Automatic switch dummy load circuit

Abstract

The invention 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] The invention relates to the field of electronic circuits, in particular to an automatic switch dummy load circuit. Background Art

[0002] Many mainboards of existing electronic devices integrate multiple functional modules, and the power supply voltages required by each functional module may be different. Currently, each functional module is generally powered by a switching power supply with multiple outputs. However, due to the influence of voltage cross-regulation rate, transformer coupling, control IC soft start, etc., the DC voltage of a certain output of the switching power supply may float high, resulting in the risk of breakdown of the subsequent circuit connected to the output. For this reason, the existing switching power supply will add a dummy load circuit to the output circuit to achieve a suppression effect, but the dummy load circuit has a high temperature and consumes a lot of energy, which will cause the circuit efficiency of the switching power supply to become low.

[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 of the switching power supply from drifting high and reduce the power consumption of the switching power supply. Summary of the invention

[0004] The object of the present invention is to provide an automatic switching dummy load circuit, which can effectively suppress the output voltage of a switching power supply from drifting high and can reduce the power consumption of the switching power supply.

[0005] In order to achieve the above object, the solution of the present invention is: An automatic switch dummy load circuit 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 to the access end of the automatic switch dummy load circuit, and the access end of the automatic switch dummy load circuit is used to connect the output end of a switching power supply; the output end of the voltage sampling unit is connected to the control end of the electronic switch unit, the output end of the electronic switch unit is connected to the input end of the dummy load unit, and the output end of the dummy load unit is grounded.

[0006] The voltage sampling unit includes a resistor R1 and a resistor R2, a first end of the resistor R1 is connected to an input end of the voltage sampling unit, a second end of the resistor R1 and a first end of the resistor R2 are connected to an output end of the voltage sampling unit, and a second end of the resistor R2 is grounded.

[0007] The voltage sampling unit further includes a resistor R3, which is connected in parallel with the resistor R1.

[0008] The electronic switch unit includes a resistor R4, a resistor R5, a MOS tube Q1 and a reference voltage chip U1; the first end of the resistor R4 and the source of the MOS tube Q1 are connected to the input end of the electronic switch unit, the second end of the resistor R4 and the first end of the resistor R5 are connected to the gate of the MOS tube Q1, the drain of the MOS tube Q1 is connected to the output end of the electronic switch unit, the second end of the resistor R5 is connected to the CATHODE pin of the reference voltage chip U1, the REF pin of the reference voltage chip U1 is connected to the control end of the electronic switch unit, and the ANODE pin of the reference voltage chip U1 is grounded.

[0009] The model of the reference voltage chip U1 is AZ431AN-ATRE1.

[0010] The dummy load unit includes a resistor R6 and a resistor R7 connected in parallel.

[0011] After adopting the above scheme, the access end of the automatic switch dummy load circuit of the present invention is used to connect the output end of the switching power supply; when the output voltage of the output end connected to the switching power supply and the access end of the automatic switch dummy load circuit exceeds the set voltage threshold, the output voltage of the voltage sampling unit will turn on the electronic switch unit, thereby making the dummy load unit connected to the output end of the switching power supply and effectively suppressing the output voltage of the switching power supply from floating high; when the output voltage of the output end connected to the switching power supply and the access end of the automatic switch dummy load circuit does not exceed the set voltage threshold, the output voltage of the voltage sampling unit cannot turn on the electronic switch unit, thereby making the dummy load unit not connected to the output end of the switching power supply, so that the dummy load unit is not powered on, thereby effectively reducing the power consumption of the switching power supply and improving the circuit efficiency of the switching power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a circuit schematic diagram of the present invention. DETAILED DESCRIPTION

[0013] In order to further explain the technical solution of the present invention, the present invention is described in detail below through specific embodiments.

[0014] like Figure 1 As shown, the present invention discloses an automatic switching dummy load circuit, which includes a voltage sampling unit, an electronic switch unit and a dummy load unit; wherein the input end of the voltage sampling unit and the input end of the electronic switch unit are connected to the access end of the automatic switching dummy load circuit, and the access end of the automatic switching dummy load circuit is used to connect the output end of the switching power supply; the output end of the voltage sampling unit is connected to the control end of the electronic switch unit, the output end of the electronic switch unit is connected to the input end of the dummy load unit, and the output end of the dummy load unit is grounded.

