to the emitter of transistor Q1 through resistor R3. This increases the voltage difference between the emitter and base of transistor Q1, so that only a small voltage difference is needed from the current sampling unit 130 to enable transistor Q1 to switch states, such as turning on.

[0043] In one embodiment, such as Figure 4 As shown, the bias unit 160 also includes a fourth resistor and a voltage regulator circuit. The first terminal of the bias voltage generation circuit 161 is connected to the first terminal of the fourth resistor, the second terminal of the fourth resistor is connected to the first terminal of the third resistor and the first terminal of the voltage regulator circuit, and the second terminal of the voltage regulator circuit is connected to the second terminal of the bias voltage generation circuit 161. Specifically, the output of the bias voltage generation circuit 161 can be regulated by the voltage regulator circuit to obtain a stable bias voltage at the emitter of transistor Q1. Simultaneously, the output of the bias voltage generation circuit 161 can also be current-limited by the fourth resistor. The fourth resistor can be a single resistor or composed of multiple resistors. For example, the fourth resistor includes resistor R4.

[0044] In one embodiment, the voltage regulator circuit includes a Zener diode; the first terminal of the Zener diode is connected to the power output terminal 140, and the second terminal of the Zener diode is connected to the first terminal of a third resistor. Specifically, the voltage regulator circuit can be a Zener diode. In a specific embodiment, the Zener diode may include a Zener diode D1, the anode of the Zener diode D1 (corresponding to the first terminal of the Zener diode) is connected to the power output terminal 140, and the cathode of the Zener diode D1 is connected to the first terminal of the resistor R3 to regulate the bias voltage input to the first terminal of the resistor R3. The Zener diode D1 regulates the voltage based on the output voltage of the power output terminal 140.

[0045] In one embodiment, the bias voltage generation circuit 161 includes a DC-DC converter module. The input terminal of the DC-DC converter module is used to input a supply voltage, and the output terminal of the DC-DC converter module is the first terminal of the bias voltage generation circuit 161, used to generate a bias voltage. Specifically, in the bias voltage generation circuit 161, the DC-DC converter module can be configured to perform voltage conversion to obtain the required output voltage, and this output voltage is used as the bias voltage output of transistor Q1 through the first terminal of the bias voltage generation circuit 161. The DC-DC converter module can select a suitable voltage conversion chip as needed and construct the corresponding peripheral circuit of the chip to obtain the corresponding voltage output.

[0046] In one embodiment, the current sampling unit 130 includes a sampling resistor; the first end of the sampling resistor is connected to the output terminal of the second switching unit 120, the input terminal of the second switching unit 120 is connected to the power input terminal 110, and the second end of the sampling resistor is connected to the power output terminal 140. Specifically, the current sampling unit 130 can be composed of a sampling resistor RS. The operating current of the load 200 forms a voltage difference across the sampling resistor RS, which is superimposed between the emitter and base of the transistor Q1. Due to the presence of the bias voltage, the voltage difference across the sampling resistor RS required for the transistor Q1 to conduct can be reduced. This allows the sampling resistor to be selected with a smaller resistance value, resulting in less power consumption under the same load current 200, thereby achieving a smaller load 200 and PCB area, and reducing the cost of the overcurrent protection circuit. At the same time, as the power consumption of the sampling resistor decreases, the heat generated by the sampling resistor decreases, the temperature rise of the sampling resistor decreases, and the resistance temperature drift error caused by the temperature rise decreases, ultimately achieving high precision for the entire overcurrent protection circuit.

[0047] In one embodiment, the second switching unit 120 includes a controllable switch 121 and a controllable switch driver 122. The controllable switch driver 122 is connected to the first switching unit 150 and is used to generate a drive level according to the state of the first switching unit 150. The controllable switch 121 is connected to the controllable switch driver 122, the power input terminal 110, and the current sampling unit 130, and is used to turn on or off according to the drive level. Specifically, in the second switching unit 120, the controllable switch driver 122 outputs a drive level according to the state of the first switching unit 150. For example, it outputs a first level, such as a low level, when the first switching unit 150 is off, and outputs a second level, such as a high level, when the first switching unit 150 is on. The controllable switch 121 turns on or off according to the drive level. For example, the controllable switch 121 remains on when receiving a low level and turns off when receiving a high level, ultimately achieving overcurrent protection.

[0048] In one embodiment, the second switching unit 120 further includes a latch circuit 123. The level input terminal of the latch circuit 123 is connected to the first switching unit 150, and is used to generate a control level based on the state of the first switching unit 150. The controllable switch driver 122 is connected to the level output pin of the latch circuit 123, and is used to receive the control level generated by the latch circuit 123 to maintain the switch off. Specifically, the latch circuit 123 can generate an inhibit signal as the control level based on the operating state of the first switching unit 150, such as when it is on. This inhibit signal disables the controllable switch driver 122, thereby closing the controllable switch 121. Simultaneously, the inhibit signal maintains the off state of the controllable switch 121, ensuring that the controllable switch 121 remains off until the latch circuit 123 is reset. The latch circuit 123 can be composed of existing circuits or modules, such as a latch chip and its peripheral circuits, to generate and latch the corresponding control level triggered by the output level of the first switching unit 150.

