JPH06217534A - Regulated power supply - Google Patents

Abstract

PURPOSE:To enable a regulated power supply which uses a photocoupler in a control circuit to inform a control limit caused by the deterioration of the photocoupler through an alarm. CONSTITUTION:The circuit which feeds back the error information of its out voltage to a voltage adjusting circuit by using a photocoupler 11 is provided with a detecting means 12 which detects the input current of the input section of the coupler 11 and an alarm generating means 13 which generates an alarm when the input current detected by means of the means 12 exceeds a fixed value connected in series with the input section of the coupler 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stabilized power supply circuit equipped with an alarm circuit for predicting a power supply control limit in a power supply for electronic equipment. With the increase in the amount of information handled by communication devices, information processing devices, etc., the social impact caused by the failure of the power supply device used for them has become more and more important. Therefore, the demand for the reliability of the power supply device is further increasing.

[0002]

2. Description of the Related Art In order to meet this demand, a conventional example of a stabilized power supply using a photocoupler in a control circuit, which is widely used today, is shown in FIG. In the figure, 1 is a primary side power supply, which supplies electrical energy (voltage V _in ), 2
Is a load, which receives a stabilized voltage, 3 is a transformer, which converts the primary side power supply voltage into a voltage required by the secondary side load, 4 is a switching circuit (SW),
A pulse width modulator (P) for converting the primary side DC input to pulse power for intermittent voltage conversion by a transformer
WM), which changes the output voltage of the transformer 3 by changing the pulse width of the pulse power converted by the switching circuit 4, 6 is a rectifier, which converts AC to DC, and 7 is a smoothing capacitor. , Which removes the AC component of the rectifier output, 8 is an error amplifier (AMP1), which is the sign of the difference voltage between the actual value of the secondary side output DC voltage and the target value (V _REF ) of the secondary side output DC voltage The output current is increased or decreased from a constant value by 10; an overvoltage protection circuit for protecting the load from the overvoltage; 11 a photocoupler (PC) for coupling the control current by optical means; It is the entire circuit configuration of the stabilized power supply.

When the actual output voltage becomes higher than the target value due to the fluctuation of the voltage V _in of the primary side power supply or the fluctuation of the load 2, the primary current of the PC 11 is increased to increase the PWM.
The drive voltage of 5 is increased. As a result, the pulse width of the primary current of the transformer 3 decreases, the secondary output of the transformer 3 decreases, and the rectified output approaches the target value V _REF . When the actual output voltage becomes lower than the target value, adjustment in the opposite direction is performed.

The above adjustment is guaranteed when the current transfer rate of the PC is maintained in a certain range, but when the current transfer rate of the PC deviates from the certain range and deteriorates, the output voltage is increased. Even if the voltage rises, the current cannot flow to the secondary side of the PWM 5, and the voltage cannot be suppressed. As a result, the output voltage supplied to the load 2 reaches an overvoltage. Therefore, an overvoltage protection circuit is provided.

[0005]

However, the voltage limitation by the overvoltage protection circuit is only a temporary measure and is essentially different from the stable operation, and the original purpose of supplying a stable voltage to the load is to be achieved. I can't.

It is an object of the present invention to detect the deterioration of the current transfer rate of the photocoupler, display that the control limit has been reached before the output voltage rises, and inform the safety time of the power supply circuit.

[0007]

FIG. 1 is a diagram for explaining the principle of the present invention. In the figure, 1 is a primary power supply, which supplies electrical energy (voltage V _in ), 2 is a load, which requires the supply of a stabilized voltage, 3 is a transformer, and the primary power supply voltage To convert the voltage to the voltage required by the secondary load,
Reference numeral 4 is a switching circuit (SW), which intermittently converts the DC input on the primary side to convert into pulse power capable of voltage conversion by a transformer, and 5 is a pulse width modulator (PWM), which is converted by the switching circuit 4. The one that changes the output voltage of the transformer 3 by changing the pulse width of the pulse power, 6 is a rectifier that converts AC into DC, 7 is a smoothing capacitor that removes the AC component of the rectifier output,
Reference numeral 8 denotes an error amplifier (AMP1), which increases or decreases the output current from a constant value according to the sign of the voltage difference between the actual value of the secondary output DC voltage and the target value (V _REF ) of the secondary output DC voltage, Reference numeral 11 is a photocoupler (PC), which couples the control current by optical means, 12 is a PC input current level detection circuit, which drives an alarm display circuit according to the value of the PC input current, and 13 is an alarm display Reference numeral 200 is a circuit for indicating deterioration of the PC, and 200 is the entire circuit configuration of the stabilized power supply.

When the PD deteriorates, the PD current for keeping the output voltage within a predetermined range increases outside the fixed range, and therefore the PC level is detected so that an alarm is displayed corresponding to the increased value. Set the operating point of the circuit.

[0009]

According to the present invention, as shown in FIG. 1, the current level detection circuit 12 and the alarm display circuit 13 of the PC are added to the conventional configuration shown in FIG. Therefore, the operation principle of the normal adjustment is the same as in the case of FIG. Hereinafter, the PC current level detection circuit 12 and the alarm display circuit 1 peculiar to the present invention
The operation of No. 3 will be described.

