JPH11252910A - Power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power unit in which power saving is performed and overcurrent protection operate normally. SOLUTION: At power saving operation, a power saving signal 8 from a host system is received, an output voltage V1 is lowered by a secondary circuit 7, and power is supplied to a primary circuit 3 from a second tertiary winding 532, thereby maintaining power saving operation. At the overcurrent protecting operation of the output voltage V1, it is decreased, voltage increase of a receiving photocoupler PCR is detected, a second transistor Q2 is turned on by a resistor R1 and by a detection diode ZD1, and power supply from a first tertiary winding 531 to the primary circuit 3 is cut off, thereby preventing the elongation of a drooping point.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a power supply device,
In particular, it relates to a power supply device provided with power saving and overcurrent protection means.

[0002]

2. Description of the Related Art As shown in FIG.
A control voltage for inputting the switched input voltage 1 to the primary winding 51 to output the output voltages V1 and V2 to the secondary winding 52 and controlling the input of the input voltage 1; First tertiary winding 5 for outputting each drive voltage
A transformer 5 provided with the first and second tertiary windings 532;
The drive voltage output from the second tertiary winding 532 of the transformer 5 is rectified D2 and output by the first transistor Q1, and the control voltage output from the first tertiary winding 531 is rectified D1 and Upon receiving the power saving signal 8 from the drive circuit 4 and the host system, the output voltages V1 and V1
And a transmission circuit connected between the secondary circuit 7 and the output voltage V1 for detecting an overcurrent of the power saving signal 8 and the output voltage V1 and outputting an overcurrent signal. A coupler PCT, a receiving photocoupler PCR that receives the power saving signal and the overcurrent signal output from the transmitting photocoupler PCT, and an output voltage of the receiving photocoupler PCR controls the input voltage 1 to save power and overload. And a primary circuit 3 for performing current protection.

Further, the operation of the conventional power supply device is performed by a secondary circuit 7 receiving a power saving signal 8 from a host system.
The output voltage V1 is reduced to the output voltage V2 through the transmitting photocoupler PCT, and the output voltage V1 is reduced to reduce the output voltage of the first tertiary winding 531. At this time, the primary circuit 3 stops operating. So that the second tertiary winding 53
2, the supply of the driving voltage starts and the power saving operation is maintained.

On the other hand, when the output voltage V1 enters an overcurrent state, the output voltage V1 decreases with the overcurrent, the output voltage of the first tertiary winding 531 also decreases, and the second tertiary winding 532
Then, power supply to the primary circuit 3 starts, and the output voltage V1 starts to stabilize at the output voltage V2 regardless of the overcurrent state, and the droop point at the time of the overcurrent operation is extended.

[0005]

In this conventional power supply device, when the output terminal is in an overcurrent state, power supply from the tertiary winding of the transformer to the first circuit is started as in the case of power saving operation, and a droop point occurs. Is extended, and there is a problem that a droop point is extended by performing overcurrent protection.

Accordingly, an object of the present invention is to provide a power supply device that performs power saving and operates normally in overcurrent protection.

[0007]

In order to solve the above-mentioned problems, a power supply device according to the present invention inputs a switched input voltage to a primary winding and outputs an output voltage to a secondary winding.
A control voltage for performing input control of the input voltage, and a first control signal for outputting a drive voltage when the control voltage decreases.
A transformer provided with a secondary winding and a second tertiary winding; a drive voltage output from the second tertiary winding of the transformer, rectified and output by a first transistor; A drive circuit for rectifying and smoothing the control voltage output from the secondary winding; a secondary circuit for receiving the power saving signal from the host system and controlling the output voltage;
A transmitting photocoupler connected between the output terminal of the next winding and detecting an overcurrent of the power saving signal and the output voltage and outputting an overcurrent signal; and the transmitting photocoupler detected by the transmitting photocoupler. A receiving photocoupler that receives a power signal and an overcurrent signal, a primary circuit that controls the input voltage to perform power saving and overcurrent protection with the receiving photocoupler, and a detection diode that detects the potential of the receiving photocoupler. When the detection diode detects a predetermined voltage or more, the second transistor is turned on to turn off the first transistor, the driving voltage supplied to the primary circuit is stopped, and an overcurrent protection operation is performed. A control circuit for supplying a drive voltage to the primary circuit when the detection diode detects a voltage lower than a predetermined voltage and performing a power saving operation. To.

[0008]

Next, a power supply device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a power supply device according to an embodiment of the present invention.

