CN211556844U - High-side switch circuit with current protection function - Google Patents
High-side switch circuit with current protection function Download PDFInfo
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- CN211556844U CN211556844U CN202020407692.2U CN202020407692U CN211556844U CN 211556844 U CN211556844 U CN 211556844U CN 202020407692 U CN202020407692 U CN 202020407692U CN 211556844 U CN211556844 U CN 211556844U
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Abstract
A high-side switch circuit with a current protection function comprises a voltage input end, a voltage output end, a control signal input end, a first switch element, a current sampling circuit, a starting circuit, an overcurrent protection circuit, a protection state latch circuit and a first switch element control circuit. The first switching element is connected to the voltage input terminal and the voltage output terminal, respectively, and the current sampling circuit samples a current flowing through the first switching element. The input end of the starting circuit is connected with the output end of the current sampling circuit, and the output end of the starting circuit is connected with the control end of the overcurrent protection circuit. The protection state latch circuit is respectively connected with the voltage input end and the overcurrent protection circuit; the control input end of the first switch element control circuit is respectively connected with the control signal input end of the high-side switch circuit and the output end of the overcurrent protection circuit, and the output end of the first switch element control circuit is connected with the control input end of the first switch element Q1. The utility model discloses it is with low costs, can latch the guard state to have the overcurrent protection function.
Description
Technical Field
The utility model relates to a protection circuit technique especially relates to high limit switch circuit.
Background
The following two common overcurrent protection methods are mainly used: the first way is to use a fuse that blows when an overcurrent occurs. By adopting the mode, the circuit can not be recovered by self, and the fuse needs to be replaced; the second mode is to use an intelligent high-side switch, and by adopting the protection mode, the protection state can be recovered by self.
The intelligent high-side switch with the current protection function in the current market mostly adopts an integrated scheme and is high in cost.
Disclosure of Invention
The utility model aims to solve the technical problem that a high limit switch circuit with low costs, can latch the protection state, have the overcurrent protection function is provided.
Another technical problem to be solved by the present invention is to provide a high-side switching circuit capable of resetting a latched protection state.
The embodiment of the utility model provides a high side switch circuit with current protection function, including voltage input end, voltage output end, control signal input end, first switch element Q1 and current sampling circuit; a first terminal and a second terminal of the first switching element Q1 are connected to the voltage input terminal and the voltage output terminal, respectively, and the current sampling circuit is configured to sample a current flowing through the first switching element Q1 and output a voltage signal corresponding to the current; the high-side switch circuit also comprises a starting circuit, an overcurrent protection circuit, a protection state latch circuit and a first switch element control circuit; the input end of the starting circuit is connected with the output end of the current sampling circuit, and the output end of the starting circuit is connected with the control end of the overcurrent protection circuit, so that the overcurrent protection circuit is started when the current flowing through the first switching element Q1 exceeds a preset overcurrent threshold; the overcurrent protection circuit is used for outputting a working signal to the protection state latch circuit when the overcurrent protection circuit is started and outputting a turn-off signal to the first switching element control circuit; the protection state latch circuit is respectively connected with the voltage input end of the high-side switch circuit and the overcurrent protection circuit and is used for latching a turn-off signal output by the overcurrent protection circuit when receiving a working signal; the control input end of the first switch element control circuit is respectively connected with the control signal input end of the high-side switch circuit and the output end of the overcurrent protection circuit, the output end of the first switch element control circuit is connected with the control input end of the first switch element Q1, the first switch element control circuit controls the action of the first switch element Q1 according to the control signal input from the control signal input end of the high-side switch circuit when not receiving the turn-off signal, and turns off the first switch element Q1 and enables the first switch element Q1 to maintain the turn-off state when receiving the turn-off signal.