The limit current value (I
_PCMAX ) causes the voltage generated in the resistor 121 built in the PC input current detection circuit 12 to change to the PC input current detection circuit 1
When the base-emitter voltage (V _be ) of the transistor Q1 built in 2 is exceeded, the transistor Q1 becomes conductive and current flows in the alarm circuit. The current is adjusted by selecting the value of the resistor 132 built in the alarm display circuit 13 so that the light emitting element 132 built in the alarm display circuit 13 emits light at an appropriate level.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 shows a first embodiment of the present invention. In the figure, 10 is an overvoltage protection circuit, and 201 is the entire circuit configuration of a stabilized power supply. Other elements are the same as the principle explanatory diagram of the present invention in FIG. The normal operation is the same as in the case of the conventional example of FIG. PC11
When the current exceeds the constant value just before the limit value of the normal operation range, the transistor Q1 becomes conductive, and the light emitting element 132 of the alarm display circuit emits light. This example of the structure of the present embodiment takes measures against overvoltage in the case of oversight of the alarm display and failure of the alarm display circuit.

FIG. 3 shows a second embodiment configuration example. 1 in the figure
Reference numeral 4 is a second photocoupler, the input part of which is connected in series to the alarm display circuit 13 as the load of the input detection means 12, and the output part is connected in parallel with the output part of the first photocoupler 11. . Further, 202 is the entire circuit configuration of the stabilized power supply. Others are the same as the principle configuration diagram of FIG. In the configuration example of the present embodiment, when the current value of the PC 11 is equal to or higher than a certain value, Q1 conducts, an alarm is issued, a current flows through the PC 14, and a new feedback path via the PC 14 is formed to prevent an increase in the output voltage. And encourage preventive maintenance. At the same time, until the preventive maintenance is taken, a new feedback path is used to stabilize the output voltage and allow time for the maintenance to start. It is needless to say that the configuration example of the present embodiment may also be provided with an overvoltage protection circuit as in the first configuration example.

FIG. 4 shows a third example of the configuration. 9 in the figure
A and 9B are diodes for preventing mutual interference between the current stabilizing power source 203A and the pre-stabilizing power source 203B, 1
An auxiliary power supply circuit 4 supplies a power supply voltage V _CC for PWM, PC and the like. The display of the other components is the same as that of the above-described embodiments. The working stabilizing power supply 203A has a circuit substantially similar to that of the second embodiment, except that the output of the second photocoupler 14 is connected to the standby power supply 2A.
It is connected to the auxiliary power supply circuit 14 in 03B and used to turn on / off the auxiliary power supply output voltage V _CC .

The pre-stabilization power source 203B is always connected in parallel with the current stabilization power source 203A, but the auxiliary power output voltage V _CC is kept off until the current stabilization power source 203A issues an alarm. The pre-stabilized power supply 203B does not provide output to the load. When the first photocoupler 11 of the working stabilized power supply 203A deteriorates, the input detection means 1
The output current of the second photocoupler 14 is increased, the output part of the second photocoupler 14 is turned on, and the auxiliary power supply circuit 14 in the pre-stabilized power supply 203B starts to supply the power supply voltage V _CC . The output supply of is started. On the other hand, in the active stabilizing power supply 203A, the overvoltage protection circuit 10A operates to stop the output supply to the load. It is possible to remove the working stabilizing power supply 203A that has deteriorated in this state.

When the pre-stabilization power source 203B is deteriorated, the output of the pre-stabilization power source is cut off by the overvoltage protection circuit 10B. In addition, after removing the current stabilizing power source 203A, the normal stabilizing power source is inserted, and the failback for stopping the activation of the preliminary stabilizing power source is performed by temporarily removing the preliminary stabilizing power source.
This can be easily done by re-inserting.

[0016]

According to the present invention, as described above,
By detecting the control limit of the power supply in advance and prompting for maintenance, or by detecting that the control limit has been approached and changing the return route and starting the standby power supply, it becomes possible to prevent device failure in advance. It greatly contributes to maintaining and improving the reliability of machines and information processing equipment.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a structural example of a first embodiment of the present invention.

FIG. 3 is a structural example of a second embodiment of the present invention.

FIG. 4 is a structural example of a third embodiment of the present invention.

FIG. 5 is a conventional configuration example.

[Explanation of symbols]

1 Primary Power Supply 2 Load 3 Transformer 4 Switching Circuit (SW) 5 Pulse Width Modulator (PWM) 6, 9A, 9B Rectifier 7 Smoothing Capacitor 8 Error Amplifier (AMP1) 10, 10A, 10B Overvoltage Protection Circuit 11 Photocoupler ( PC) 12 PC input current level detection circuit 13 Alarm display circuit 14 Auxiliary power supply circuit 100, 200, 201, 201, 203A, 203B
Regulated power supply

Claims (3)

[Claims] 1. A stabilized power supply circuit for feeding back error information of an output voltage to a voltage adjusting circuit using a photocoupler,
Input detection means (12) for detecting the input current of the input part of the feedback photocoupler (11) in series, and an alarm is issued when the input current detected by the input detection part exceeds a certain value. A stabilized power supply circuit comprising an alarm generating means (13). 2. The second photocoupler (14) according to claim 1, wherein the input part of the photocoupler (14) is connected to the input detecting means (12) and the output part is connected to the first photocoupler (14). By connecting the output part of 11) in parallel,
A stabilized power supply circuit characterized by forming an output voltage feedback path. 3. The second photocoupler (14) according to claim 1, wherein the input part of the photocoupler (14) is connected to the input detecting means (12), and the output part serves as a starting means for the standby power supply. A stabilized power supply circuit characterized by being used.