Constant voltage and constant current short circuit protection device and power supply system

Abstract

The utility model relates to power protection technical field discloses a kind of constant voltage constant current short-circuit protection device, comprising: power transmission end, reference sampling circuit, first voltage sampling circuit, first current sampling circuit, first optocoupler and comparison control chip.Reference sampling circuit is used to export voltage reference value and current reference value to comparison control chip;First voltage sampling circuit is used to export first voltage sampling value to comparison control chip;First current sampling circuit is used to export first current sampling value to comparison control chip;Comparison control chip is connected with first optocoupler, comparison control chip is used to export short-circuit signal to first optocoupler when determining that first voltage sampling value is lower than the voltage reference value, and first current sampling value is higher than current reference value;The model of comparison control chip is TSM104 chip.Can be combined with the double conditions of voltage and current, the accurate identification to real short-circuit fault is realized.

Description

Technical Field

[0001] This utility model relates to the field of power protection technology, and in particular to a constant voltage and constant current short circuit protection device and power system. Background Technology

[0002] In existing technology, after a power supply is connected to an external load, if the external power supply line is too thin, resulting in significant non-zero resistance, and the power supply's internal resistance is not particularly large, and a large initiation current is generated during startup, then the initiation current will cause a significant voltage drop across the non-zero resistance and the power supply's internal resistance. This may lead to a sudden drop in output voltage, even below the normal operating voltage or protection threshold. If the initiation current itself exceeds the power supply's short-circuit detection threshold, or if the voltage drop triggers other protection mechanisms, it is very likely that the power supply's protection circuit will mistakenly identify it as a short circuit. Utility Model Content

[0003] The purpose of this utility model is to provide a constant voltage and constant current short circuit protection device and power supply system to solve one or more technical problems existing in the prior art, and at least provide a beneficial option or create conditions.

[0004] To achieve the above objectives, one embodiment of this application provides a constant voltage and constant current short circuit protection device, which includes: a power transmission terminal, a reference sampling circuit, a first voltage sampling circuit, a first current sampling circuit, a first optocoupler, and a comparison control chip;

[0005] The input terminals of the reference sampling circuit, the first voltage sampling circuit, and the first current sampling circuit are all connected to the power transmission terminal.

[0006] The output terminal of the reference sampling circuit is connected to the reference port of the comparison control chip, and the reference sampling circuit is used to output voltage reference value and current reference value to the comparison control chip;

[0007] The output terminal of the first voltage sampling circuit is connected to the voltage comparison port of the comparison control chip, and the first voltage sampling circuit is used to output a first voltage sample value to the comparison control chip.

[0008] The output terminal of the first current sampling circuit is connected to the current comparison port of the comparison control chip, and the first current sampling circuit is used to output a first current sampling value to the comparison control chip.

[0009] The comparison control chip is connected to the first optocoupler. The comparison control chip is used to output a short-circuit signal to the first optocoupler when it is determined that the first voltage sample value is lower than the voltage reference value and the first current sample value is higher than the current reference value.

[0010] The comparison control chip is a TSM104 chip.

[0011] Furthermore, the constant voltage and constant current short circuit protection device also includes: a power supply terminal, a selection circuit, a second optocoupler, a second current sampling circuit, and a second voltage sampling circuit;

[0012] The input terminals of the second voltage sampling circuit and the second current sampling circuit are connected to the power supply terminal.

[0013] The output terminal of the second voltage sampling circuit is connected to the constant voltage control port of the comparison control chip, and the second voltage sampling circuit is used to output the second voltage sampling value to the comparison control chip;

[0014] The output terminal of the second current sampling circuit is connected to the constant current control port of the comparison control chip, and the second current sampling circuit is used to output the second current sampling value to the comparison control chip.

[0015] The second optocoupler is connected to the comparison control chip through the selection circuit. The comparison control chip is also used to output a control signal to the second optocoupler when it is determined that the second voltage sample value is higher than the voltage reference value or the second current sample value is higher than the current reference value.

[0016] Furthermore, the constant voltage and constant current short circuit protection device also includes: a first pull-up resistor, a first diode, and a first pull-down circuit;

[0017] The first pull-up resistor is connected to the anode of the light-emitting diode of the first optocoupler and the first output terminal of the comparator control chip, respectively.