Further, the utility model discloses high limit switch circuit includes reset circuit, and reset circuit's reset signal input end is used for receiving external input's reset signal, and reset circuit's power input end is connected with high limit switch circuit's voltage input end, reset circuit's output respectively with overcurrent protection circuit's control end and protection state latch circuit connect, reset circuit is used for removing the latch of protection state latch circuit to the turn-off signal of overcurrent protection circuit output.
The utility model discloses at least, following technological effect has:
1. the high-side switch circuit provided by the embodiment of the utility model is composed of discrete devices, the cost is low, the overcurrent threshold value of the high-side switch circuit can be flexibly set by changing the resistance value of the sampling resistor, once the current flowing through the first switch element Q1 exceeds the overcurrent threshold value, the overcurrent protection circuit can rapidly turn off the first switch element Q1, and meanwhile, the protection state latch circuit can latch the protection state, so that the current-limiting protection is realized, and the protection state can be latched, so that the overcurrent protection function of the embodiment is more stable and reliable compared with the prior art;
2. the utility model discloses high limit switch circuit still is equipped with reset circuit, can reset by the guard state who latches.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 shows a schematic circuit diagram of a high-side switching circuit according to a first embodiment of the present invention.
Fig. 2 shows an operating state transition diagram of a high-side switching circuit according to a first embodiment of the present invention.
Fig. 3 shows a circuit schematic of a high-side switching circuit according to a second embodiment of the present invention.
Fig. 4 shows a circuit schematic of a high-side switching circuit according to a third embodiment of the present invention.
Detailed Description
The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
Fig. 1 shows a schematic circuit diagram of a high-side switching circuit according to a first embodiment of the present invention. Please refer to fig. 1. According to the utility model discloses a high limit switch circuit with current protect function of first embodiment, including voltage input end In, voltage Output end Output, control signal input end s, first switching element Q1, current sampling circuit 1, starting circuit 2, overcurrent protection circuit 3, protection state latch circuit 4, first switching element control circuit 5 and reset circuit 6.
The first terminal and the second terminal of the first switching element Q1 are connected to a voltage input terminal In and a voltage Output terminal Output, respectively, and the current sampling circuit 1 is configured to sample a current flowing through the first switching element Q1 and Output a voltage signal corresponding to the current flowing through the first switching element Q1.
The input end of the starting circuit 2 is connected with the output end of the current sampling circuit 1, the output end of the starting circuit 2 is connected with the first control end of the overcurrent protection circuit 3, and the starting circuit 2 starts the overcurrent protection circuit 3 when the current flowing through the first switching element Q1 exceeds a preset overcurrent threshold.
The overcurrent protection circuit 3 is configured to output a working signal to the protection state latch circuit 4 at the time of start-up, and output a shutdown signal to the first switching element control circuit 5.
The protection state latch circuit 4 is respectively connected with the voltage input end In of the high-side switch circuit and the overcurrent protection circuit 3, and is used for latching a turn-off signal output by the overcurrent protection circuit 3 when receiving a working signal.
The control input terminal of the first switching element control circuit 5 is connected to the control signal input terminal s of the high-side switching circuit and the output terminal of the overcurrent protection circuit 3, respectively, the output terminal of the first switching element control circuit 5 is connected to the control input terminal of the first switching element Q1, the first switching element control circuit 5 controls the operation of the first switching element Q1 according to the control signal input from the control signal input terminal s of the high-side switching circuit when the turn-off signal is not received, and turns off the first switching element Q1 and maintains the turn-off state of the first switching element Q1 when the turn-off signal is received.
The reset signal input end r of the reset circuit 6 is used for receiving an externally input reset signal, the power input end of the reset circuit 6 is connected with the voltage input end In of the high-side switch circuit, the output end of the reset circuit 6 is respectively connected with the control end of the overcurrent protection circuit 3 and the protection state latch circuit 4, and the reset circuit 6 is used for releasing the latch of the shutdown signal output by the overcurrent protection circuit 3 by the protection state latch circuit 4, namely resetting the latched protection state.
