JP2602413B2 - Switching power supply - Google Patents

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, and more particularly to a switching power supply having a plurality of output stop control signal inputs.

[0002]

2. Description of the Related Art Conventionally, a switching power supply of this type has, for example, two control signal inputs for stopping output, and each control signal is delayed by a different time from the input of each control signal. It is used for the purpose of stopping the output of the switching power supply.

FIG. 2 is a block diagram showing an example of a conventional switching power supply.

In FIG. 2, a stop signal generating section 1a in this conventional example comprises a resistor (R) 11a and a capacitor (C).
16 is a transistor (TR) 17 for the control signal 1
Determine the time before turning on. Resistance (R) 12a
The capacitor (C) 16 determines the time until the control signal 2 turns on the transistor (TR) 17. The resistor (R) 15 discharges the capacitor (C) 16 when the control signals 1 and 2 are not input. When the transistor (TR) 17 is turned on, the switching control unit 2
4, a control signal for stopping the switching of the switching power supply unit 2 is generated.

Next, the operation of this conventional example will be described.

When receiving the control signal 1, the transistor (TR) 17 is turned on with a delay time determined by the resistor (R) 11a and the capacitor (C) 16. The switching control unit 24 receives the signal to stop the switching of the switching circuit unit 22, and the output of the switching power supply unit 2 is stopped. Similarly, when the control signal 2 is received, the resistance (R) 1
The transistor (TR) 17 is turned on with a delay time determined by 2a and the capacitor (C) 16. The switching control unit 24 receives the signal and the switching circuit unit 22
Is stopped, and the output of the switching power supply unit 2 is stopped.

[0007]

This conventional switching power supply device has a time constant resistance (R) which determines a period until the output of the switching power supply device is stopped for each of the two control signals in the stop signal generator. R11a, R1
2a) and the capacitor (C16),
16) is common, for example, when one resistor (R11a) and C16 determine the delay time for one control signal, the other resistor (R11a) determines the other delay time.
The value of 12a) is limited in order to turn on the transistor (TR17), and there is a problem that the range of each delay time for two control signals is limited. Further, when the resistance values of the two resistors (R11a, R12a) change, the base current when the TR17 is turned on changes, and the current value of the stop signal to the switching control unit 24 for each control signal changes. There is a problem.

[0008]

A switching power supply according to the present invention converts an input AC voltage into a first direct current by a rectifying and smoothing circuit, and switches the first direct current by a switching section to form a high-frequency transformer. and a high frequency rectified and smoothed by the rectifier, the switching power supply unit for converting the second DC is smoothed after conversion into high-frequency voltage via a straight
The plurality of control include the same DC input impedance for each flow voltage level substantially identical plurality of control signals
A stop signal generation unit that sends out a plurality of delay signals having a delay time set independently in advance from the respective input points of the signals to the same interface of the switching unit and stops the output of the switching power supply unit, A first resistor having one end connected to an input terminal of a first control signal, a first capacitor having one end connected in series to the other end, and the other end connected to ground; Said
A second resistor having one end connected to an input terminal of a second control signal having a DC positive voltage level substantially the same as the first control signal ;
A second capacitor having one end connected in series to the other end and the other end connected to ground; and a second resistor having a cathode connected to a connection point between the first resistor and the first capacitor. A diode having an anode connected to a connection point of the diode and the second capacitor; a third resistor having one end connected to the cathode of the diode and the other end connected to ground; and a base connected to the cathode of the diode. possess a transistor whose collector is connected to the emitter is connected to the connected ground one control signal input terminal of the switching unit, each of said first and second control signals
The delay time from the input point of time to the turning on of the transistor
The first and second delay signals having different lengths are connected to the control signal input terminal.
Send to

[0009]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In FIG. 1, the present embodiment includes a switching power supply unit 2 and a stop signal generating unit 1 for sending out a control signal 1 or a signal for stopping the output of the switching power supply unit 2 by the control signal 2.

The switching power supply unit 2 includes an input smoothing circuit 21 for rectifying and smoothing the input AC voltage to a first direct current,
Switching circuit section 22 for switching first DC
And an output smoothing circuit 23 that rectifies and smoothes the high-frequency signal switched by the switching circuit unit 22 via a transformer and outputs a second DC having a predetermined voltage, and controls a switching operation of the switching circuit unit 22. A switching control unit 24 that stops a switching operation upon receiving a stop signal from the stop signal generating unit 1 and stops an output from the output smoothing circuit 23.

