Output voltage stabilizing circuit of multi-output switching power supply

Abstract

The utility model discloses an output voltage stabilizing circuit of a multi-output switching power supply. The output voltage stabilizing circuit comprises a voltage input end Vint, a voltage output end Vout, a voltage regulating circuit and a current regulating circuit, the input end and the output end of the current regulating circuit are respectively connected with a voltage input end Vint and a voltage output end Vout; the input end and the output end of the current adjusting circuit are connected with the voltage output end Vout and the control end of the voltage adjusting circuit respectively, the current adjusting circuit correspondingly adjusts the current of the control end of the voltage adjusting circuit according to the voltage of the voltage output end Vout, and then the voltage of the voltage output end Vout is adjusted. The multi-output switching power supply can ensure that the output voltage of the multi-output switching power supply is stable.

Description

Technical Field

[0001] The utility model relates to the field of switching power supplies, in particular to an output voltage stabilizing circuit of a multi-output switching power supply. Background Art

[0002] A multi-output switching power supply is a switching power supply with at least two outputs. When one output of the multi-output switching power supply is loaded and the other output is unloaded, the output voltage of the unloaded output will be very high, and the output voltage of the loaded output will also become very low, which will cause the load circuit at the back end to work abnormally or even be damaged. The current solution to this problem is generally to connect a dummy load in series between each output of the multi-output switching power supply and the ground to stabilize the output voltage, but the improvement effect of the dummy load is not obvious and it also increases power consumption. When the output current of the multi-output switching power supply changes, the output voltage of the multi-output switching power supply will still change.

[0003] In view of the existence of the above problems, it is necessary to study an output voltage stabilizing circuit of a multi-output switching power supply, which can ensure the stability of the output voltage of the multi-output switching power supply. Utility Model Content

[0004] The utility model aims to provide an output voltage stabilizing circuit of a multi-output switching power supply, which can ensure the output voltage stability of the multi-output switching power supply.

[0005] In order to achieve the above purpose, the solution of the utility model is:

[0006] An output voltage stabilizing circuit of a multi-output switching power supply comprises a voltage input terminal Vint, a voltage output terminal Vout, a voltage regulating circuit and a current regulating circuit; the voltage regulating circuit comprises a MOS tube M1, a triode Q1 and a resistor R1, the source of the MOS tube M1 and the emitter of the triode Q1 are connected to the input terminal of the voltage regulating circuit, the drain of the MOS tube M1 is connected to the voltage output terminal Vout, the gate of the MOS tube M1 is connected to the first end of the resistor R1, the second end of the resistor R1 is connected to the collector of the triode Q1, and the output end of the triode Q1 is connected to the control end of the voltage regulating circuit; the input end and the output end of the current regulating circuit are respectively connected to the voltage input terminal Vint and the voltage output terminal Vout; the input end and the output end of the current regulating circuit are respectively connected to the voltage output terminal Vout and the control end of the voltage regulating circuit, and the current regulating circuit correspondingly regulates the current of the control end of the voltage regulating circuit according to the voltage of the voltage output terminal Vout.

[0007] The current regulating circuit includes a resistor R2, a resistor R3, a capacitor C1, a three-terminal adjustable shunt reference source U1 and a voltage acquisition unit. The model of the adjustable shunt reference source U1 is TL341. The input end of the voltage acquisition unit is connected to the input end of the current regulating circuit, the output end of the voltage acquisition unit is connected to the reference end of the three-terminal adjustable shunt reference source U1 and the first end of the capacitor C1, the cathode of the three-terminal adjustable shunt reference source U1 and the second end of the capacitor C1 are connected to the first end of the resistor R3, the anode of the three-terminal adjustable shunt reference source U1 is grounded, the first end of the resistor R2 and the second end of the resistor R3 are connected to the output end of the current regulating circuit, and the second end of the resistor R2 is connected to the voltage input terminal Vint.

[0008] The voltage acquisition unit includes a resistor R4 and a resistor R5, a first end of the resistor R4 is connected to an input end of the voltage acquisition unit, a second end of the resistor R4 and a first end of the resistor R5 are connected to an output end of the voltage acquisition unit, and a second end of the resistor R5 is grounded.

[0009] The voltage acquisition unit further includes a resistor R6 connected in parallel with the resistor R4.

[0010] The voltage acquisition unit further includes a resistor R7 connected in parallel with the resistor R5.

[0011] After adopting the above scheme, when the output voltage stabilizing circuit of a multi-output switching power supply of the utility model is used, each path of the multi-output switching power supply is output through the output voltage stabilizing circuit of a multi-output switching power supply of the utility model, that is, the voltage of the voltage output terminal Vout is the output voltage of the multi-output switching power supply.