The first switching element control circuit 5 includes a second switching element Q2, a control terminal of the second switching element Q2 is connected to the control signal input terminal s of the high-side switching circuit and the output terminal of the overcurrent protection circuit 3, respectively, a first terminal of the second switching element Q2 is connected to the control input terminal of the first switching element Q1, and a second terminal of the second switching element Q2 is grounded.
The overcurrent protection circuit 3 includes a fifth switching element Q5 and a diode D2; the protection state latch circuit 4 includes a fourth switching element Q4. A first terminal of the fourth switching element Q4 is connected to the voltage input terminal In of the high-side switching circuit. A control terminal of the fifth switching element Q5 is connected to the output terminal of the start circuit 2 and the second terminal of the fourth switching element Q4, respectively, a first terminal of the fifth switching element Q5 is connected to the control terminal of the fourth switching element Q4 and the cathode of the diode D2, respectively, a second terminal of the fifth switching element Q5 is grounded, and an anode of the diode D2 is connected to the control terminal of the second switching element Q2. When the fifth switching element Q5 is turned on, the fourth switching element Q4 is turned on, the diode D2 is forward biased, the second switching element Q2 is turned off when the diode D2 is forward biased, the first switching element Q1 is further turned off, and when the fourth switching element Q4 is turned on, the control terminal of the fifth switching element Q5 is connected to the voltage input terminal In of the high-side switching circuit, so that the output signal of the fifth switching element Q5 is kept unchanged, and the second switching element Q2 and the first switching element Q1 are further kept In an off state.
The reset circuit 6 includes a sixth switching element Q6 and a seventh switching element Q7. A control terminal of the seventh switching element Q7 is configured to receive an externally input reset signal, a first terminal of the seventh switching element Q7 is connected to the control terminal of the sixth switching element Q6 and the voltage input terminal In of the high-side switching circuit, and a second terminal of the seventh switching element Q7 is grounded. A first terminal of the sixth switching element Q6 is connected to the second terminal of the fourth switching element Q4 and the control terminal of the fifth switching element Q5, respectively, and a second terminal of the sixth switching element Q6 is grounded. The seventh switching element Q7 turns off when receiving an externally input reset signal, turns on the sixth switching element Q6, turns off the fifth switching element Q5 when the sixth switching element Q6 is on, turns off the fourth switching element Q4 when the fifth switching element Q5 is off, and reversely biases the diode D2.
In the present embodiment, the current sampling circuit 1 includes a sampling resistor R1, and the sampling resistor R1 is connected In series between the voltage input terminal In and the first terminal of the first switching element Q1. In other embodiments, the sampling resistor R1 is connected in series between the second terminal of the first switching element Q1 and the voltage Output terminal Output. The start circuit 2 includes a third switching element Q3, a first terminal and a control terminal of the third switching element Q3 are connected to both terminals of a sampling resistor R1, respectively, and a second terminal of the third switching element Q3 is connected to a control terminal of a fifth switching element Q5.
In this embodiment, the first switching element Q1 is a PMOS transistor, and the gate, the source and the drain of the PMOS transistor Q1 respectively form the control terminal, the first terminal and the second terminal of the first switching element Q1. The second switching element Q2 is an NMOS transistor, and the gate, the drain and the source of the NMOS transistor Q2 form a control terminal, a first terminal and a second terminal of the second switching element Q2, respectively. The third switching element Q3 is a PNP transistor, and the base, emitter, and collector of the PNP transistor Q3 form the control terminal, the first terminal, and the second terminal of the third switching element Q3, respectively. The fourth switching element Q4 is a PNP triode, and the base, emitter, and collector of the PNP triode Q4 form the control terminal, the first terminal, and the second terminal of the fourth switching element Q4, respectively. The fifth switching element Q5 is an NPN transistor, and a base, a collector, and an emitter of the NPN transistor Q5 constitute a control terminal, a first terminal, and a second terminal of the fifth switching element Q5, respectively. The sixth switching element Q6 is an NPN transistor, and a base, a collector, and an emitter of the NPN transistor Q6 respectively form a control terminal, a first terminal, and a second terminal of the sixth switching element Q6. The seventh switching element Q7 is an NPN transistor, and a base, a collector, and an emitter of the NPN transistor Q7 respectively constitute a control terminal, a first terminal, and a second terminal of the seventh switching element Q7.
