Automatic switch dummy load circuit

Abstract

The utility model discloses an automatic switch dummy load circuit which comprises a voltage sampling unit, an electronic switch unit and a dummy load unit. The input end of the voltage sampling unit and the input end of the electronic switch unit are connected with the access end of the automatic switch dummy load circuit, and the access end of the automatic switch dummy load circuit is used for being connected with the output end of a switch power supply; the output end of the voltage sampling unit is connected with the control end of the electronic switch unit, the output end of the electronic switch unit is connected with the input end of the dummy load unit, and the output end of the dummy load unit is grounded. The high output voltage drift of the switching power supply can be effectively inhibited, and the power consumption of the switching power supply can be reduced.

Description

Technical Field

[0001] This utility model relates to the field of electronic circuits, and in particular to an automatic switching dummy load circuit. Background Technology

[0002] Many existing electronic devices have motherboards that integrate multiple functional modules, each requiring different power supply voltages. Currently, multi-output switching power supplies are generally used to power each module separately. However, due to factors such as voltage cross-regulation, transformer coupling, and soft-start of the control IC, the DC voltage of one output of the switching power supply may drift excessively, posing a risk of breakdown to downstream circuits connected to that output. To address this, existing switching power supplies add dummy load circuits to the output circuit to suppress this effect. However, dummy load circuits have high temperatures and high energy consumption, which reduces the efficiency of the switching power supply.

[0003] In view of the above problems, it is necessary to study an automatic switching dummy load circuit, which can effectively suppress the output voltage drift of the switching power supply and reduce the power consumption of the switching power supply. Utility Model Content

[0004] The purpose of this invention is to provide an automatic switching dummy load circuit, which can effectively suppress the output voltage drift of the switching power supply and reduce the power consumption of the switching power supply.

[0005] To achieve the above objectives, the solution of this utility model is:

[0006] An automatic switching dummy load circuit includes a voltage sampling unit, an electronic switching unit, and a dummy load unit. The input terminals of the voltage sampling unit and the electronic switching unit are connected to the access terminals of the automatic switching dummy load circuit, which are used to connect to the output terminal of a switching power supply. The output terminal of the voltage sampling unit is connected to the control terminal of the electronic switching unit, the output terminal of the electronic switching unit is connected to the input terminal of the dummy load unit, and the output terminal of the dummy load unit is grounded.

[0007] The voltage sampling unit includes resistors R1 and R2. The first end of resistor R1 is connected to the input terminal of the voltage sampling unit, the second end of resistor R1 and the first end of resistor R2 are connected to the output terminal of the voltage sampling unit, and the second end of resistor R2 is grounded.

[0008] The voltage sampling unit also includes a resistor R3, which is connected in parallel with the resistor R1.

[0009] The electronic switching unit includes resistor R4, resistor R5, MOSFET Q1, and reference voltage chip U1. The first end of resistor R4 and the source of MOSFET Q1 are connected to the input terminal of the electronic switching unit. The second end of resistor R4 and the first end of resistor R5 are connected to the gate of MOSFET Q1. The drain of MOSFET Q1 is connected to the output terminal of the electronic switching unit. The second end of resistor R5 is connected to the CATHODE pin of reference voltage chip U1. The REF pin of reference voltage chip U1 is connected to the control terminal of the electronic switching unit. The ANODE pin of reference voltage chip U1 is grounded.

[0010] The reference voltage chip U1 is model AZ431AN-ATRE1.

[0011] The dummy load unit includes resistors R6 and R7 connected in parallel.

[0012] With the above solution, the input terminal of the automatic switching dummy load circuit of this utility model is used to connect to the output terminal of the switching power supply. When the output voltage of the output terminal connected to the input terminal of the automatic switching dummy load circuit exceeds the set voltage threshold, the output voltage of the voltage sampling unit will cause the electronic switching unit to conduct, thereby allowing the dummy load unit to be connected to the output terminal of the switching power supply and effectively suppressing the output voltage drift of the switching power supply. When the output voltage of the output terminal connected to the input terminal of the automatic switching dummy load circuit does not exceed the set voltage threshold, the output voltage of the voltage sampling unit cannot cause the electronic switching unit to conduct, thereby preventing the dummy load unit from being connected to the output terminal of the switching power supply and preventing the dummy load unit from being powered on, thus effectively reducing the power consumption of the switching power supply and improving the circuit efficiency of the switching power supply. Attached Figure Description

[0013] Figure 1 This is the circuit schematic diagram of this utility model. Detailed Implementation

[0014] To further explain the technical solution of this utility model, the following detailed description is provided through specific embodiments.

[0015] like Figure 1 As shown, this utility model discloses an automatic switching dummy load circuit, which includes a voltage sampling unit, an electronic switching unit, and a dummy load unit; wherein, the input terminal of the voltage sampling unit and the input terminal of the electronic switching unit are connected to the access terminal of the automatic switching dummy load circuit, and the access terminal of the automatic switching dummy load circuit is used to connect to the output terminal of the switching power supply; the output terminal of the voltage sampling unit is connected to the control terminal of the electronic switching unit, the output terminal of the electronic switching unit is connected to the input terminal of the dummy load unit, and the output terminal of the dummy load unit is grounded.

