JPH0622451A - Erroneous function preventive circuit for multi-output power supply load device - Google Patents

Abstract

PURPOSE:To prevent erroneous function of load device due to lag of output voltage falling time upon turn OFF of power under light load state. CONSTITUTION:A Zener diode D1 detects voltage and a transistor Q turns a relay RL ON/OFF. An erroneous function preventive circuit 4 for opening/ shorting the output depending on make/break of relay contact r1 is inserted between a power supply unit 3 and a load device control section 7 in order to control a sequence between the output voltages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to prevention of malfunction of a load device by sequence control between outputs of a multi-output power supply.

[0002]

2. Description of the Related Art A conventional power supply load device malfunction prevention circuit for a power supply unit will be described with reference to the drawings.

FIG. 3 is a block diagram of a conventional power supply and load device control circuit, and FIG. 4 is a diagram showing a power supply sequence of the load device control section 7 of FIG.

In FIG. 3, the conventional power supply and load device control circuit is connected to an AC power supply 1, a switch 2, a power supply unit 3, a load device control section 7 having a control IC 5 and an RS232C6, and a modem. And a data branching unit (hereinafter referred to as DBU) 10 and terminal units 12a and 12b.

Here, the fall time of the output voltage when the power supply unit 3 is OFF is defined by the discharge time of the output capacitors C1 and C2 in the rated load state, and as shown in FIG. The load device controller 7 is directly connected to the power supply unit 3, and when the power is turned off by the switch 2, the power supply unit 3 is stopped and the voltage remaining in the power supply unit output capacitors C1 and C2 is discharged to the load. At this time, the DBU connected to the modem via RS232C6
When the load of the terminal devices 12a and 12b branched by 10 is in a light load state, it takes a long time to discharge the output capacitors C1 and C2, resulting in a gentle fall as shown in FIG.

[0006]

In the above-described conventional power supply load device malfunction prevention circuit for a power supply unit, the fall time of the output voltage at a light load is not specified, and as shown in FIG. In the unit 3, when the + 5V load is the rated load and the + 12V load is a light load, + 5V falls within the specified time, but + 12V is a light load, so the output capacitor C2 is not easily discharged and the voltage remains. , RS12C of + 12V load sends an erroneous output to the DBU 10 as shown in FIG. 4, and when another connected terminal device is communicating, there is a problem that the retry becomes a load and the line becomes abnormal.

An object of the present invention is to eliminate the above-mentioned drawbacks by inserting a malfunction prevention circuit having a sequence control function into a power supply unit and a load device control section, and causing other outputs to fall earlier than the control system output when the power is turned off. Another object of the present invention is to provide a multi-power supply load device malfunction prevention circuit that eliminates malfunctions of a load device due to delay of fall time of output voltage when power is turned off in a light load state.

[0008]

A multiple power supply load device malfunction prevention circuit of the present invention is a load device control for controlling a power supply unit having multiple output power supplies and a load device to which a power supply voltage is supplied from the power supply unit and which is connected. And a means for performing sequence control between the output voltages of the power supply unit.

[0009]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram of a power supply and load device control circuit to which a multiple power supply load device malfunction prevention circuit according to an embodiment of the present invention is applied, and FIG. 2 is a diagram showing a power supply sequence of a load device control section 7 of FIG. Is.

In FIG. 1, a power supply and load device control circuit to which the multiple power supply load device malfunction prevention circuit of this embodiment is applied includes an AC power supply 1, a switch 2, a power supply unit 3, and
Malfunction prevention circuit 4 having control circuit 9, load device control section 7 having control IC 5 and RS232C6, and DBU
RS output 8 to 10.

Here, the AC power source 1 is input and DC + 5
Insert the malfunction prevention circuit 4 between each output terminal of the power supply unit 3 that outputs V and + 12V and the input terminal of the load device control section 7 to create a sequence for the DC + 5V and DC + 12V outputs, and to make DC + 12V faster when DC + 5V falls. RS232 which is a load of DC + 12V output
The erroneous output of C6 is eliminated, and the line failure of another terminal device (not shown) connected by the DBU 10 is prevented.