Further, the first switching element control circuit 4 includes a voltage-dividing resistor R8, a voltage-dividing resistor R9, a control resistor R11, and a pull-down discharge resistor R12. One end of the voltage-dividing resistor R8 is connected to the first end of the first switching element Q1, the other end of the voltage-dividing resistor R8 is connected to the control end of the first switching element Q1 and one end of the voltage-dividing resistor R9, and the other end of the voltage-dividing resistor R9 is connected to the first end of the second switching element Q2. One end of the pull-down discharge resistor R12 is connected to the control terminal of the second switching element Q2, and the other end of the pull-down discharge resistor R12 is connected to the second terminal of the second switching control element Q2 and ground, respectively. One end of the control resistor R11 is connected to the output end of the overcurrent protection circuit 3 and the control end of the second switching element Q2, respectively, and the other end of the control resistor R11 is connected to the control signal input end s of the high-side switching circuit. Optionally, the voltage-dividing resistor R8 is connected in parallel with the voltage-stabilizing tube D1, the negative electrode of the voltage-stabilizing tube 8 is connected with one end of the voltage-dividing resistor R8, and the positive electrode of the voltage-stabilizing tube 8 is connected with the other end of the voltage-dividing resistor R8.
Further, the protection state latch circuit 4 includes a current limiting resistor R2 and a pull-up resistor R3, and the overcurrent protection circuit 3 includes a pull-up resistor R4. One end of a current limiting resistor R2 and one end of a pull-up resistor R3 are respectively connected with a voltage input end In of the high-side switching circuit, the other end of the current limiting resistor R2 is connected with an emitting electrode of a PNP triode Q4, the other end of the pull-up resistor R3 is connected with a base electrode of a PNP triode Q4, and a collector electrode of the PNP triode Q4 is connected with a base electrode of an NPN triode Q5. One end of the pull-up resistor R4 is connected to the output terminal of the start circuit 2 (i.e., the collector of the PNP transistor Q3), and the other end of the pull-up resistor R4 is connected to the common junction of the collector of the PNP transistor Q4 and the base of the NPN transistor Q5. The collector of the NPN transistor Q5 is connected to the base of the PNP transistor Q4 and the cathode of the diode D2, respectively, and the anode of the diode D2 is connected to the control terminal of the second switching element Q2. The anode of the diode D2 constitutes the output of the overcurrent protection circuit.
Further, the reset circuit 5 includes a pull-up resistor R5, a current limiting resistor R6, and a pull-down discharge resistor R7. One end of a pull-up resistor R5 is connected with a voltage input end In of the high-side switch circuit, and the other end of the pull-up resistor R5 is respectively connected with a base electrode of an NPN triode Q6 and a collector electrode of an NPN triode Q7. One end of the current limiting resistor R6 is used as a reset signal input end R of the reset circuit 5 and is used for receiving an externally input reset signal, the other end of the current limiting resistor R6 is respectively connected with the base of the NPN triode Q7 and one end of the pull-down discharge resistor R7, and the other end of the pull-down discharge resistor R7 is grounded.
In other embodiments, the first switching element Q1 is not limited to a PMOS transistor, and a relay or other switch may be used; the second switching element Q2 is not limited to NMOS, and a relay or other switch may be used; the fifth switching element Q5, the sixth switching element Q6, and the seventh switching element Q7 are not limited to NPN transistors, and NMOS transistors or relays may be used.
