Overcurrent protection circuit and control chip

Abstract

The utility model discloses an overcurrent protection circuit and a control chip, the overcurrent protection circuit comprises a diverter, a first switch circuit and a second switch circuit, the first end of the diverter is electrically connected with a power supply input end, and the second end of the diverter is electrically connected with a switch device; the first end of the first switching circuit is electrically connected with the power input end, and the second end of the first switching circuit is electrically connected with the second end of the shunt; the first end of the second switching circuit is electrically connected with the third end of the first switching circuit, and the second end of the second switching circuit is grounded; the first switching circuit is used for working when the voltage drop on the shunt reaches a preset voltage value to output a first turn-off signal to a controlled end of the switching device so as to control the switching device to disconnect a path between a load and a power supply input end; and the second switch circuit is used for outputting a second turn-off signal to enable the first switch circuit to be in the turn-off state when in the turn-off state. The utility model aims to provide the overcurrent protection circuit and the control chip so as to realize overcurrent protection.

Description

Technical Field

[0001] The present application relates to the field of IO control technology, and in particular to an overcurrent protection circuit and a control chip. Background Art

[0002] At present, in the field of IO control, source modules mainly use integrated dedicated chips to implement the hiccup overcurrent protection function of IO channels. However, the current mainstream dedicated chips are expensive and the supply is unstable, so it is imperative to find new alternatives. Therefore, how to design a low-cost control with no special requirements for material selection is a technical problem that needs to be solved in this field. Utility Model Content

[0003] The main purpose of the utility model is to provide an overcurrent protection circuit and a control chip, aiming to provide an overcurrent protection circuit and a control chip to achieve overcurrent protection.

[0004] To achieve the above object, the utility model proposes an overcurrent protection circuit, which is applied to an IO control circuit. The IO control circuit includes a power input terminal, a load, and a switch device electrically connected in series between the power input terminal and the load. The overcurrent protection circuit includes:

[0005] A shunt, wherein a first end of the shunt is electrically connected to a power input end, and a second end of the shunt is electrically connected to the switch device;

[0006] a first switch circuit, wherein a first end of the first switch circuit is electrically connected to a power input end, and a second end of the first switch circuit is electrically connected to a second end of the shunt;

[0007] a second switch circuit, wherein a first end of the second switch circuit is electrically connected to a third end of the first switch circuit, and a second end of the second switch circuit is grounded;

[0008] The first switch circuit is used to operate when the voltage drop on the shunt reaches a preset voltage value to output a first shutdown signal to the controlled end of the switch device to control the switch device to disconnect the path between the load and the power input end;

[0009] The second switch circuit is used to output a second shutdown signal to put the first switch circuit in an off state when the second switch circuit is in an off state.

[0010] Optionally, the first switch circuit includes:

[0011] a first switch branch, wherein a first end of the first switch branch is electrically connected to a power input end, and a third end of the first switch branch is electrically connected to the switch device;

[0012] A second switch branch, wherein a first end of the second switch branch is electrically connected to a second end of the first switch branch, and a second end of the second switch branch is electrically connected to the second switch circuit.

[0013] Optionally, the first switch branch includes:

[0014] A first switching tube;

[0015] a first resistor, wherein a first end of the first resistor is electrically connected to a first end of the first switch tube and a first end of the shunt, respectively, and a second end of the first resistor is electrically connected to a second end of the first switch tube;

[0016] a second resistor, wherein a first end of the second resistor is electrically connected to a second end of the first resistor, and a second end of the second resistor is electrically connected to a second end of the shunt;

[0017] A first capacitor, wherein a first end of the first capacitor is electrically connected to a first end of the first resistor, and a second end of the first capacitor is electrically connected to a second end of the first resistor.

[0018] Optionally, the first switch branch further includes:

[0019] A unidirectional conducting circuit, wherein a first end of the unidirectional conducting circuit is electrically connected to the third end of the first switch tube, and a second end of the unidirectional conducting circuit is electrically connected to the controlled end of the switch device.

[0020] Optionally, the second switch branch includes:

[0021] a second switch tube, wherein a first end of the second switch tube is electrically connected to a second end of the first switch tube, and a second end of the second switch tube is electrically connected to a third end of the first switch tube;

[0022] a third resistor, wherein a first end of the third resistor is electrically connected to the second end of the second switch tube, and a second end of the third resistor is electrically connected to the third end of the second switch tube;

[0023] A fourth resistor, wherein a first end of the fourth resistor is electrically connected to a second end of the third resistor, and a second end of the fourth resistor is electrically connected to the second switch circuit.

[0024] Optionally, the second switch circuit includes:

[0025] a first voltage divider circuit, wherein a first end of the first voltage divider circuit is electrically connected to the power input end, and a second end of the first voltage divider circuit is grounded;

[0026] A third switch branch, wherein a first end of the third switch branch is electrically connected to a second end of the second switch branch, a second end of the third switch branch is electrically connected to the first voltage divider circuit, and a third end of the third switch branch is grounded.