[0018] The anode of the first diode is connected to the cathode of the light-emitting diode of the first optocoupler, the cathode of the first diode is connected to the second output terminal of the comparator control chip, and the first pull-down circuit is connected to the second output terminal of the comparator control chip and the power transmission terminal, respectively.

[0019] Furthermore, the selection circuit includes: a second diode, a third diode, and a second pull-down circuit;

[0020] The anodes of the second diode and the third diode are both connected to the cathode of the light-emitting diode of the second optocoupler. The cathode of the second diode is connected to the third output terminal of the comparator control chip, and the cathode of the third diode is connected to the fourth output terminal of the comparator control chip. The second pull-down circuit is connected to the third output terminal and the power supply terminal of the comparator control chip, respectively.

[0021] Furthermore, the reference sampling circuit includes: a second pull-up resistor, a first series resistor group, and a second series resistor group;

[0022] The second pull-up resistor is connected to both the power transmission terminal and the reference port of the comparison control chip.

[0023] The first series resistor group is connected to the second pull-up resistor and the reference port of the comparator control chip, respectively;

[0024] The second series resistor group is connected to the second pull-up resistor and the reference port of the comparison control chip, respectively.

[0025] Furthermore, the selection circuit includes: a first pull-up circuit;

[0026] One end of the first pull-up circuit is connected to the fourth output terminal of the comparator control chip and the cathode of the third diode, respectively, and the other end of the first pull-up circuit is connected to the second voltage sampling circuit and the constant voltage control port of the comparator control chip, respectively.

[0027] Furthermore, the anode of the light-emitting diode of the second optocoupler is connected to the power supply terminal.

[0028] Furthermore, the first optocoupler is an LTV-357 optocoupler isolator.

[0029] Furthermore, the second optocoupler is an LTV-357 optocoupler isolator.

[0030] Another embodiment of this application provides a power supply system, including a constant voltage and constant current short circuit protection device provided by an embodiment of this application.

[0031] The beneficial effects of this invention are as follows: A voltage reference value and a current reference value are determined by sampling through a reference sampling circuit. A first voltage sample value and a first current sample value are obtained by sampling the transmission terminal. When the first voltage sample value is lower than the voltage reference value and the first current sample value is higher than the current reference value, a short-circuit signal is output to the first optocoupler, turning on the light-emitting diode in the first optocoupler. This allows the output of the first optocoupler to output a short-circuit signal to the main control circuit in a low-impedance form for short-circuit protection. This effectively distinguishes between short-circuit faults and temporary large currents caused by startup transients or line impedance. Although the startup current may exceed the safety threshold, the protection will not be triggered because the voltage has not yet dropped below the set value, thus avoiding misjudgment. It prevents startup voltage dips caused by line impedance or load characteristics from being misjudged as short circuits, thereby avoiding unnecessary power shutdowns or protection actions, improving power supply availability and system stability. By combining the dual conditions of voltage and current, accurate identification of real short-circuit faults is achieved. Attached Figure Description

[0032] Figure 1This is a schematic diagram of the circuit structure of a constant voltage and constant current short circuit protection device provided in one embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the circuit structure of a power supply system provided in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the frame of a constant voltage and constant current short circuit protection device provided in one embodiment of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and should not be construed as limiting the scope of this invention.

[0036] It should be noted that although the functional circuits are divided in the schematic diagram, in some cases, the circuits can be divided differently from those in the system.

[0037] Furthermore, it is understood that the terms "first," "second," etc., used in this application may be used herein to describe various concepts, but unless specifically stated otherwise, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more features. For example, without departing from the scope of embodiments of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the words "if" or "when" as used herein may be interpreted as "in the event of," "when," or "in response to a determination."