The Enable signal input to the control signal input terminal s of the high-side switch circuit corresponds to an Enable signal for enabling the high-side switch circuit to operate when the Enable signal is at a high level, and the Reset signal input to the control terminal r of the Reset circuit corresponds to a Reset signal when the Reset signal is at a low level. Fig. 2 shows an operating state transition diagram of a high-side switching circuit according to a first embodiment of the present invention. Combine fig. 2 to show, according to the utility model discloses high limit switch circuit has four kinds of operating modes:
working condition 1:
the Enable signal is high and no over-current occurs. At this time, the voltage drop across the sampling resistor R1 is smaller than the emitter base bias voltage of the PNP triode Q3, and the PNP triode Q3 is reversely biased and cut off; the base electrode of the NPN triode Q5 floats, and the NPN triode Q5 is cut off; the base electrode of the PNP triode Q4 is pulled up to Vin by a pull-up resistor R3 and is cut off, and Vin is the input voltage of the voltage input end In; the cathode of the diode D2 is pulled up to Vin by a pull-up resistor R3, the diode D2 is reversely biased to be cut off, the grid of the NMOS tube Q2 is controlled to be high by an Enable signal, the NMOS tube Q2 is conducted, the PMOS tube Q1 is further controlled to be conducted, and the Enable signal indirectly controls the conduction and the cut-off of the PMOS tube Q1 by controlling the conduction and the cut-off of the NMOS tube Q2. At this time, if the Reset signal is at a high level, the NPN transistor Q7 is turned on, the base of the NPN transistor Q6 is pulled to ground, and the NPN transistor Q6 is turned off; if the Reset signal is low, NPN transistor Q7 turns off, the base of NPN transistor Q6 is pulled up to Vin by pull-up resistor R5, and NPN transistor Q6 turns on.
In the operating condition 1, a current input from the voltage input terminal In of the high-side switching circuit flows to the voltage Output terminal Output through the first switching element Q1, and is Output to the load R10.
Working condition 2:
the Enable signal is low. At this time, the gate input signal of the NMOS transistor Q2 is low, the NMOS transistor Q2 is turned off, and the PMOS transistor Q1 is also turned off.
Working condition 3:
when the Enable signal is high, an overcurrent occurs.
When the Reset signal is high, NPN transistor Q7 turns on, and NPN transistor Q6 turns off. The base of NPN transistor Q5 is not pulled down to ground by NPN transistor Q6, and the base level of NPN transistor Q5 is controlled by PNP transistor Q3 and PNP transistor Q4.
Due to overcurrent (namely, the current flowing through the first switching element Q1 exceeds a predetermined overcurrent threshold, and the predetermined overcurrent threshold is related to the resistance of the sampling resistor R1), the voltage across the sampling resistor R1 exceeds the conduction voltage drop of the PNP transistor Q3, the PNP transistor Q3 is turned on, the voltage at the base of the NPN transistor Q5 is pulled up by the pull-up resistor R4, the NPN transistor Q5 is turned on (namely, the overcurrent protection circuit is started), so that the diode D2 is forward biased, the diode D2 is forward biased, the gate of the NMOS transistor Q2 is pulled to the ground, the NMOS transistor Q2 is turned off, and the PMOS transistor Q1 is turned off.
After the base electrode of the PNP triode Q4 is pulled to the ground by the NPN triode Q5, the PNP triode Q4 is conducted, the base electrode of the NPN triode Q5 is pulled to Vin by the current-limiting resistor R2 through the PNP triode Q4, the conducting state of the NPN triode Q5 is latched, and therefore the latching of the overcurrent protection state of the PMOS tube Q1 is achieved.
Working condition 4:
and when overcurrent protection occurs, the Reset signal is set to be low, and the Reset signal after the Reset signal is set to be low forms a Reset signal to Reset the overcurrent protection state.
When the Reset signal is set to be low, the NPN triode Q7 is turned off, the NPN triode Q6 is turned on, the base level of the NPN triode Q5 is pulled low, and the NPN triode Q6 is turned off; the base potential of the NPN triode Q4 rises, the NPN triode is turned off, and the diode D2 is reversely biased.