A power supply according to an embodiment of the present invention comprises:
As shown in FIG. 1, the switched input voltage 1 is 1
Input to the secondary winding 51 and output voltages V1, V to the secondary winding 52.
2 and a control voltage for performing input control of input voltage 1 and a first tertiary winding 531 and a second tertiary winding 532 for outputting a drive voltage when the control voltage decreases. A transformer 5 and a second tertiary winding 5 of the transformer 5
A drive circuit 4 for rectifying D2 the output of the drive voltage output from the second rectifier D2 and outputting the rectified output voltage from the first transistor Q1, and rectifying D1 and smoothing the control voltage output from the first tertiary winding 531; A secondary circuit 7 that receives the power-saving signal 8 and controls the output voltages V1 and V2, and is connected between the secondary circuit 7 and the output voltage V1, and is overcurrent of the power-saving signal 8 and the output voltage V1. , An output photocoupler PCT for detecting an overcurrent signal and outputting an overcurrent signal; a photocoupler PCR for receiving the power saving signal and the overcurrent signal detected by the output photocoupler PCT;
The primary circuit 3 which controls the input voltage 1 by the CR to perform power saving and overcurrent protection, and the potential of the receiving photocoupler PCR is detected by the detection diode ZD1, and when the detection diode ZD1 detects a predetermined voltage or more. Turning on the second transistor Q2 and turning off the first transistor Q1,
The driving voltage supplied to the next circuit 3 is stopped to perform an overcurrent protection operation, and when the detection diode ZD1 detects a predetermined voltage or less, the driving voltage is supplied to the primary circuit 3 to perform a power saving operation. And a control circuit 2.

Next, the operation of the power supply according to one embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the operation of the power supply device according to the embodiment of the present invention is as follows. A switched input voltage 1 is input to a primary winding 51 and an output voltage V1, When the output voltages V1 and V2 are stabilized by the secondary circuit 7 and transmitted to the primary circuit 3 through the transmitting photocoupler PCT and the power saving signal 8 from the host system is received, the secondary circuit 7 is output. , The voltage of the output voltage V1 is reduced to the output voltage V2, and the operation shifts to the power saving operation. When the voltage of the output voltage V1 decreases, the output voltage of the first tertiary winding 531 decreases and the first transistor Q1 Operates with the resistor R4 and the constant voltage diode ZD2, and the second tertiary winding 532
, The power supply to the primary circuit 3 is started and the voltage of the receiving photocoupler PCR does not increase, and the power saving operation is maintained.

On the other hand, during the overcurrent protection operation, the output voltage V1
When the output voltage of the first tertiary winding 531 of the transformer 5 decreases due to a decrease in the voltage of the transformer 5, power supply from the second tertiary winding 532 starts, but no current flows through the transmitting photocoupler PCT. The detection diode ZD1 detects an increase in the voltage of the reception photocoupler PCR, turns on the second transistor Q2, turns off the first transistor Q1, and cuts off the power supply from the second tertiary winding 532.

[0014]

As described above, according to the power supply device of the present invention, the transition to the power saving operation and the return can be performed during the power saving operation, and the control circuit connected to the primary circuit during the overcurrent protection operation. Since the supply power is cut off, there is an effect of preventing the extension of the droop point during the overcurrent protection operation.

[Brief description of the drawings]

FIG. 1 is a block diagram of a power supply device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional power supply device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input voltage 2 Control circuit 3 Primary circuit 4 Drive circuit 5 Transformer 6 Rectifier smoothing circuit 7 Secondary circuit 8 Power saving signal 51 Primary winding 52 Secondary winding 531 First tertiary winding 532 Second 3 Secondary winding C1 Control circuit (capacitor) C2 Drive circuit (capacitor) R1, R3 Control circuit (resistance) R2 Primary circuit (resistance) R4 Drive circuit (resistance) R5 Secondary circuit (resistance) Q1 Drive circuit (first transistor) ) Q2 control circuit (second transistor) ZD1 control circuit (detection diode) ZD2 drive circuit (constant voltage diode) D1, D2 drive circuit (diode) PCR reception photocoupler PCT transmission photocoupler

Claims (1)

[Claims] 1. A control voltage for inputting a switched input voltage to a primary winding, outputting an output voltage to a secondary winding, and performing input control of the input voltage, and driving when the control voltage decreases. A transformer provided with a first tertiary winding and a second tertiary winding each outputting a voltage, and a second
And a drive circuit for rectifying the drive voltage output from the tertiary winding and outputting the rectified drive voltage from the first transistor, and rectifying and smoothing the control voltage output from the first tertiary winding. A secondary circuit that receives the power saving signal and controls the output voltage, and is connected between the secondary circuit and an output terminal of the secondary winding, and outputs the power saving signal and an overcurrent of the output voltage. A transmitting photocoupler that detects and outputs an overcurrent signal, a receiving photocoupler that receives the power saving signal and the overcurrent signal detected by the transmitting photocoupler, and controls the input voltage by the receiving photocoupler. A primary circuit that performs power saving and overcurrent protection, and a potential of the receiving photocoupler is detected by a detection diode. When the detection diode detects a predetermined voltage or more, a second transistor is turned on. Off the first transistor,
The drive voltage supplied to the primary circuit is stopped to perform an overcurrent protection operation, and when the detection diode detects a predetermined voltage or less, a drive voltage is supplied to the primary circuit to perform a power saving operation. A power supply device comprising: a power supply device;