[0027] Optionally, the first voltage divider circuit includes:

[0028] a first voltage-dividing resistor, wherein a first end of the first voltage-dividing resistor is electrically connected to the power input end, and a second end of the first voltage-dividing resistor is electrically connected to the second end of the third switch branch;

[0029] A second voltage-dividing resistor, wherein a first end of the second voltage-dividing resistor is electrically connected to a second end of the first voltage-dividing resistor, and a second end of the second voltage-dividing resistor is electrically connected to a third end of the third switch branch.

[0030] Optionally, the third switch branch includes:

[0031] A third switch tube, wherein a first end of the third switch tube is electrically connected to a second end of the second switch branch, a second end of the third switch tube is electrically connected to a second end of the first voltage-dividing resistor, and a third end of the third switch tube is grounded.

[0032] Optionally, the overcurrent protection circuit further includes:

[0033] Main control circuit;

[0034] a discharge circuit, wherein a first end of the discharge circuit is electrically connected to a second end of the first switch branch, and a second end of the discharge circuit is grounded;

[0035] The main control circuit is used to control the discharge circuit to discharge the voltage at the second end of the first switch branch.

[0036] Optionally, the discharge circuit includes:

[0037] A first optocoupler device, wherein the first optocoupler device comprises a primary side and a secondary side, a first end of the primary side of the first optocoupler device is electrically connected to the main control circuit, and a second end of the primary side of the first optocoupler device is grounded;

[0038] A second voltage-dividing circuit, wherein a first end of the second voltage-dividing circuit is electrically connected to a second end of the first switch branch, a second end of the second voltage-dividing circuit is grounded, and the second voltage-dividing circuit is electrically connected to a secondary side of the first optocoupler device.

[0039] Optionally, the overcurrent protection circuit includes:

[0040] A second optocoupler device, wherein the second optocoupler device includes a primary side and a secondary side, wherein the first end of the primary side of the second optocoupler device is electrically connected to the main control circuit, the second end of the primary side of the second optocoupler device is grounded, and the secondary side of the second optocoupler device is electrically connected to the first voltage divider circuit.

[0041] Optionally, the second voltage divider circuit includes:

[0042] a third voltage-dividing resistor, wherein a first end of the third voltage-dividing resistor is electrically connected to a second end of the first switch branch, and a second end of the third voltage-dividing resistor is electrically connected to a first end of a secondary side of the first optocoupler device;

[0043] A fourth voltage-dividing resistor, wherein a first end of the fourth voltage-dividing resistor is electrically connected to a second end of the third voltage-dividing resistor, and a second end of the fourth voltage-dividing resistor is electrically connected to a second end of a secondary side of the first optocoupler device.

[0044] Optionally, the overcurrent protection circuit further includes:

[0045] a third optocoupler device, the third optocoupler device comprising a primary side and a secondary side, the primary side of the third optocoupler device being electrically connected to the main control circuit, and the secondary side of the third optocoupler device being electrically connected to the switch device;

[0046] The main control circuit is also used to output a control signal to the switching device via the third optocoupler device when it is detected that the voltage across the secondary side of the first optocoupler device is less than a preset second voltage value, so as to control the switching device to be in an on state and to conduct the path between the load and the power input terminal.

[0047] The utility model also provides a control chip, wherein the control chip comprises any one of the overcurrent protection circuits described above.

[0048] The utility model proposes an overcurrent protection circuit, which is applied to an IO control circuit. The IO control circuit includes a power input terminal, a load and a switch device arranged in series between the power input terminal and the load, and is electrically connected. The overcurrent protection circuit includes a shunt, a first switch circuit and a second switch circuit. The first end of the shunt is electrically connected to the power input terminal, and the second end of the shunt is electrically connected to the switch device; the first end of the first switch circuit is electrically connected to the power input terminal, and the second end of the first switch circuit is electrically connected to the second end of the shunt; the first end of the second switch circuit is electrically connected to the third end of the first switch circuit, and the second end of the second switch circuit is grounded; the first switch circuit is used to work when the voltage drop on the shunt reaches a preset voltage value to output a first shutdown signal to the controlled end of the switch device to control the switch device to disconnect the path between the load and the power input terminal; the second switch circuit is used to output a second shutdown signal when it is in a disconnected state to put the first switch circuit in a disconnected state.

[0049] In practical applications, when the voltage drop on the shunt reaches a preset voltage value, the first switch circuit outputs a first shutdown signal to control the switch device to disconnect the path between the load and the power input terminal, so as to prevent large currents from damaging the electronic components or loads in the circuit, so as to protect the electronic components and the load from overcurrent. In addition, when the second switch circuit is in the off state, the second shutdown signal is output to control the first switch circuit to be in the off state. For example, when the load is no longer in an overcurrent fault, the second shutdown signal can be output to shut down the first switch circuit, that is, the working state of the first switch circuit no longer affects the path between the load and the power input terminal, so as to facilitate the next protection work. In this way, overcurrent protection is achieved for the load and the electronic components when the load is overcurrent, and the reliability and safety of the overcurrent protection circuit of the utility model are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0051] Figure 1 A schematic diagram of a circuit module of an embodiment of an overcurrent protection circuit of the utility model;

[0052] Figure 2 A schematic diagram of a circuit module of another embodiment of the overcurrent protection circuit of the utility model;

[0053] Figure 3A schematic diagram of a circuit module of another embodiment of the overcurrent protection circuit of the utility model;

[0054] Figure 4 This is a circuit module schematic diagram of another embodiment of the overcurrent protection circuit of the utility model;

[0055] Figure 5 A schematic diagram of a circuit module of an embodiment of an overcurrent protection circuit of the utility model;

[0056] Figure 6 The figure is a specific circuit diagram of an embodiment of the overcurrent protection circuit of the utility model.