After the overcurrent protection state is reset, if the Enable signal is at a high level, the NMOS transistor Q2 is turned on, and the PMOS transistor Q1 is also turned on.
Fig. 3 shows a circuit schematic of a high-side switching circuit according to a second embodiment of the present invention. The second embodiment is mainly different from the first embodiment in that in the first embodiment, the control signal input terminal s of the high-side switch circuit and the Reset signal input terminal r of the Reset circuit are independent from each other, and the Enable signal and the Reset signal are separately input, whereas in the second embodiment, the Reset signal input terminal of the Reset circuit and the control signal input terminal of the high-side switch circuit are the same signal input terminal, the low-level signal input from the signal input terminal is the Reset signal Reset for releasing the latch of the protection state, the high-level signal input from the signal input terminal is the Enable signal Enable for enabling the high-side switch circuit to operate.
Fig. 4 shows a circuit schematic of a high-side switching circuit according to a third embodiment of the present invention. The main difference between this third embodiment and the first embodiment is that the reset circuit 6 in the first embodiment is removed from the third embodiment.
The utility model discloses high limit switch circuit comprises discrete device, therefore, the carrier wave prepaid electric energy meter is low in cost, the resistance through changing sampling resistance can set up this high limit switch circuit's the threshold value that overflows in a flexible way, in case the electric current that flows through first switch element surpasses this threshold value that overflows, overcurrent protection circuit can turn off first switch element Q1 rapidly, protection state latch circuit can latch protection state simultaneously, current-limiting protection has been realized, owing to can latch protection state, therefore the overcurrent protection function of this embodiment compares more reliable and more stable with prior art. In addition, the latch of the protection state can be released through the reset circuit, and the use is very flexible.
It will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (13)
1. A high-side switch circuit with a current protection function comprises a voltage input end, a voltage output end, a control signal input end, a first switch element Q1 and a current sampling circuit; a first end and a second end of a first switching element Q1 are respectively connected with the voltage input end and the voltage output end, the current sampling circuit is used for sampling the current flowing through the first switching element Q1 and outputting a voltage signal corresponding to the current, and the high-side switching circuit is characterized by further comprising a starting circuit, an overcurrent protection circuit, a protection state latch circuit and a first switching element control circuit;
the input end of the starting circuit is connected with the output end of the current sampling circuit, and the output end of the starting circuit is connected with the control end of the overcurrent protection circuit, so that the overcurrent protection circuit is started when the current flowing through the first switching element Q1 exceeds a preset overcurrent threshold;
the overcurrent protection circuit is used for outputting a working signal to the protection state latch circuit when the overcurrent protection circuit is started, and outputting a turn-off signal to the first switching element control circuit;
the protection state latch circuit is respectively connected with the voltage input end of the high-side switch circuit and the overcurrent protection circuit and is used for latching a turn-off signal output by the overcurrent protection circuit when receiving the working signal;
the control input end of the first switch element control circuit is respectively connected with the control signal input end of the high-side switch circuit and the output end of the overcurrent protection circuit, the output end of the first switch element control circuit is connected with the control input end of a first switch element Q1, the first switch element control circuit controls the action of a first switch element Q1 according to the control signal input from the control signal input end of the high-side switch circuit when not receiving the turn-off signal, and turns off the first switch element Q1 and enables the first switch element Q1 to maintain the turn-off state when receiving the turn-off signal.
2. The high-side switching circuit with current protection function according to claim 1, wherein the first switching element control circuit comprises a second switching element Q2, control terminals of the second switching element Q2 are respectively connected with the control signal input terminal of the high-side switching circuit and the output terminal of the over-current protection circuit, a first terminal of a second switching element Q2 is connected with the control input terminal of the first switching element Q1, and a second terminal of the second switching element Q2 is grounded.