[0012] In the utility model, when the voltage of the voltage output terminal Vout (i.e., the output voltage of the multi-output switching power supply) exceeds a set threshold value, the current regulating circuit increases the control terminal current of the voltage regulating circuit (i.e., increases the base current of the transistor Q1), thereby increasing the emitter current of the transistor Q1 and increasing the gate voltage of the MOS tube M1, thereby reducing the gate-source voltage difference of the MOS tube M1 and reducing the conduction degree of the MOS tube M1, so as to reduce the output voltage of the voltage output terminal Vout (i.e., reduce the output voltage of the multi-output switching power supply); in the utility model, when the voltage of the voltage output terminal Vout (i.e., the output voltage of the multi-output switching power supply) is less than a set threshold value, the current regulating circuit reduces the control terminal current of the voltage regulating circuit (i.e., reduces the base current of the transistor Q1), thereby reducing the emitter current of the transistor Q1 and reducing the gate voltage of the MOS tube M1, thereby increasing the gate-source voltage difference of the MOS tube M1 and increasing the conduction degree of the MOS tube M1, so as to increase the output voltage of the voltage output terminal Vout (i.e., increase the output voltage of the multi-output switching power supply).

[0013] It can be seen from the above that the output voltage stabilizing circuit of a multi-output switching power supply of the utility model can automatically adjust the output voltage of the multi-output switching power supply to ensure the stability of the output voltage of the multi-output switching power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a circuit schematic diagram of the utility model. DETAILED DESCRIPTION

[0015] In order to further explain the technical solution of the present utility model, the present utility model is described in detail below through specific embodiments.

[0016] like Figure 1 As shown, the utility model discloses an output voltage stabilizing circuit of a multi-output switching power supply, which includes a voltage input terminal Vint, a voltage output terminal Vout, a voltage regulating circuit and a current regulating circuit; the input terminal and the output terminal of the current regulating circuit are respectively connected to the voltage input terminal Vint and the voltage output terminal Vout; the input terminal and the output terminal of the current regulating circuit are respectively connected to the voltage output terminal Vout and the control terminal of the voltage regulating circuit, and the current regulating circuit adjusts the current of the control terminal of the voltage regulating circuit according to the voltage of the voltage output terminal Vout, thereby adjusting the voltage of the voltage output terminal Vout; when the output voltage stabilizing circuit of the multi-output switching power supply of the utility model is used, each path of the multi-output switching power supply is output through the output voltage stabilizing circuit of the multi-output switching power supply of the utility model, that is, the voltage of the voltage output terminal Vout is the output voltage of the multi-output switching power supply.

[0017] In an embodiment of the utility model, the voltage regulating circuit includes a MOS tube M1, a transistor Q1 and a resistor R1, the source of the MOS tube M1 and the emitter of the transistor Q1 are connected to the input end of the voltage regulating circuit, the drain of the MOS tube M1 is connected to the voltage output end Vout, the gate of the MOS tube M1 is connected to the first end of the resistor R1, the second end of the resistor R1 is connected to the collector of the transistor Q1, and the output end of the transistor Q1 is connected to the control end of the voltage regulating circuit. In the present invention, when the voltage at the voltage output terminal Vout (i.e., the output voltage of the multi-output switching power supply) exceeds a set threshold, the current regulating circuit increases the control terminal current of the voltage regulating circuit (i.e., increases the base current of the transistor Q1), thereby increasing the emitter current of the transistor Q1 and increasing the gate voltage of the MOS tube M1, thereby reducing the gate-source voltage difference of the MOS tube M1 and reducing the conduction degree of the MOS tube M1, so as to reduce the output voltage of the voltage output terminal Vout (i.e., reduce the output voltage of the multi-output switching power supply); when the voltage at the voltage output terminal Vout (i.e., the output voltage of the multi-output switching power supply) is less than a set threshold, the current regulating circuit reduces the control terminal current of the voltage regulating circuit (i.e., reduces the base current of the transistor Q1), thereby reducing the emitter current of the transistor Q1 and reducing the gate voltage of the MOS tube M1, thereby increasing the gate-source voltage difference of the MOS tube M1 and increasing the conduction degree of the MOS tube M1, so as to increase the output voltage of the voltage output terminal Vout (i.e., increase the output voltage of the multi-output switching power supply). It can be seen from the foregoing that the output voltage stabilizing circuit of a multi-output switching power supply of the utility model can automatically adjust the output voltage of the multi-output switching power supply to ensure the stability of the output voltage of the multi-output switching power supply.