[0057] Description of Figure Numbers:

[0058]

[0059] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0060] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0061] In addition, in the present utility model, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0062] The utility model proposes an overcurrent protection circuit, referring to Figure 1 , applied to an IO control circuit, the IO control circuit includes a power input terminal 10, a load and a switch device arranged in series between the power input terminal 10 and the load, and the overcurrent protection circuit includes:

[0063] A shunt 20, wherein a first end of the shunt 20 is electrically connected to the power input terminal 10, and a second end of the shunt 20 is electrically connected to the switch device;

[0064] A first switch circuit 30, wherein a first end of the first switch circuit 30 is electrically connected to the power input end 10, and a second end of the first switch circuit 30 is electrically connected to a second end of the shunt 20;

[0065] A second switch circuit 40, wherein a first end of the second switch circuit 40 is electrically connected to a third end of the first switch circuit 30, and a second end of the second switch circuit 40 is grounded;

[0066] The first switch circuit 30 is used to work when the voltage drop on the shunt 20 reaches a preset voltage value to output a first shutdown signal to the controlled end of the switch device to control the switch device to disconnect the path between the load and the power input terminal 10;

[0067] The second switch circuit 40 is used for outputting a second shut-down signal to keep the first switch circuit 30 in the off state when in the off state.

[0068] In this embodiment, the shunt 20 can be implemented by a resistor shunt 20, a capacitor shunt 20, or an inductor shunt 20. The first switch circuit 30 and the second switch circuit 40 can be implemented by switch devices such as relays and contactors, or switch tubes such as MOS tubes, IGBT tubes, thyristors, and triodes.

[0069] Specifically, refer to Figure 6, VDD is the power input terminal 10, which is used to connect to the 25V power supply voltage. The first end of the shunt 20 is electrically connected to the power input terminal 10, the second end of the shunt 20 is electrically connected to the first end of the switch device, and the second end of the switch device is electrically connected to the load. The shunt 20 is used to detect the current flowing through the load when the switch device is in the on state. The first switch circuit 30 is electrically connected to the shunt 20, and works when the voltage drop on the shunt 20 reaches a preset voltage value to output a first shutdown signal to the controlled end of the switch device to control the switch device to disconnect the path between the load and the power input terminal 10; in addition, the second switch circuit 40 is electrically connected to the first switch circuit 30, and the second switch circuit 40 can be in the off state when receiving an external control signal to output a second shutdown signal, so that the first switch circuit 30 is in the off state, thereby ensuring that the first switch circuit 30 no longer outputs the first shutdown signal to the switch device, so that the working state of the first switch circuit 30 will no longer affect the path between the load and the power input terminal 10. Among them, the preset voltage value is set in advance by the R&D personnel, and the external control signal can be the control signal output by the main controller, such as the main controller MCU, DSP (Digital Signal Process), FPGA (Field Programmable Gate Array), PLC, SOC (System On Chip), etc.

[0070] In practical applications, when the voltage drop on the shunt 20 reaches a preset voltage value, the first switch circuit 30 outputs a first shutdown signal to control the switch device to disconnect the path between the load and the power input terminal 10, so as to avoid large current from damaging the electronic components or load in the circuit, so as to protect the electronic components and the load from overcurrent. In addition, when the second switch circuit 40 is in the off state, it outputs a second shutdown signal to control the first switch circuit 30 to be in the off state. For example, when the load is no longer in an overcurrent fault, the second shutdown signal can be output to turn off the first switch circuit 30, that is, the working state of the first switch circuit 30 no longer affects the path between the load and the power input terminal 10, so as to facilitate the next protection work. In this way, overcurrent protection of the load and electronic components is achieved when the load is overcurrent, and the reliability and safety of the overcurrent protection circuit of the utility model are improved.

[0071] In another embodiment of the present invention, reference Figure 2 , the first switch circuit 30 includes:

[0072] A first switch branch 31, wherein a first end of the first switch branch 31 is electrically connected to the power input terminal 10, and a third end of the first switch branch 31 is electrically connected to the switch device;

[0073] The second switch branch 32 , wherein a first end of the second switch branch 32 is electrically connected to a second end of the first switch branch 31 , and a second end of the second switch branch 32 is electrically connected to the second switch circuit 40 .