[0016] The working principle of the automatic switching dummy load circuit of this utility model is as follows:

[0017] The automatic switching dummy load circuit of this invention has its input terminal connected to the output terminal of a switching power supply. When the output voltage of the switching power supply connected to the input terminal of the automatic switching dummy load circuit exceeds a set voltage threshold, the output voltage of the voltage sampling unit will cause the electronic switching unit to conduct, thereby allowing the dummy load unit to be connected to the output terminal of the switching power supply and effectively suppressing the output voltage drift of the switching power supply. When the output voltage of the switching power supply connected to the input terminal of the automatic switching dummy load circuit does not exceed the set voltage threshold, the output voltage of the voltage sampling unit cannot cause the electronic switching unit to conduct, thereby preventing the dummy load unit from being connected to the output terminal of the switching power supply and preventing the dummy load unit from being powered on, thus effectively reducing the power consumption of the switching power supply and improving the circuit efficiency of the switching power supply.

[0018] In an embodiment of this invention, the voltage sampling unit includes resistors R1 and R2, which form a voltage divider circuit. The first end of resistor R1 is connected to the input terminal of the voltage sampling unit, and the second ends of resistor R1 and the first end of resistor R2 are connected to the output terminal of the voltage sampling unit. The second end of resistor R2 is grounded. Furthermore, the voltage sampling unit may also include resistor R3, which is connected in parallel with resistor R1 and serves as a shunt protection. This invention allows setting a voltage threshold by adjusting the resistance values ​​of resistors R1, R2, and R3.

[0019] In an embodiment of this utility model, the electronic switching unit includes resistor R4, resistor R5, MOSFET Q1, and reference voltage chip U1, wherein the reference voltage chip U1 can be of model AZ431AN-ATRE1; wherein, the first end of resistor R4 and the source of MOSFET Q1 are connected to the input end of the electronic switching unit, the second end of resistor R4 and the first end of resistor R5 are connected to the gate of MOSFET Q1, the drain of MOSFET Q1 is connected to the output end of the electronic switching unit, the second end of resistor R5 is connected to the CATHODE pin of reference voltage chip U1, the REF pin of reference voltage chip U1 is connected to the control end of the electronic switching unit, and the ANODE pin of reference voltage chip U1 is grounded. When the output voltage at the output terminal connected to the automatic dummy load circuit exceeds the set voltage threshold, the output voltage of the voltage sampling unit will turn on the reference voltage chip U1, which in turn turns on the MOSFET Q1, allowing the dummy load unit to be connected to the output terminal of the switching power supply. When the output voltage at the output terminal connected to the automatic dummy load circuit does not exceed the set voltage threshold, the output voltage of the voltage sampling unit cannot turn on the reference voltage chip U1, which in turn turns off the MOSFET Q1, preventing the dummy load unit from being connected to the output terminal of the switching power supply. This reference voltage chip U1 has the advantages of high reference voltage accuracy and good temperature characteristics, making the electronic switching unit more reliable and more responsive.

[0020] In an embodiment of this utility model, the dummy load unit includes resistors R6 and R7 connected in parallel.

[0021] The above embodiments and figures are not intended to limit the product form and style of this utility model. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of this utility model.

Claims

1. An automatic switching dummy load circuit, characterized in that: It includes a voltage sampling unit, an electronic switching unit, and a dummy load unit; The input terminals of the voltage sampling unit and the electronic switch unit are connected to the access terminals of the automatic switch dummy load circuit, which is used to connect to the output terminal of the switching power supply; the output terminal of the voltage sampling unit is connected to the control terminal of the electronic switch unit, the output terminal of the electronic switch unit is connected to the input terminal of the dummy load unit, and the output terminal of the dummy load unit is grounded. The electronic switching unit includes resistor R4, resistor R5, MOSFET Q1, and reference voltage chip U1. The first end of resistor R4 and the source of MOSFET Q1 are connected to the input terminal of the electronic switching unit. The second end of resistor R4 and the first end of resistor R5 are connected to the gate of MOSFET Q1. The drain of MOSFET Q1 is connected to the output terminal of the electronic switching unit. The second end of resistor R5 is connected to the CATHODE pin of reference voltage chip U1. The REF pin of reference voltage chip U1 is connected to the control terminal of the electronic switching unit. The ANODE pin of reference voltage chip U1 is grounded.

2. The automatic switching dummy load circuit as described in claim 1, characterized in that: The voltage sampling unit includes resistors R1 and R2. The first end of resistor R1 is connected to the input terminal of the voltage sampling unit, the second end of resistor R1 and the first end of resistor R2 are connected to the output terminal of the voltage sampling unit, and the second end of resistor R2 is grounded.

3. The automatic switching dummy load circuit as described in claim 2, characterized in that: The voltage sampling unit also includes a resistor R3, which is connected in parallel with the resistor R1.

4. The automatic switching dummy load circuit as described in claim 1, characterized in that: The reference voltage chip U1 is model AZ431AN-ATRE1.

5. The automatic switching dummy load circuit as described in claim 1, characterized in that: The dummy load unit includes resistors R6 and R7 connected in parallel.

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