3. The high-side switch circuit with current protection function as claimed in claim 2, wherein said first switch element Q1 is a PMOS transistor, and the gate, source and drain of said PMOS transistor respectively constitute the control terminal, first terminal and second terminal of the first switch element Q1.
4. The high-side switch circuit with current protection function as claimed in claim 2 or 3, wherein the second switch element Q2 is an NMOS transistor, and the gate, drain and source of the NMOS transistor respectively constitute the control terminal, the first terminal and the second terminal of the second switch element Q2;
the first switching element control circuit includes a voltage dividing resistor R8, a voltage dividing resistor R9, and a pull-down discharge resistor R12; one end of a voltage-dividing resistor R8 is connected to a first end of the first switching element Q1, the other end of the voltage-dividing resistor R8 is connected to a control end of the first switching element Q1 and one end of a voltage-dividing resistor R9, respectively, and the other end of the voltage-dividing resistor R9 is connected to a first end of the second switching element Q2; one end of the pull-down discharge resistor R12 is connected to the control terminal of the second switching element, and the other end of the pull-down discharge resistor R12 is connected to the second terminal of the second switching control element Q2 and ground, respectively.
5. The high-side switch circuit with current protection function according to claim 4, wherein the first switch element control circuit comprises a control resistor R11, one end of the control resistor R11 is connected to the output terminal of the over-current protection circuit and the control terminal of the second switch element Q2, respectively, and the other end of the control resistor R11 is connected to the control signal input terminal of the high-side switch circuit.
6. The high-side switching circuit with current protection function according to claim 2, wherein the overcurrent protection circuit comprises a fifth switching element Q5 and a diode D2; the protection state latch circuit comprises a fourth switching element Q4;
a control end of the fifth switching element Q5 is respectively connected with the output end of the starting circuit and a second end of the fourth switching element Q4, a first end of the fifth switching element Q5 is respectively connected with a control end of the fourth switching element Q4 and a cathode of the diode D2, a second end of the fifth switching element Q5 is grounded, and an anode of the diode D2 is connected with a control end of the second switching element Q2;
a first end of a fourth switching element Q4 is connected with a voltage input end of the high-side switching circuit;
when the fifth switching element Q5 is turned on, the fourth switching element Q4 is turned on, the diode D2 is forward biased, the second switching element Q2 is turned off when the diode D2 is forward biased, the first switching element Q1 is further turned off, and when the fourth switching element Q4 is turned on, the control terminal of the fifth switching element Q5 is connected to the voltage input terminal of the high-side switching circuit, so that the output signal of the fifth switching element Q5 is kept unchanged.
7. The high-side switch circuit with current protection function according to claim 6, wherein the current sampling circuit comprises a sampling resistor R1, the sampling resistor R1 is connected in series between the voltage input terminal and the first terminal of the first switch element Q1 or between the second terminal of the first switch element Q1 and the voltage output terminal;
the start-up circuit includes a third switching element Q3, a first terminal and a control terminal of the third switching element Q3 are connected to both terminals of a sampling resistor R1, respectively, and a second terminal of the third switching element Q3 is connected to a control terminal of a fifth switching element Q5.
8. The high-side switch circuit with current protection function according to claim 7, wherein the third switching element Q3 is a PNP transistor Q3; the base, emitter, and collector of the PNP transistor Q3 constitute a control terminal, a first terminal, and a second terminal of the third switching element Q3, respectively.