[0074] Wherein, the first switch branch 31 includes:

[0075] A first switching tube;

[0076] A first resistor, wherein a first end of the first resistor is electrically connected to a first end of the first switch tube and a first end of the shunt 20 respectively, and a second end of the first resistor is electrically connected to a second end of the first switch tube;

[0077] a second resistor, wherein a first end of the second resistor is electrically connected to a second end of the first resistor, and a second end of the second resistor is electrically connected to a second end of the shunt 20;

[0078] A first capacitor, wherein a first end of the first capacitor is electrically connected to a first end of the first resistor, and a second end of the first capacitor is electrically connected to a second end of the first resistor.

[0079] A unidirectional conducting circuit, wherein a first end of the unidirectional conducting circuit is electrically connected to the third end of the first switch tube, and a second end of the unidirectional conducting circuit is electrically connected to the controlled end of the switch device.

[0080] The second switch branch 32 comprises:

[0081] a second switch tube, wherein a first end of the second switch tube is electrically connected to a second end of the first switch tube, and a second end of the second switch tube is electrically connected to a third end of the first switch tube;

[0082] a third resistor, wherein a first end of the third resistor is electrically connected to the second end of the second switch tube, and a second end of the third resistor is electrically connected to the third end of the second switch tube;

[0083] A fourth resistor, wherein a first end of the fourth resistor is electrically connected to a second end of the third resistor, and a second end of the fourth resistor is electrically connected to the second switch circuit 40 .

[0084] In this embodiment, the first switch tube and the second switch tube can be implemented by the above-mentioned MOS tube, IGBT tube, thyristor, triode and other switch tubes. The unidirectional conduction circuit can be implemented by diodes, switch tubes with body diodes such as MOS tubes.

[0085] refer to Figure 6, PNP transistor Q1 is the first switch tube, R1 is the first resistor, R2 is the second resistor, C1 is the first capacitor, diode D1 is a unidirectional conduction circuit, NPN transistor Q2 is the second switch tube, R3 is the third resistor, and R4 is the fourth resistor. In this embodiment, the switch device is a P-type MOS tube. Among them, the emitter e of Q1 is connected to the first end of the first resistor R1, the base b of Q1 is electrically connected to the second end of the first resistor R1, the first end of the second resistor R2 is electrically connected to the second end of the first resistor R1, and the second end of the second resistor R2 is electrically connected to the second end of the shunt 20. That is, the voltage on the shunt 20 will act on the base and emitter of Q1 after being divided by R1 and R2 connected in series, the base of the second switch tube Q2 is electrically connected to the collector of the first switch tube Q1, the collector of the second switch tube Q2 is electrically connected to the base of the first switch tube, and the emitter of the second switch tube is electrically connected to the second end of the third resistor.

[0086] Specifically, as the voltage drop on R1 increases, Q1 is turned on, that is, when the load is overcurrent, the current generates a voltage difference from the power input terminal 10VDD through the shunt 20. When the voltage drop on the shunt 20 reaches the preset voltage value, Q1 is turned on, and the current passes through the emitter e and the collector c of Q1 to reach the base of Q2. The third resistor R3 and the fourth resistor R4 are a resistor voltage divider circuit. The voltage across R3 can cause a voltage difference between the base of Q2 and the ground, which will cause Q2 to be turned on. At the same time, since the voltage at point a is 24V after Q1 is turned on, the unidirectional conduction circuit diode D1 is turned on, and the gate-source voltage of the switching device is close to 0, so the switching device is disconnected. In this way, the path between the load and the power input terminal 10VDD is in a disconnected state, which can effectively protect the load when a load overcurrent fault occurs. It should be noted that when Q1 and Q2 are turned on, the current flows from VDD to the collector c of Q1, then through the emitter e of Q1 to the base b and emitter e of Q2, and then through the fourth resistor R4 to the second switch circuit 40. In addition, the second switch circuit 40 needs to be in the on state when the load does not have an overcurrent fault, so that when the load is overcurrent, the first switch tube Q1 and the second switch tube Q2 are turned on to bypass the branch where the load is located, so as to protect the load.

[0087] It should be understood that when the current on the load returns to normal, that is, the voltage drop on the shunt 20 is lower than the preset voltage value, a corresponding voltage detection circuit can be set to detect the voltage on the shunt 20 and output a corresponding detection signal to put the second switch circuit 40 in an off state, that is, output a second off signal to put the first switch circuit 30 in an off state, that is, the working state of the first switch circuit 30 no longer affects the path between the load and the power input terminal 10, so as to facilitate the next protection work.

[0088] Through the above arrangement, overcurrent protection is achieved for the load and electronic components in the circuit when the load is overcurrent through simple electronic components such as transistors, resistors, capacitors, etc., which improves the reliability and safety of the overcurrent protection circuit of the utility model and reduces the design cost of the circuit.

[0089] In another embodiment of the present invention, reference Figure 3 , the second switch circuit 40 includes:

[0090] A first voltage divider circuit 41, wherein a first end of the first voltage divider circuit 41 is electrically connected to the power input terminal 10, and a second end of the first voltage divider circuit 41 is grounded;

[0091] A third switch branch 42, wherein a first end of the third switch branch 42 is electrically connected to a second end of the second switch branch 32, a second end of the third switch branch 42 is electrically connected to the first voltage divider circuit 41, and a third end of the third switch branch 42 is grounded.