[0038] In the description of this utility model, it should be noted that, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0039] As described in the background section, in the prior art, after a power supply is connected to an external load, if the external power supply line is too thin, resulting in significant non-zero resistance, and the power supply's internal resistance is not particularly large, and a large starting current is generated during startup, then the starting current will cause a significant voltage drop across the non-zero resistance and the power supply's internal resistance. This may cause the output voltage to drop sharply, even below the normal operating voltage or protection threshold. If the starting current itself exceeds the power supply's short-circuit detection threshold, or if the voltage drop triggers other protection mechanisms, it is very likely that the power supply's protection circuit will mistakenly identify it as a short circuit.

[0040] Reference Figure 1 and Figure 3 In some embodiments of this utility model, a constant voltage and constant current short circuit protection device includes: a power transmission terminal, a reference sampling circuit 100, a first voltage sampling circuit 200, a first current sampling circuit 300, a first optocoupler U2, and a comparison control chip U1.

[0041] The input terminal of the reference sampling circuit 100 is electrically connected to the power transmission terminal, and the output terminal of the reference sampling circuit 100 is electrically connected to the reference port of the comparison control chip U1. The reference port of the comparison control chip U1 is the IN+ pin. That is, the output terminal of the reference sampling circuit 100 is connected to the third, fifth, twelfth and fourteenth pins of the comparison control chip U1 respectively. The reference sampling circuit 100 can sample the power transmission terminal to obtain the voltage reference value and the current reference value, and output the voltage reference value and the current reference value to the comparison control chip U1.

[0042] The input terminal of the first voltage sampling circuit 200 is electrically connected to the power transmission terminal, and the output terminal of the first voltage sampling circuit 200 is electrically connected to the voltage comparison port of the comparison control chip U1, that is, electrically connected to the second pin of the comparison control chip U1. The first voltage sampling circuit 200 can sample the power transmission terminal to obtain the first voltage sampling value and output the first voltage sampling value to the comparison control chip U1.

[0043] The input terminal of the first current sampling circuit 300 is electrically connected to the power transmission terminal, and the output terminal of the first current sampling circuit 300 is electrically connected to the current comparison port of the comparison control chip U1, that is, electrically connected to the sixth pin of the comparison control chip U1. The first current sampling circuit 300 can sample the power transmission terminal to obtain the first current sampling value and output the first current sampling value to the comparison control chip U1.

[0044] The comparison control chip U1 is electrically connected to the light-emitting diode of the first optocoupler U2, that is, the first pin of the comparison control chip U1 is electrically connected to the anode of the light-emitting diode of the first optocoupler U2, and the seventh pin of the comparison control chip U1 is electrically connected to the cathode of the light-emitting diode of the first optocoupler U2.

[0045] When the first voltage sample value is lower than the voltage reference value and the first current sample value is higher than the current reference value, the first pin of the comparison control chip U1 outputs a high-level signal and the seventh pin of the comparison control chip U1 outputs a low-level signal. The high-level signal and the low-level signal form an output short-circuit signal, which is output to the first optocoupler U2.

[0046] The comparator control chip U1 is a TSM104 chip. This chip integrates a voltage comparator, a current comparator, a constant current control comparator, and a constant voltage control comparator.

[0047] The output of the first optocoupler U2 is electrically connected to the main control circuit. The first optocoupler U2 receives a high-level signal and a low-level signal to form an output short-circuit signal. The LED in the first optocoupler U2 is turned on, and the output terminal outputs a high-level signal and a low-level signal to the main control circuit in a low-impedance manner, thus providing a control signal to the main circuit. That is, if an output voltage below the set voltage results in a current exceeding the set safe current, this circuit will provide a control signal to the main circuit.

[0048] The first optocoupler U2 is an LTV-357 optocoupler isolator. The first current sampling circuit 300 includes a first voltage divider resistor group RS1, in which the resistors are connected in parallel. Other discrete components may also be included, which will not be described in detail in this embodiment.

[0049] Compared to traditional simple current threshold detection, this application outputs a short-circuit signal to the first optocoupler U2 when the first voltage sample value is lower than the voltage reference value and the first current sample value is higher than the current reference value. This activates the LED in the first optocoupler U2, causing its output to provide a low-impedance short-circuit signal to the main control circuit for short-circuit protection. This effectively distinguishes between short-circuit faults and temporary large currents caused by startup transients or line impedance. Although the startup current may exceed the safety threshold, the protection will not be triggered because the voltage has not yet dropped below the set value, thus avoiding false judgments. It also prevents startup voltage dips caused by line impedance or load characteristics from being mistaken for short circuits, thereby avoiding unnecessary power shutdowns or protection actions and improving power supply availability and system stability. By combining the dual conditions of voltage and current, accurate identification of real short-circuit faults is achieved while minimizing interference with transient processes during normal operation, significantly improving the intelligence and robustness of power supply protection.