Next, details of the sequence control operation will be described.

When the switch 2 is turned on, the AC power supply 1 is input to the power supply unit 3, the power supply unit 3 starts operating, and outputs DC + 5V and + 12V. In the malfunction prevention circuit 4 connected to the output terminal of the power supply unit 3, DC + 5V supplied to the control IC 5 is a constant voltage diode D1.
When the voltage exceeds the Zener voltage of, the base of the transistor Q is driven through the resistor R1 and the transistor Q is turned on. When the transistor Q turns ON, the relay RL turns ON, the relay contact rl switches to the a side, and DC + 1
2V is supplied to RS232C6 (load side). Therefore, the power supply unit 3 relays the malfunction prevention circuit 4 and supplies DC + 5V and + 12V to the load device controller 7. When the switch 2 is turned off in this state, the power supply unit 3 is stopped and DC + 5V and + 12V droop during the discharge time of the output capacitors C1, C2 + C3 and the load device controller 7, respectively. The operation of the malfunction prevention circuit 4 at the time of OFF is that when the voltage of the DC + 5V output drops and becomes equal to or lower than the Zener voltage of the quiescent voltage diode D1, the base of the transistor Q cannot be driven and the transistor Q does not operate.
Turns off. When the transistor Q is turned off, the voltage applied to the relay RL also disappears and the relay contact rl
Is switched to the b side, the supply of the DC + 12V output voltage is dropped, and the voltage remaining in the input capacitor C3 of the load device control unit 7 is discharged through the discharge resistor R3. Therefore R
The fall of + 12V input to S232C6 is determined by the discharge time of the input capacitor C3 and the discharge resistor R3 of the load device controller 7, which is a very small time constant compared with the output capacitor C1 of the power supply unit 3. , Get off quickly. FIG. 2 shows a power supply sequence of the load device controller 7 that relays the malfunction prevention circuit 4. DC +
When 5V becomes the Zener voltage 11, after operation time t, DC
+ 12V falls and RS232C6 erroneous output disappears.

[0015]

As described above, the multiple power supply load device malfunction prevention circuit according to the present invention has a multi-output power supply of +5 V and +12.
A malfunction prevention circuit having a sequence control function having a control circuit for controlling a falling sequence between V output voltages, a relay contact for speeding up the falling at a light load, and a discharge resistor is provided for controlling a power supply unit and a load device. When the power supply is turned off in a light load state, the malfunction of the load device due to the delay of the fall time of the output voltage can be prevented by inserting the power supply into the control unit and turning off the other output earlier than the control system output when the power is turned off. The effect is that you can do it.

[Brief description of drawings]

FIG. 1 is a block diagram of a power supply and load device control circuit to which a multiple power load device malfunction prevention circuit according to an embodiment of the present invention is applied.

FIG. 2 is a diagram showing a power supply sequence of a load device control section 7 in FIG.

FIG. 3 is a block diagram of a conventional power supply and load device control circuit.

FIG. 4 is a diagram showing a power supply sequence of the load device control section 7 of FIG.

[Explanation of symbols]

 1 AC power supply 2 Switch 3 Power supply unit 4 Malfunction prevention circuit 5 Control IC 6 RS232C 7 Load device control section 8 RS output 9 Control circuit 10 DBU 11 Zener voltage 12a, b Terminal device R1, R2, R3 Resistor C1, C2, C3 Capacitor D1 Zener diode D2 Diode R1 Relay (coil) rl Relay contact Q Transistor t Relay operating time

Claims (1)

[Claims] 1. A sequence between output voltages of the power supply unit between a power supply unit having a multi-output power supply and a load device control section for controlling a load device to which a power supply voltage is supplied from the power supply unit and which is connected. A multi-output power supply load device malfunction prevention circuit comprising means for performing control.