[0092] The first voltage divider circuit 41 comprises:

[0093] a first voltage-dividing resistor, wherein a first end of the first voltage-dividing resistor is electrically connected to the power input terminal 10, and a second end of the first voltage-dividing resistor is electrically connected to a second end of the third switch branch 42;

[0094] A second voltage-dividing resistor, wherein a first end of the second voltage-dividing resistor is electrically connected to a second end of the first voltage-dividing resistor, and a second end of the second voltage-dividing resistor is electrically connected to a third end of the third switch branch 42 .

[0095] The third switch branch 42 includes:

[0096] A third switch tube, wherein a first end of the third switch tube is electrically connected to a second end of the second switch branch 32 , a second end of the third switch tube is electrically connected to a second end of the first voltage-dividing resistor, and a third end of the third switch tube is grounded.

[0097] In this embodiment, the first voltage divider circuit 41 can be implemented by a voltage divider circuit composed of components such as resistors, capacitors, diodes, and transistors, and the third switch branch 42 can be implemented by switching devices such as contactors and relays mentioned above, or switching tubes such as transistors, MOS tubes, and IGBT tubes.

[0098] The first voltage divider circuit 41 is described as a voltage divider circuit composed of two resistors connected in series. Figure 6, R5 is a first voltage-dividing resistor, R6 is a second voltage-dividing resistor, and the N-type MOS tube Q3 is a third switch tube. Among them, the drain D of the N-type MOS tube Q3 is electrically connected to the second end of the fourth resistor R4, the gate G of the N-type MOS tube is electrically connected to the common connection end of the first voltage-dividing resistor R5 and the second voltage-dividing resistor R6, the source S of the N-type MOS tube is electrically connected to the second end of the second voltage-dividing resistor R6, and the second voltage-dividing resistor R6 is grounded via a diode D6. The diode D6 is an anti-reverse connection circuit to prevent damage to the electronic components in the circuit when the power input terminal 10VDD is connected to a power supply voltage with opposite polarity.

[0099] Specifically, during normal operation, due to the voltage-dividing effect of the first voltage-dividing resistor R5 and the second voltage-dividing resistor R6, when the voltage on R6 reaches the on-voltage of the gate-source of the third switch tube Q3, Q3 is turned on. In this embodiment, VDD is a 24V power supply voltage, so the initial state of Q3 is the on-state. Combined with the above-mentioned embodiments, when the voltage drop on the shunt 20 reaches a preset voltage value, the first switch tube Q1 is turned on, and then the second switch tube Q2 is turned on. Therefore, the first switch tube Q1, the second switch tube Q2, the fourth resistor R4, the third switch tube Q3 and the first voltage-dividing resistor R5 and the second voltage-dividing resistor R6 form a self-locking loop. In this way, when the voltage difference formed by the shunt 20 reaches the on-voltage of Q1, the 24V power supply voltage connected to the power input terminal 10VDD will be from Q1's ce to point a, that is, the voltage difference between the base and emitter of Q2 will make Q2 turn on, and then Q2ce is also in a closed state, and the voltage at point a will be maintained. The voltage of point a is maintained at 24V, and 24V passes through the emitter and base of Q1 to the collector and emitter of Q2, and then passes through R4 and Q3 to the ground. In this way, when the shunt 20 is overcurrent, since the voltage at point a is 24V, the diode D1 is turned on to turn off the switch device. The setting of the second switch tube can ensure that after Q1 is turned on when the load is overcurrent, even if the voltage drop on the shunt 20 drops to below the preset voltage value, Q1 is still in the on state, and the voltage at point a is still maintained at 24V. D1 is turned on to output the first shutdown signal, so that the gate-source voltage of the switch device is close to 0V, realizing hardware protection locking, and the circuit forms a self-locking loop for overcurrent protection.

[0100] It should be noted that, in combination with the contents of the above embodiments, when the current on the load returns to a normal value, that is, the voltage drop on the shunt 20 is lower than the preset voltage value, a corresponding voltage detection circuit can be set to detect the voltage on the shunt 20 and output a corresponding detection signal to put the second switch circuit 40 in an off state, that is, Q3 is in an off state, the self-locking circuit is disconnected, and it returns to a normal working state, so as to facilitate the next overcurrent protection work.

[0101] Through the above arrangement, a self-locking loop is formed by the first voltage divider circuit 41, the first switch tube, the second switch tube and the third switch tube to perform hardware protection when an overcurrent fault occurs in the load, thereby improving the reliability of the overcurrent protection circuit of the utility model.

[0102] In another embodiment of the present invention, reference Figure 4 and Figure 5 , the overcurrent protection circuit also includes:

[0103] Main control circuit 50;

[0104] A discharge circuit 60, wherein a first end of the discharge circuit 60 is electrically connected to a second end of the first switch branch 31, and a second end of the discharge circuit 60 is grounded;

[0105] The main control circuit 50 is used to control the discharge circuit 60 to discharge the voltage at the second end of the first switch branch 31 .