[0050] Reference Figure 1 In some embodiments of this utility model, the protection device further includes: a power supply terminal, a selection circuit 600, a second optocoupler U3, a second current sampling circuit 500, and a second voltage sampling circuit 400.

[0051] The input terminal of the second voltage sampling circuit 400 is electrically connected to the power supply terminal, and the output terminal of the second voltage sampling circuit 400 is electrically connected to the constant voltage control port of the comparison control chip U1, that is, electrically connected to the fifteenth pin of the comparison control chip U1. The second voltage sampling circuit 400 can sample the power supply terminal to obtain the second voltage sampling value and output the second voltage sampling value to the comparison control chip U1.

[0052] The input terminal of the second current sampling circuit 500 is electrically connected to the power supply terminal, and the output terminal of the second current sampling circuit 500 is electrically connected to the constant current control port of the comparison control chip U1, that is, electrically connected to the eleventh pin of the comparison control chip U1. The second current sampling circuit 500 can sample the power supply terminal to obtain the second current sampling value and output the first current sampling value to the comparison control chip U1.

[0053] The comparator control chip U1 is electrically connected to one end of the selection circuit 600, specifically, pins 16 and 10 of the comparator control chip U1 are electrically connected to one end of the selection circuit 600. The other end of the selection circuit 600 is electrically connected to the cathode of the light-emitting diode of the second optocoupler U3.

[0054] When the second voltage sample value is higher than the voltage reference value, or when the second current sample value is higher than the current reference value, the sixteenth pin of the comparison control chip U1 outputs a low-level signal, or the tenth pin outputs a low-level signal. The low-level signal is the output control signal, which is output to the second optocoupler U3.

[0055] The anode of the LED in the second optocoupler U3 is electrically connected to the power supply terminal, and the output terminal of the second optocoupler U3 is electrically connected to the main control circuit. The second optocoupler U3 receives the control signal, and its LED conducts, outputting a control signal to the main control circuit in a low-impedance manner. This provides a control signal to the main circuit, achieving constant current and constant voltage regulation. This allows for accurate identification of actual short-circuit faults and enables constant current and constant voltage regulation.

[0056] The second optocoupler U3 is an LTV-357 optocoupler isolator. The second current sampling circuit 500 includes a second voltage divider resistor group RS2, and the resistors in the first voltage divider resistor group RS2 are connected in parallel. In addition, other discrete components may be included, which will not be described in detail in this embodiment.

[0057] Reference Figure 1 In some embodiments of this utility model, the selection circuit 600 includes: a second diode D2, a third diode D3, a second pull-down circuit, and a first pull-up circuit.

[0058] The anode of the second diode D2 is electrically connected to the cathode of the light-emitting diode of the second optocoupler U3, and the cathode of the second diode D2 is electrically connected to the third output terminal of the comparator control chip U1, that is, to the tenth pin of the comparator control chip U1.

[0059] The anode of the third diode D3 is electrically connected to the cathode of the light-emitting diode of the second optocoupler U3, and the cathode of the third diode D3 is electrically connected to the fourth output terminal of the comparator control chip U1, that is, to the sixteenth pin of the comparator control chip U1.

[0060] One end of the second pull-down circuit is electrically connected to the third output terminal of the comparator control chip U1, that is, to the tenth pin of the comparator control chip U1. One end of the second pull-down circuit is also electrically connected to the cathode of the second diode D2. The other end of the second pull-down circuit is electrically connected to the power supply terminal.

[0061] The second pull-down circuit includes: the fourth capacitor C4 and the twelfth resistor R12.

