JPH0556634A - Switching power circuit - Google Patents

Abstract

PURPOSE:To obtain the original output voltage and the voltage twice as large as the output voltage simply and simultaneously by adding a charge pump circuit by utilizing the operation of the transistor-switch of a switching power supply. CONSTITUTION:A switching power circuit is composed of a positive input power terminal 1 and a negative input power terminal 2, a coil 3 and a control circuit 4, a first diode 5, a second diode 6, a third diode 7, a first capacitor 8, a second capacitor 9, a third capacitor 10, an N-P-N transistor 11, a first positive output terminal 12, a second positive output terminal 13 and an output ground terminal 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching power supply circuit, and more particularly to a circuit for obtaining a boosted positive voltage output and at the same time obtaining a positive voltage output having a voltage value twice that of the boosted positive voltage output.

[0002]

2. Description of the Related Art Conventional switching power supply circuits of this type are
Two boosting power supply circuits were used as in the circuit of FIG.
Here, 21 is a positive input power supply terminal, 22 is a negative input power supply terminal,
23 is a first coil, 24 is a second coil, 25 is a first control circuit, 26 is a second control circuit, 27 is a first diode, 2
8 is a second diode, 29 is a first NPN transistor, 30 is a second NPN transistor, 31 is a first capacitor, 32 is a second capacitor, 33 is a first positive output terminal, and 34 is a second positive output. The terminal 35 is an output ground terminal.

[0003]

The conventional switching power supply circuit described above uses two switching power supply circuits, and therefore has the drawback that the circuit is complicated and expensive.

An object of the present invention is to provide a switching power supply circuit which can easily obtain an original output voltage and a voltage twice as high as the original output voltage by adding a charge pump circuit by utilizing the operation of a transistor switch of the switching power supply. ..

[0005]

A switching power supply circuit of the present invention includes a positive input power supply terminal, a negative input power supply terminal, a first positive output terminal, a second positive output terminal, an output ground terminal, a control circuit, and a coil. An NPN transistor, a first diode, a second diode, a third diode, a first capacitor, a second capacitor and a third capacitor,
The positive input power supply terminal, one end of the coil and the positive power supply terminal of the control circuit are connected, and the other end of the coil is connected to the collector of the NPN transistor, the anode of the first diode and the one end of the first capacitor, The cathode of the first diode, one end of the second capacitor, the first positive output terminal, the detection terminal of the control circuit, and the anode of the second diode are connected, and the control terminal of the control circuit and the NPN transistor are connected. The base is connected, the other end of the first capacitor is connected to the cathode of the second diode and the anode of the third diode, and the cathode of the third diode, one end of the third capacitor and the second positive electrode are connected. The output terminal is connected to the other end of the third capacitor, the negative power supply terminal of the control circuit, the emitter of the NPN transistor, and the second terminal.
The other end of the capacitor is connected to the negative power supply input terminal and the output ground terminal.

[0006]

The present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention. In the figure, 1 is a positive input power supply terminal, 2 is a negative input power supply terminal, 3 is a coil, 4 is a control circuit, 5 is a first diode, 6 is a second diode, 7 is a third diode, and 8
Is a first capacitor, 9 is a second capacitor, 10 is a third capacitor, 11 is an NPN transistor, 12 is a first positive output terminal, 13 is a second positive output terminal, and 14 is an output ground terminal. ..

Energy is stored in the coil 3 when the NPN transistor 11 is turned on. NPN transistor 11
When is off, the energy of the coil 3 is charged in the second capacitor 9 through the first diode 5. When the voltage of the second capacitor 9 rises sufficiently, the control circuit 4
The charging of the capacitor 9 is stopped. As a result, a boosted voltage is obtained at the first output terminal.

When the NPN transistor 11 is turned on, the first capacitor 8 changes from the second capacitor 9 to the second capacitor 9.
Collector of diode 6 and NPN transistor 11
Charged through the emitter.

If the voltage loss between the collector and the emitter of the second diode 6 and the NPN transistor 11 is negligible, this charges the first capacitor 8 to a voltage equal to that of the second capacitor 9.

Next, when the NPN transistor 11 is turned off, the voltage of the collector of the NPN transistor 11 becomes the first voltage.
Rises to a voltage equal to that of the positive output terminal 12. Since the first capacitor 8 is charged to the same voltage as the second capacitor 9 as described above, the third capacitor 10 is charged through the third diode 7, and therefore the double of the first positive output terminal 12 is generated. Becomes the voltage of. Therefore, twice the voltage of the first positive output terminal 12 can be taken out from the second positive output terminal 13.

[0012]

As described above, according to the present invention, the negative output voltage twice the positive output voltage can be obtained from the conventional step-up switching power supply by using the two capacitors and the two diodes.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a circuit diagram of an example of a conventional circuit.

[Explanation of symbols] 1 positive input power supply terminal 2 negative input power supply terminal 3 coil 4 control circuit 5 first diode 6 second diode 7 third diode 8 first capacitor 9 second capacitor 10 third capacitor 11 NPN transistor 12 1st positive output terminal 13 2nd positive output terminal 14 Output ground terminal

Claims (1)

[Claims] 1. A positive input power supply terminal, a negative input power supply terminal, and a first
Positive output terminal, second positive output terminal, output ground terminal, control circuit, coil, NPN transistor, first diode, second diode, third diode, first capacitor, second capacitor, and And a capacitor connected to the positive input power supply terminal, one end of the coil and the positive power supply terminal of the control circuit, the other end of the coil, the collector of the NPN transistor, the anode of the first diode, and the first diode. One end of the capacitor is connected, the cathode of the first diode, one end of the second capacitor, the first positive output terminal, the detection terminal of the control circuit, and the anode of the second diode are connected, The control terminal is connected to the base of the NPN transistor, and the other end of the first capacitor, the cathode of the second diode and the anode of the third diode are connected. And the cathode of the third diode, one end of the third capacitor, and the second positive output terminal are connected, the other end of the third capacitor, the negative power supply terminal of the control circuit, and the emitter of the NPN transistor. And the second
The switching power supply circuit is characterized in that the other end of the capacitor is connected to the negative power supply input terminal and the output ground terminal.