[0106] The second optocoupler device 70 includes a primary side and a secondary side, the first end of the primary side of the second optocoupler device 70 is electrically connected to the main control circuit 50, the second end of the primary side of the second optocoupler device 70 is grounded, and the secondary side of the second optocoupler device 70 is electrically connected to the first voltage divider circuit 41.

[0107] Wherein, the discharge circuit 60 includes:

[0108] A first optocoupler device 61, wherein the first optocoupler device 61 includes a primary side and a secondary side, wherein a first end of the primary side of the first optocoupler device 61 is electrically connected to the main control circuit 50, and a second end of the primary side of the first optocoupler device 61 is grounded;

[0109] A second voltage divider circuit 62 , wherein a first end of the second voltage divider circuit 62 is electrically connected to a second end of the first switch branch 31 , a second end of the second voltage divider circuit 62 is grounded, and the second voltage divider circuit 62 is electrically connected to a secondary side of the first optocoupler device 61 .

[0110] In this embodiment, the main control circuit 50 can be implemented by the main controller described above. The second voltage-dividing circuit 62 is implemented by a voltage-dividing circuit composed of components such as resistors, capacitors, diodes, and transistors. This embodiment selects a third voltage-dividing resistor and a fourth voltage-dividing resistor connected in series as the second voltage-dividing circuit 62, wherein the first end of the third voltage-dividing resistor is electrically connected to the second end of the first switch branch 31, and the second end of the third voltage-dividing resistor is electrically connected to the first end of the secondary side of the first optocoupler device 61; the first end of the fourth voltage-dividing resistor is electrically connected to the second end of the third voltage-dividing resistor, and the second end of the fourth voltage-dividing resistor is electrically connected to the second end of the secondary side of the first optocoupler device 61.

[0111] Specifically, U1 is the first optocoupler 61, U2 is the second optocoupler 70, R7 is the third voltage-dividing resistor, R8 is the fourth voltage-dividing resistor, and the main control circuit 50 is used to detect the OVER_DETECT signal. When operating normally, Q1 is in the off state, and the voltage at point a is 0V. When an overcurrent fault occurs in the load, Q1 is turned on and the voltage at point a is 24V. Therefore, the main control circuit 50 can detect the corresponding OVER_DETECT signal according to the first optocoupler 61. For example, when the secondary side of the first optocoupler 61U1 is in an open circuit state, when the external amplifying resistor is electrically connected to the power supply end of the main control circuit 50, that is, it is 3.3V in normal operation, at this time, the OVER_DETECT signal is a high-level signal. When the load is overcurrent, that is, the voltage at point a is 24V, the secondary side of U1 is connected to the 24V voltage, and the secondary side is grounded, so the voltage is 0V, and at this time, the OVER_DETECT signal is a low-level signal. Therefore, the main control circuit 50 can determine whether the load is in an overcurrent fault according to the voltage jump state of the OVER_DETECT signal. If the main control circuit 50 determines that the load overcurrent fault is relieved according to the OVER_DETECT signal, it outputs a SWITCH signal to the second optocoupler device 70. This signal is a pulse signal. Q3 is first turned off and then turned on. When it is turned off, the hardware protection of the self-locking loop does not work. The voltage at point a needs to drop from 24V to 0V. Therefore, the voltage at point a is discharged through the third voltage-dividing resistor R7 and the fourth voltage-dividing resistor R8 until the voltage at point a is reduced to 0V, so that the diode D1 cannot be turned on, that is, the first switch circuit 30 no longer outputs the first shutdown signal to control the switch device to disconnect the path between the load and the power input terminal 10. In this way, it can prepare for the next overcurrent protection work. That is, when the load voltage drop is greater than the preset voltage value, the first switch tube Q1 is turned on, and the diode D1 is turned on to output the first shutdown signal to turn off the switch device. After Q1 is turned on, the second switch tube Q2 is turned on, forming a self-locking loop composed of the first voltage-dividing circuit 41, the first switch tube, the second switch tube, and the third switch tube, and entering hardware protection.

[0112] Through the above-mentioned setting, the main control circuit 50 and the first optocoupler device 61 can detect the overcurrent fault of the shunt 20, so that when the overcurrent fault of the shunt 20 is relieved, the corresponding control signal is output to make the second switch circuit 40 in the off state, and the second off signal is output to make the first switch circuit 30 in the off state, thereby releasing the hardware protection process. In addition, the setting of the discharge circuit 60 can restore the overcurrent protection circuit of the utility model to the initial state to perform the next overcurrent protection work. The setting of the first optocoupler device 61 and the second optocoupler device 70 effectively isolates the input end signal and the output end signal, thereby reducing the interference effect of the signal in the circuit and improving the reliability and stability of the overcurrent protection circuit of the utility model.

[0113] In another embodiment of the present invention, the overcurrent protection circuit further includes:

[0114] A third optocoupler device 80, wherein the third optocoupler device 80 includes a primary side and a secondary side, the primary side of the third optocoupler device 80 is electrically connected to the main control circuit 50, and the secondary side of the third optocoupler device 80 is electrically connected to the switch device;

[0115] The main control circuit 50 is also used to output a control signal to the switching device via the third optocoupler device 80 when it is detected that the voltage across the secondary side of the first optocoupler device 61 is less than a preset second voltage value, so as to control the switching device to be in the on state and to turn on the path between the load and the power input terminal 10.