[0062] One end of the first pull-up circuit is connected to the fourth output terminal of the comparator control chip U1, that is, electrically connected to the sixteenth pin of the comparator control chip U1. The other end of the first pull-up circuit is also electrically connected to the cathode of the third diode D3. The other end of the first pull-up circuit is electrically connected to the output terminal of the second voltage sampling circuit 400, and also electrically connected to the constant voltage control port of the comparator control chip U1, that is, electrically connected to the fifteenth pin of the comparator control chip U1.

[0063] The first pull-up circuit includes: the fifth capacitor C5 and the thirteenth resistor R13.

[0064] Reference Figure 1 and Figure 3 In some embodiments of this utility model, the protection device further includes: a first pull-up resistor R7, a first diode D1, a first pull-down circuit, and a second pull-up circuit.

[0065] One end of the first pull-up resistor R7 is electrically connected to the anode of the light-emitting diode of the first optocoupler U2, and the other end of the first pull-up resistor R7 is electrically connected to the first output terminal of the comparator control chip U1, that is, electrically connected to the first pin of the comparator control chip U1.

[0066] The anode of the first diode D1 is electrically connected to the anode of the light-emitting diode of the first optocoupler U2, and the cathode of the first diode D1 is electrically connected to the second output terminal of the comparator control chip U1, that is, electrically connected to the seventh pin of the comparator control chip U1.

[0067] One end of the first pull-down circuit is electrically connected to the second output terminal of the comparator control chip U1, that is, electrically connected to the seventh pin of the comparator control chip U1. The other end of the first pull-down circuit is electrically connected to the power transmission terminal.

[0068] The first pull-down circuit includes: the third capacitor C3 and the eighth resistor R8.

[0069] One end of the second pull-up circuit is electrically connected to the first output terminal of the comparator control chip U1, that is, electrically connected to the first pin of the comparator control chip U1. The other end of the second pull-up circuit is electrically connected to the output terminal of the second voltage sampling circuit 400.

[0070] The second pull-up circuit includes a first capacitor C1 and a sixth resistor R6.

[0071] Reference Figures 1 to 3 In some embodiments of this utility model, the reference sampling circuit 100 includes: a second pull-up resistor R2, a first series resistor group, and a second series resistor group.

[0072] One end of the second pull-up resistor R2 is electrically connected to the power transmission terminal, and the other end of the second pull-up resistor R2 is electrically connected to the reference port of the comparator control chip U1, that is, electrically connected to the third and fourteenth pins of the comparator control chip U1.

[0073] One end of the first series resistor group is electrically connected to the other end of the second pull-up resistor R2, and the other end of the first series resistor group is electrically connected to the power transmission terminal. The first series resistor group is also electrically connected to the reference port of the comparator control chip U1, that is, to the fifth pin of the comparator control chip U1.

[0074] The first series resistor group includes a first adjustable resistor PR1. The control terminal of the first adjustable resistor is electrically connected to the reference port of the comparator control chip U1, that is, electrically connected to the fifth pin of the comparator control chip U1.

[0075] One end of the second series resistor group is electrically connected to the other end of the second pull-up resistor R2, and the other end of the second series resistor group is electrically connected to the power supply terminal. The second series resistor group is also electrically connected to the reference port of the comparator control chip U1, that is, to the twelfth pin of the comparator control chip U1.

[0076] The second series resistor group includes a second adjustable resistor PR2. The control terminal of the second adjustable resistor is electrically connected to the reference port of the comparator control chip U1, that is, electrically connected to the twelfth pin of the comparator control chip U1.

[0077] In some embodiments of another aspect of this utility model, reference is made to Figure 2A power supply system includes a constant current and constant voltage short circuit protection device in some embodiments of this utility model. The power supply system also includes a main control circuit 700, which is electrically connected to the output terminal of the first optocoupler U2 and the output terminal of the second optocoupler U3 in the constant current and constant voltage short circuit protection device.