9. The high-side switching circuit with current protection function according to claim 6, 7 or 8, wherein the fourth switching element Q4 is a PNP transistor Q4, and the base, emitter and collector of the PNP transistor Q4 respectively form the control terminal, the first terminal and the second terminal of the fourth switching element Q4; the fifth switching element Q5 is an NPN transistor Q5, and a base, a collector, and an emitter of the NPN transistor Q5 respectively constitute a control terminal, a first terminal, and a second terminal of the fifth switching element Q5;
the protection state latch circuit comprises a current limiting resistor R2 and a pull-up resistor R3, and the overcurrent protection circuit comprises a pull-up resistor R4; one end of a current limiting resistor R2 and one end of a pull-up resistor R3 are respectively connected with the voltage input end of the high-side switch circuit, the other end of the current limiting resistor R2 is connected with the emitting electrode of a PNP triode Q4, the other end of the pull-up resistor R3 is connected with the base electrode of a PNP triode Q4, and the collector electrode of the PNP triode Q4 is connected with the base electrode of an NPN triode Q5; one end of a pull-up resistor R4 is connected with the output end of the starting circuit, and the other end of the pull-up resistor R4 is connected with the common junction of the collector of the PNP triode Q4 and the base of the NPN triode Q5;
the collector of the NPN transistor Q5 is connected to the base of the PNP transistor Q4 and the cathode of the diode D2, respectively, and the anode of the diode D2 is connected to the control terminal of the second switching element Q2.
10. The high-side switch circuit with the current protection function according to claim 1, 2 or 3, wherein the high-side switch circuit comprises a reset circuit, a reset signal input end of the reset circuit is configured to receive an externally input reset signal, a power input end of the reset circuit is connected to a voltage input end of the high-side switch circuit, an output end of the reset circuit is respectively connected to the control end of the over-current protection circuit and the protection state latch circuit, and the reset circuit is configured to release latching of the protection state latch circuit on the off signal output by the over-current protection circuit.
11. The high-side switching circuit with current protection function according to claim 6, wherein the high-side switching circuit comprises a reset circuit, the reset circuit comprises a sixth switching element Q6 and a seventh switching element Q7;
a control terminal of the seventh switching element Q7 is configured to receive an externally input reset signal, a first terminal of the seventh switching element Q7 is connected to the control terminal of the sixth switching element Q6 and the voltage input terminal of the high-side switching circuit, and a second terminal of the seventh switching element Q7 is grounded; a first terminal of the sixth switching element Q6 is connected to the second terminal of the fourth switching element Q4 and the control terminal of the fifth switching element Q5, respectively, and a second terminal of the sixth switching element Q6 is grounded;
the seventh switching element Q7 turns off when receiving an externally input reset signal, turns on the sixth switching element Q6, turns off the fifth switching element Q5 when the sixth switching element Q6 is on, turns off the fourth switching element Q4 when the fifth switching element Q5 is off, and reversely biases the diode D2.
12. The high-side switching circuit with current protection function as claimed in claim 11, wherein the sixth switching element Q6 is an NPN transistor Q6, and the base, collector and emitter of the NPN transistor Q6 respectively constitute the control terminal, the first terminal and the second terminal of the sixth switching element Q6; the seventh switching element Q7 is an NPN transistor Q7, and a base, a collector, and an emitter of the NPN transistor Q7 respectively form a control end, a first end, and a second end of the seventh switching element Q7;
the reset circuit comprises a pull-up resistor R5, a current-limiting resistor R6 and a pull-down discharge resistor R7; one end of a pull-up resistor R5 is connected with the voltage input end of the high-side switch circuit, and the other end of the pull-up resistor R5 is respectively connected with the base electrode of an NPN triode Q6 and the collector electrode of an NPN triode Q7; one end of the current-limiting resistor R6 is used for receiving an externally input reset signal, the other end of the current-limiting resistor R6 is respectively connected with the base of the NPN triode Q7 and one end of the pull-down discharge resistor R7, and the other end of the pull-down discharge resistor R7 is grounded.
13. The high-side switching circuit with current protection as claimed in claim 10, wherein the reset signal input of the reset circuit and the control signal input of the high-side switching circuit are the same signal input.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111313361A (en) * | 2020-03-26 | 2020-06-19 | 科博达技术股份有限公司 | High-side switch circuit with current protection function |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111313361A (en) * | 2020-03-26 | 2020-06-19 | 科博达技术股份有限公司 | High-side switch circuit with current protection function |
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