[0116] refer to Figure 6 , U3 is the third optocoupler device 80. When working normally, the main control circuit 50 outputs the CONTROL_IO signal to the third optocoupler device 80, wherein the CONTROL_IO signal is a high-level signal. Due to the voltage-dividing effect of R11 and R12, the gate-source voltage of the switching device reaches the on-voltage of the switching device and is in the on-state, thereby opening the channel between the power input terminal 10 and the load.

[0117] Specifically, the current flowing through the load is I, then the voltage drop across the shunt 20 is U=I*R3;

[0118] Then the voltage between the base and emitter of the first switch tube Q1 is:

[0119] ;

[0120] When the conduction voltage of Q1 is reached, Q1 is turned on, and the switch device is closed by the unidirectional conduction circuit D1, and the hardware protection process begins; the main control circuit 50 pulls down the CONTROL_IO signal; at this time, the voltage at point a changes from 0 to a high level, and the state of the OVER_DETECT signal will jump. The main control circuit 50 detects the OVER_DETECT signal and outputs the SWITCH signal, which is a pulse signal. Q3 is first turned off and then turned on. When it is turned off, the hardware protection process is contacted, and the voltage at point a becomes 0V after discharge, and no longer affects the working state of the switch device through the diode D1, and the overall circuit returns to the initial state; when the main control circuit 50 detects that the voltage at both ends of the secondary side of the first optocoupler device 61 is less than the preset second voltage value, the third optocoupler device 80 outputs a control signal to the switch device to control the switch device to be in the on state, and to turn on the path between the load and the power input terminal 10. Among them, the preset second voltage value is set in advance by the R&D personnel. When the voltage at point a is 0V, the main control circuit 50 outputs the control signal CONTROL_IO. At this time, CONTROL_IO is a high-level signal, the switch device is turned on, and the circuit resumes normal operation. If an overcurrent fault occurs again in the shunt 20, the above working process will be repeated to form a self-locking loop for hardware protection until the current on the load returns to normal and is released by software by the main control circuit 50.

[0121] Through the above settings, hardware protection can be implemented when an overcurrent fault occurs in the load, until the load current returns to normal, the hardware protection mechanism is released by software, and restored to the initial state to perform the next overcurrent protection work. The overcurrent protection is performed by combining software and hardware, which further improves the reliability of the overcurrent protection circuit of the utility model. In addition, the overcurrent protection circuit of the utility model can be implemented by simple electronic components, which reduces the design cost of the circuit to a certain extent.

[0122] The utility model also provides a control chip, wherein the control chip comprises any one of the overcurrent protection circuits described above.

[0123] It is worth noting that since the control chip of the utility model is based on the above-mentioned overcurrent protection circuit, the embodiments of the control chip of the utility model include all technical solutions of all embodiments of the above-mentioned overcurrent protection circuit, and the technical effects achieved are also exactly the same, which will not be repeated here.

[0124] The above description is only an optional embodiment of the utility model, and does not limit the patent scope of the utility model. All equivalent structural changes made by using the contents of the utility model specification and drawings under the inventive concept of the utility model, or direct / indirect application in other related technical fields are included in the patent protection scope of the utility model.

Claims

1. An overcurrent protection circuit, applied to an IO control circuit, the IO control circuit comprising a power input terminal, a load and a switch device arranged in series between the power input terminal and the load, characterized in that: The overcurrent protection circuit comprises: A shunt, wherein a first end of the shunt is electrically connected to a power input end, and a second end of the shunt is electrically connected to the switch device; a first switch circuit, wherein a first end of the first switch circuit is electrically connected to the power input end, and a second end of the first switch circuit is electrically connected to the second end of the shunt; a second switch circuit, wherein a first end of the second switch circuit is electrically connected to a third end of the first switch circuit, and a second end of the second switch circuit is grounded; The first switch circuit is used to operate when the voltage drop on the shunt reaches a preset voltage value to output a first shutdown signal to the controlled end of the switch device to control the switch device to disconnect the path between the load and the power input end; The second switch circuit is used to output a second shutdown signal to put the first switch circuit in an off state when the second switch circuit is in an off state.

2. The overcurrent protection circuit according to claim 1, characterized in that: The first switch circuit comprises: a first switch branch, wherein a first end of the first switch branch is electrically connected to a power input end, and a third end of the first switch branch is electrically connected to the switch device; A second switch branch, wherein a first end of the second switch branch is electrically connected to a second end of the first switch branch, and a second end of the second switch branch is electrically connected to the second switch circuit.

3. The overcurrent protection circuit according to claim 2, characterized in that: The first switch branch comprises: A first switching tube; a first resistor, wherein a first end of the first resistor is electrically connected to a first end of the first switch tube and a first end of the shunt, respectively, and a second end of the first resistor is electrically connected to a second end of the first switch tube; a second resistor, wherein a first end of the second resistor is electrically connected to a second end of the first resistor, and a second end of the second resistor is electrically connected to a second end of the shunt; A first capacitor, wherein a first end of the first capacitor is electrically connected to a first end of the first resistor, and a second end of the first capacitor is electrically connected to a second end of the first resistor.