[0078] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A constant voltage and constant current short-circuit protection device, characterized in that, include: The power transmission terminal, the reference sampling circuit, the first voltage sampling circuit, the first current sampling circuit, the first optocoupler, and the comparison control chip; The input terminals of the reference sampling circuit, the first voltage sampling circuit, and the first current sampling circuit are all connected to the power transmission terminal. The output terminal of the reference sampling circuit is connected to the reference port of the comparison control chip, and the reference sampling circuit is used to output voltage reference value and current reference value to the comparison control chip; The output terminal of the first voltage sampling circuit is connected to the voltage comparison port of the comparison control chip, and the first voltage sampling circuit is used to output a first voltage sample value to the comparison control chip. The output terminal of the first current sampling circuit is connected to the current comparison port of the comparison control chip, and the first current sampling circuit is used to output the first current sampling value to the comparison control chip. The comparison control chip is connected to the first optocoupler. The comparison control chip is used to output a short-circuit signal to the first optocoupler when it is determined that the first voltage sample value is lower than the voltage reference value and the first current sample value is higher than the current reference value. The comparison control chip is a TSM104 chip.

2. The constant voltage and constant current short-circuit protection device according to claim 1, characterized in that, Also includes: Power supply terminal, selection circuit, second optocoupler, second current sampling circuit and second voltage sampling circuit; The input terminals of the second voltage sampling circuit and the second current sampling circuit are connected to the power supply terminal. The output terminal of the second voltage sampling circuit is connected to the constant voltage control port of the comparison control chip, and the second voltage sampling circuit is used to output the second voltage sampling value to the comparison control chip; The output terminal of the second current sampling circuit is connected to the constant current control port of the comparison control chip, and the second current sampling circuit is used to output the second current sampling value to the comparison control chip. The second optocoupler is connected to the comparison control chip through the selection circuit. The comparison control chip is also used to output a control signal to the second optocoupler when it is determined that the second voltage sample value is higher than the voltage reference value or the second current sample value is higher than the current reference value.

3. The constant voltage and constant current short-circuit protection device according to claim 1, characterized in that, Also includes: The first pull-up resistor, the first diode, and the first pull-down circuit; The first pull-up resistor is connected to the anode of the light-emitting diode of the first optocoupler and the first output terminal of the comparator control chip, respectively. The anode of the first diode is connected to the cathode of the light-emitting diode of the first optocoupler, the cathode of the first diode is connected to the second output terminal of the comparator control chip, and the first pull-down circuit is connected to the second output terminal of the comparator control chip and the power transmission terminal, respectively.

4. The constant voltage and constant current short-circuit protection device according to claim 2, characterized in that, The selection circuit includes: a second diode, a third diode, and a second pull-down circuit; The anodes of the second diode and the third diode are both connected to the cathode of the light-emitting diode of the second optocoupler. The cathode of the second diode is connected to the third output terminal of the comparator control chip, and the cathode of the third diode is connected to the fourth output terminal of the comparator control chip. The second pull-down circuit is connected to the third output terminal and the power supply terminal of the comparator control chip, respectively.

5. The constant voltage and constant current short-circuit protection device according to claim 1, characterized in that, The reference sampling circuit includes: a second pull-up resistor, a first series resistor group, and a second series resistor group; The second pull-up resistor is connected to both the power transmission terminal and the reference port of the comparison control chip. The first series resistor group is connected to the second pull-up resistor and the reference port of the comparator control chip, respectively; The second series resistor group is connected to the second pull-up resistor and the reference port of the comparison control chip, respectively.

6. The constant voltage and constant current short-circuit protection device according to claim 4, characterized in that, The selection circuit includes: a first pull-up circuit; One end of the first pull-up circuit is connected to the fourth output terminal of the comparator control chip and the cathode of the third diode, respectively, and the other end of the first pull-up circuit is connected to the second voltage sampling circuit and the constant voltage control port of the comparator control chip, respectively.

7. The constant voltage and constant current short-circuit protection device according to claim 2, characterized in that, The anode of the light-emitting diode in the second optocoupler is connected to the power supply terminal.

8. The constant voltage and constant current short-circuit protection device according to claim 1, characterized in that, The first optocoupler is an LTV-357 optocoupler isolator.

9. The constant voltage and constant current short-circuit protection device according to claim 2, characterized in that, The second optocoupler is an LTV-357 optocoupler isolator.

10. A power supply system, characterized in that, Includes the constant voltage and constant current short circuit protection device as described in any one of claims 1 to 9.

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