[0015] The working principle of the automatic switch dummy load circuit of the present invention is: The access end of the automatic switch dummy load circuit of the present invention is connected to the output end of the switching power supply; when the output voltage of the output end connected to the switching power supply and the access end of the automatic switch dummy load circuit exceeds the set voltage threshold, the output voltage of the voltage sampling unit will turn on the electronic switch unit, thereby making the dummy load unit connected to the output end of the switching power supply and effectively suppressing the output voltage of the switching power supply from floating high; when the output voltage of the output end connected to the switching power supply and the access end of the automatic switch dummy load circuit does not exceed the set voltage threshold, the output voltage of the voltage sampling unit cannot turn on the electronic switch unit, thereby making the dummy load unit not connected to the output end of the switching power supply, making the dummy load unit not powered on, thereby effectively reducing the power consumption of the switching power supply and improving the circuit efficiency of the switching power supply.

[0016] In an embodiment of the present invention, the voltage sampling unit includes a resistor R1 and a resistor R2, and the resistor R1 and the resistor R2 form a voltage divider circuit; wherein the first end of the resistor R1 is connected to the input end of the voltage sampling unit, the second end of the resistor R1 and the first end of the resistor R2 are connected to the output end of the voltage sampling unit, and the second end of the resistor R2 is grounded. In addition, the voltage sampling unit may also include a resistor R3, which is arranged in parallel with the resistor R1, and the resistor R3 can play a shunt protection role. The present invention can set a set voltage threshold by setting the resistance values ​​of the resistors R1, R2 and R3.

[0017] In an embodiment of the present invention, the electronic switch unit includes a resistor R4, a resistor R5, a MOS tube Q1 and a reference voltage chip U1, and the model of the reference voltage chip U1 may be AZ431AN-ATRE1; wherein, the first end of the resistor R4 and the source of the MOS tube Q1 are connected to the input end of the electronic switch unit, the second end of the resistor R4 and the first end of the resistor R5 are connected to the gate of the MOS tube Q1, the drain of the MOS tube Q1 is connected to the output end of the electronic switch unit, the second end of the resistor R5 is connected to the CATHODE pin of the reference voltage chip U1, the REF pin of the reference voltage chip U1 is connected to the control end of the electronic switch unit, and the ANODE pin of the reference voltage chip U1 is grounded. When the output voltage of the output end connected to the access end of the switching power supply and the automatic switching dummy load circuit exceeds the set voltage threshold, the output voltage of the voltage sampling unit will turn on the reference voltage chip U1, and then turn on the MOS tube Q1 so that the dummy load unit is connected to the output end of the switching power supply; when the output voltage of the output end connected to the access end of the switching power supply and the automatic switching 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, and then turn off the MOS tube Q1 so that the dummy load unit is not connected to the output end of the switching power supply. The reference voltage chip U1 has the advantages of high reference voltage accuracy and good temperature characteristics, and can make the electronic switch unit more reliable and more sensitive.

[0018] In an embodiment of the present invention, the dummy load unit includes a resistor R6 and a resistor R7 connected in parallel.

[0019] The above embodiments and drawings do not limit the product form and style of the present invention. Any appropriate changes or modifications made by ordinary technicians in the relevant technical field should be deemed to be within the patent scope of the present invention.

Claims

1. An automatic switching dummy load circuit, characterized in that: It includes 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 to the access end of the automatic switch dummy load circuit, and the access end of the automatic switch dummy load circuit is used to connect the output end of the switching power supply; the output end of the voltage sampling unit is connected to the control end of the electronic switch unit, the output end of the electronic switch unit is connected to the input end of the dummy load unit, and the output end of the dummy load unit is grounded.

2. The automatic switch dummy load circuit according to claim 1, characterized in that: The voltage sampling unit includes a resistor R1 and a resistor R2, a first end of the resistor R1 is connected to an input end of the voltage sampling unit, a second end of the resistor R1 and a first end of the resistor R2 are connected to an output end of the voltage sampling unit, and a second end of the resistor R2 is grounded.

3. The automatic switch dummy load circuit according to claim 2, characterized in that: The voltage sampling unit further includes a resistor R3, which is connected in parallel with the resistor R1.

4. The automatic switch dummy load circuit according to claim 1, characterized in that: The electronic switch unit includes a resistor R4, a resistor R5, a MOS tube Q1 and a reference voltage chip U1; the first end of the resistor R4 and the source of the MOS tube Q1 are connected to the input end of the electronic switch unit, the second end of the resistor R4 and the first end of the resistor R5 are connected to the gate of the MOS tube Q1, the drain of the MOS tube Q1 is connected to the output end of the electronic switch unit, the second end of the resistor R5 is connected to the CATHODE pin of the reference voltage chip U1, the REF pin of the reference voltage chip U1 is connected to the control end of the electronic switch unit, and the ANODE pin of the reference voltage chip U1 is grounded.

5. The automatic switch dummy load circuit according to claim 4, characterized in that: The model of the reference voltage chip U1 is AZ431AN-ATRE1.

6. The automatic switch dummy load circuit according to claim 1, characterized in that: The dummy load unit includes a resistor R6 and a resistor R7 connected in parallel.

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