4. The overcurrent protection circuit according to claim 3, characterized in that: The first switch branch further includes: A unidirectional conducting circuit, wherein a first end of the unidirectional conducting circuit is electrically connected to the third end of the first switch tube, and a second end of the unidirectional conducting circuit is electrically connected to the controlled end of the switch device.

5. The overcurrent protection circuit according to claim 3, characterized in that: The second switch branch comprises: a second switch tube, wherein a first end of the second switch tube is electrically connected to a second end of the first switch tube, and a second end of the second switch tube is electrically connected to a third end of the first switch tube; a third resistor, wherein a first end of the third resistor is electrically connected to the second end of the second switch tube, and a second end of the third resistor is electrically connected to the third end of the second switch tube; A fourth resistor, wherein a first end of the fourth resistor is electrically connected to a second end of the third resistor, and a second end of the fourth resistor is electrically connected to the second switch circuit.

6. The overcurrent protection circuit according to claim 2, characterized in that: The second switch circuit comprises: a first voltage divider circuit, wherein a first end of the first voltage divider circuit is electrically connected to the power input end, and a second end of the first voltage divider circuit is grounded; A third switch branch, wherein a first end of the third switch branch is electrically connected to a second end of the second switch branch, a second end of the third switch branch is electrically connected to the first voltage divider circuit, and a third end of the third switch branch is grounded.

7. The overcurrent protection circuit according to claim 6, characterized in that: The first voltage divider circuit comprises: a first voltage-dividing resistor, wherein a first end of the first voltage-dividing resistor is electrically connected to the power input end, and a second end of the first voltage-dividing resistor is electrically connected to the second end of the third switch branch; A second voltage-dividing resistor, wherein a first end of the second voltage-dividing resistor is electrically connected to a second end of the first voltage-dividing resistor, and a second end of the second voltage-dividing resistor is electrically connected to a third end of the third switch branch.

8. The overcurrent protection circuit according to claim 7, characterized in that: The third switch branch comprises: A third switch tube, wherein a first end of the third switch tube is electrically connected to a second end of the second switch branch, a second end of the third switch tube is electrically connected to a second end of the first voltage-dividing resistor, and a third end of the third switch tube is grounded.

9. The overcurrent protection circuit according to claim 6, characterized in that: The overcurrent protection circuit further includes: Main control circuit; a discharge circuit, wherein a first end of the discharge circuit is electrically connected to a second end of the first switch branch, and a second end of the discharge circuit is grounded; The main control circuit is used to control the discharge circuit to discharge the voltage at the second end of the first switch branch.

10. The overcurrent protection circuit according to claim 9, characterized in that: The discharge circuit comprises: A first optocoupler device, wherein the first optocoupler device comprises a primary side and a secondary side, a first end of the primary side of the first optocoupler device is electrically connected to the main control circuit, and a second end of the primary side of the first optocoupler device is grounded; A second voltage-dividing circuit, wherein a first end of the second voltage-dividing circuit is electrically connected to a second end of the first switch branch, a second end of the second voltage-dividing circuit is grounded, and the second voltage-dividing circuit is electrically connected to a secondary side of the first optocoupler device.

11. The overcurrent protection circuit according to claim 10, characterized in that: The overcurrent protection circuit comprises: A second optocoupler device, wherein the second optocoupler device includes a primary side and a secondary side, wherein the first end of the primary side of the second optocoupler device is electrically connected to the main control circuit, the second end of the primary side of the second optocoupler device is grounded, and the secondary side of the second optocoupler device is electrically connected to the first voltage divider circuit.

12. The overcurrent protection circuit according to claim 10, characterized in that: The second voltage divider circuit comprises: a third voltage-dividing resistor, wherein a first end of the third voltage-dividing resistor is electrically connected to a second end of the first switch branch, and a second end of the third voltage-dividing resistor is electrically connected to a first end of a secondary side of the first optocoupler device; A fourth voltage-dividing resistor, wherein a first end of the fourth voltage-dividing resistor is electrically connected to a second end of the third voltage-dividing resistor, and a second end of the fourth voltage-dividing resistor is electrically connected to a second end of a secondary side of the first optocoupler device.

13. The overcurrent protection circuit according to any one of claims 10 to 12, characterized in that: The overcurrent protection circuit further includes: a third optocoupler device, the third optocoupler device comprising a primary side and a secondary side, the primary side of the third optocoupler device being electrically connected to the main control circuit, and the secondary side of the third optocoupler device being electrically connected to the switch device; The main control circuit is also used to output a control signal to the switching device via the third optocoupler device when it is detected that the voltage across the secondary side of the first optocoupler device is less than a preset second voltage value, so as to control the switching device to be in an on state and to conduct the path between the load and the power input terminal.

14. A control chip, characterized in that: The control chip includes the overcurrent protection circuit as described in any one of claims 1-13.

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