The stop signal generator 1 includes a resistor (R) 11 having one end connected to an input terminal 18 of the control signal 1 and a capacitor (C) having one end connected in series to the other end and the other end connected to ground. ) 16, R12 having one end connected to the input terminal 19 of the control signal 2, C13 having one end connected in series to the other end, and the other end connected to ground, and R11 and C
A diode (D) 14 having a cathode connected to a connection point with the anode 16 and an anode connected to a connection point between R12 and C13;
And a transistor R15 having one end connected to the cathode of D14 and the other end connected to ground, and a transistor (base) connected to D14, an emitter connected to ground, and a collector connected to the control signal input terminal of the switching control unit 24. TR) 17.

Next, the operation of this embodiment will be described.

When the control signal 1 is input, R11 and C16
TR17 turns on after a delay time determined by. The switching control unit 24 receives the ON signal, the switching of the switching circuit unit 22 is stopped, and the output of the switching power supply unit 2 is stopped.

Similarly, TR17 turns on after a delay time determined by R12 and C13 due to the input of control signal 2. The switching control unit 24 receives the ON signal, the switching of the switching circuit unit 22 is stopped, and the output of the switching power supply unit 2 is stopped. Here, in order to make the delay time for the control signal 2 longer than that for the control signal 1, if R11 = R12, only the capacity of C13 may be made larger than C16.

As a result, each of the control signals 1 and 2
If the DC positive voltage levels are the same, the switching control unit 24 does not change the base current when the TR 17 is turned on.
To the same interface, control signals by the control signals 1 and 2
The output of the switching power supply unit 2 can be stopped by transmitting a delay signal in which the delay time from the input time of each of the signals 1 and 2 to the turning on of the TR 17 is changed.

[0018]

As described above, according to the present invention, an input AC voltage is converted into a first direct current by a rectifying and smoothing circuit, and the first direct current is switched by a switching unit, and the high frequency is passed through a high frequency transformer. The DC power level is substantially the same as that of the switching power supply unit, which converts the voltage into a voltage, rectifies and smoothes it by high-frequency rectification and smoothing, converts it into a second DC, and outputs it.
The switching unit a plurality of delay signals having a delay time set in advance independently from each input point of the plurality of control signals comprise the same DC input in <br/> impedance for each one of the plurality of control signals By providing a stop signal generation unit for sending out to the same interface to stop the output of the switching power supply unit, the conventional constant value of the element for setting the delay time is not limited , and independently.
There is an effect that the range of each delay time difference due to the set delay time can be made wider than before.

In the case where a plurality of delay signals are transmitted as ON signals of the transistors, the collector current at the time of turning on the transistors can be made the same, so that the connection to the switching section is connected to the same interface for each of the plurality of delay signals. There is an effect that can be connected.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional example.

[Explanation of symbols]

 1, 1a Stop signal generation unit 2 Switching power supply unit 11, 11a, 12, 12a, 15 Resistance (R) 13, 16 Capacitor (C) 14 Diode (D) 17 Transistor (TR) 18, 19 Input terminal 21 Input smoothing circuit 22 switching circuit section 23 output smoothing circuit 24 switching control section

Claims (2)

(57) [Claims] 1. An input AC voltage is converted into a first direct current by a rectifying / smoothing circuit, and the first direct current is switched by a switching unit to be converted into a high-frequency voltage via a high-frequency transformer, followed by high-frequency rectification and smoothing. rectification, wherein the plurality includes a switching power supply unit for converting the second DC to smooth the same DC input impedance for each of the DC voltage level substantially identical plurality of control signals
And a stop signal generating unit for stopping the output of the switching power supply unit by transmitting a plurality of delay signals having a delay time set independently in advance from each input point of the control signal to the same interface of the switching unit. A switching power supply device comprising: 2. The stop signal generator includes a first resistor having one end connected to an input terminal of a first control signal, and a second resistor having one end connected in series to the other end and the other end connected to ground. 1 and a DC which is substantially the same as the first control signal.
A second resistor having one end connected to an input terminal of a second control signal having a positive voltage level, a second capacitor having one end connected in series to the other end, and the other end connected to ground; A diode having a cathode connected to a connection point between the first resistor and the first capacitor and an anode connected to a connection point between the second resistor and the second capacitor;
A third resistor having a cathode end connected to the other end of the diode is connected to ground, mosquitoes of the diode
Possess a transistor whose collector is connected to the base emitter connected to the connected ground one control signal input terminal of the switching unit to Sword, the first, second
2 from each input point of the control signal.
First and second delay signals having different delay times until the data is turned on
2. The switching power supply device according to claim 1 , wherein the control signal is transmitted to the control signal input terminal .