[0049] In one specific embodiment, the controllable switch 121 includes a MOSFET switch, a SCR switch, or a relay switch; the controllable switch driver 122 may correspondingly include a MOSFET driver, a SCR driver, or a relay driver. For example... Figures 2 to 4 In one embodiment, the MOSFET switch may include a MOSFET M1 to control the output of the power input terminal 110 (corresponding to VDD) to the power output terminal.

[0050] Furthermore, this utility model discloses an electronic device including the overcurrent protection circuit described in the above embodiment. That is, during the operation of the electronic device, the internal working circuit can be connected to a power supply through this overcurrent protection circuit, and the power supply provides current to the working circuit. When the supply current is too high, the overcurrent protection circuit can shut off the power supply output to the working circuit, thus achieving overcurrent protection.

[0051] It is understood that the above embodiments only illustrate preferred embodiments of the present utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present utility model patent. It should be noted that for those skilled in the art, the above technical features can be freely combined, and several modifications and improvements can be made without departing from the concept of the present utility model, all of which fall within the protection scope of the present utility model. Therefore, all equivalent transformations and modifications made within the scope of the claims of the present utility model should fall within the coverage of the claims of the present utility model.

Claims

1. An overcurrent protection circuit, characterized in that, include: The power input terminal for providing power input and the power output terminal for providing power output, as well as a current sampling unit, a bias unit, a first switching unit and a second switching unit; The current sampling unit is connected between the power input terminal and the power output terminal, and is used to generate sampling results based on the output current of the power output terminal. The first switching unit is connected to the current sampling unit and is used to switch the state to turn on or off according to the sampling result of the current sampling unit. The bias unit is connected to the first switching unit and is used to provide a bias voltage to the first switching unit; The second switching unit is connected between the power input terminal and the power output terminal, and is also connected to the first switching unit, for switching the power input terminal and the power output terminal on or off according to the state of the first switching unit.

2. The overcurrent protection circuit according to claim 1, characterized in that, The first switching unit includes a first resistor, a second resistor, and a transistor; The first end of the first resistor is connected to the first end of the current sampling unit, and the second end of the first resistor is connected to the emitter of the transistor. The base of the transistor is connected to the second terminal of the current sampling unit via the second resistor, and the collector of the transistor is connected to the control terminal of the second switching unit. The emitter of the transistor is also connected to the bias unit for receiving the bias voltage.

3. The overcurrent protection circuit according to claim 2, characterized in that, The bias unit includes a third resistor and a bias voltage generation circuit; The first terminal of the bias voltage generation circuit is connected to the first terminal of the third resistor and is used to output the bias voltage. The second end of the third resistor is connected to the emitter of the transistor, and the second end of the bias voltage generation circuit is connected to the power supply output.

4. The overcurrent protection circuit according to claim 3, characterized in that, The biasing unit also includes a fourth resistor and a voltage regulator circuit; The first terminal of the bias voltage generating circuit is connected to the first terminal of the fourth resistor, the second terminal of the fourth resistor is connected to the first terminal of the third resistor and the first terminal of the voltage regulator circuit, and the second terminal of the voltage regulator circuit is connected to the second terminal of the bias voltage generating circuit.

5. The overcurrent protection circuit according to claim 4, characterized in that, The voltage regulator circuit includes a Zener diode; The first end of the Zener diode is connected to the power output terminal, and the second end of the Zener diode is connected to the first end of the third resistor.

6. The overcurrent protection circuit according to claim 3, characterized in that, The bias voltage generation circuit includes a DC-DC conversion module; The input terminal of the DC-DC conversion module is used to input a power supply voltage, and the output terminal of the DC-DC conversion module is the first terminal of the bias voltage generation circuit, used to generate a bias voltage.

7. The overcurrent protection circuit according to claim 1, characterized in that, The current sampling unit includes a sampling resistor; The first end of the sampling resistor is connected to the output terminal of the second switching unit, the input terminal of the second switching unit is connected to the power input terminal, and the second end of the sampling resistor is connected to the power output terminal.

8. The overcurrent protection circuit according to claim 1, characterized in that, The second switching unit includes a controllable switch and a controllable switch driver; The controllable switch is connected to the first switch unit and is used to generate a drive level according to the state of the first switch unit. The controllable switch is connected to the controllable switch driver, the power input terminal, and the current sampling unit, and is used to turn on or off according to the driving level.

9. The overcurrent protection circuit according to claim 8, characterized in that, The second switching unit also includes a latching circuit; The level input terminal of the latch circuit is connected to the first switching unit and is used to generate a control level according to the state of the first switching unit; The controllable switch is driven by the level output pin of the latch circuit, which is used to receive the control level generated by the latch circuit to maintain the off state.

10. An electronic device, characterized in that, Includes the overcurrent protection circuit as described in any one of claims 1 to 9.

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