[0018] In an embodiment of the utility model, the current regulating circuit includes a resistor R2, a resistor R3, a capacitor C1, a three-terminal adjustable shunt reference source U1 and a voltage acquisition unit, the model of the adjustable shunt reference source U1 is TL341, the input end of the voltage acquisition unit is connected to the input end of the current regulating circuit, the voltage acquisition unit is used to collect the voltage of the voltage output end Vout, the output end of the voltage acquisition unit is connected to the reference end of the three-terminal adjustable shunt reference source U1 and the first end of the capacitor C1, the cathode of the three-terminal adjustable shunt reference source U1 and the second end of the capacitor C1 are connected to the first end of the resistor R3, the anode of the three-terminal adjustable shunt reference source U1 is grounded, the first end of the resistor R2 and the second end of the resistor R3 are connected to the output end of the current regulating circuit, and the second end of the resistor R2 is connected to the voltage input end Vint. In the present invention, when the voltage of the voltage output terminal Vout (i.e., the output voltage of the multi-output switching power supply) exceeds a set threshold value (i.e., the reference voltage of the three-terminal adjustable shunt reference source U1), the cathode of the three-terminal adjustable shunt reference source U1 will output a low voltage signal, so that the control terminal current of the voltage regulating circuit will be increased (i.e., the base current of the transistor Q1 will be increased) with the cooperation of the resistor R2 and the resistor R3; in the present invention, when the voltage of the voltage output terminal Vout (i.e., the output voltage of the multi-output switching power supply) is less than the set threshold value (i.e., the reference voltage of the three-terminal adjustable shunt reference source U1), the cathode of the three-terminal adjustable shunt reference source U1 will output a high voltage signal, so that the control terminal current of the voltage regulating circuit will be reduced (i.e., the base current of the transistor Q1 will be increased) with the cooperation of the resistor R2 and the resistor R3.

[0019] In an embodiment of the utility model, the voltage acquisition unit includes a resistor R4 and a resistor R5, the first end of the resistor R4 is connected to the input end of the voltage acquisition unit, the second end of the resistor R4 and the first end of the resistor R5 are connected to the output end of the voltage acquisition unit, and the second end of the resistor R5 is grounded; such a configuration makes the voltage acquisition unit actually a voltage divider circuit, which can avoid damaging the three-terminal adjustable shunt reference source U1. Further, the voltage acquisition unit may also include a resistor R6 connected in parallel with the resistor R4, and the resistor R6 can play a shunt role to further protect the three-terminal adjustable shunt reference source U1. Similarly, the voltage acquisition unit may also include a resistor R7 connected in parallel with the resistor R5, and the resistor R7 can play a shunt role to further protect the three-terminal adjustable shunt reference source U1.

[0020] The above embodiments and drawings do not limit the product form and style of the present utility model. 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 utility model.

Claims

1. An output voltage stabilizing circuit for a multi-output switching power supply, characterized in that: It includes a voltage input terminal Vint, a voltage output terminal Vout, a voltage regulating circuit and a current regulating circuit; The voltage regulating circuit includes a MOS tube M1, a triode Q1 and a resistor R1, the source of the MOS tube M1 and the emitter of the triode Q1 are connected to the input end of the voltage regulating circuit, the drain of the MOS tube M1 is connected to the voltage output end Vout, the gate of the MOS tube M1 is connected to the first end of the resistor R1, the second end of the resistor R1 is connected to the collector of the triode Q1, and the output end of the triode Q1 is connected to the control end of the voltage regulating circuit; the input end and the output end of the current regulating circuit are respectively connected to the voltage input end Vint and the voltage output end Vout; The input end and the output end of the current regulating circuit are respectively connected to the voltage output end Vout and the control end of the voltage regulating circuit. The current regulating circuit adjusts the current of the control end of the voltage regulating circuit according to the voltage of the voltage output end Vout.

2. The output voltage stabilizing circuit of a multi-output switching power supply according to claim 1, characterized in that: The current regulating circuit includes a resistor R2, a resistor R3, a capacitor C1, a three-terminal adjustable shunt reference source U1 and a voltage acquisition unit. The model of the adjustable shunt reference source U1 is TL341. The input end of the voltage acquisition unit is connected to the input end of the current regulation circuit, the output end of the voltage acquisition unit is connected to the reference end of the three-terminal adjustable shunt reference source U1 and the first end of the capacitor C1, the cathode of the three-terminal adjustable shunt reference source U1 and the second end of the capacitor C1 are connected to the first end of the resistor R3, the anode of the three-terminal adjustable shunt reference source U1 is grounded, the first end of the resistor R2 and the second end of the resistor R3 are connected to the output end of the current regulation circuit, and the second end of the resistor R2 is connected to the voltage input terminal Vint.

3. The output voltage stabilizing circuit of a multi-output switching power supply according to claim 2, characterized in that: The voltage acquisition unit includes a resistor R4 and a resistor R5, a first end of the resistor R4 is connected to an input end of the voltage acquisition unit, a second end of the resistor R4 and a first end of the resistor R5 are connected to an output end of the voltage acquisition unit, and a second end of the resistor R5 is grounded.

4. The output voltage stabilizing circuit of a multi-output switching power supply according to claim 3, characterized in that: The voltage acquisition unit further includes a resistor R6 connected in parallel with the resistor R4.

5. The output voltage stabilizing circuit of a multi-output switching power supply according to claim 3, characterized in that: The voltage acquisition unit further includes a resistor R7 connected in parallel with the resistor R5.

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