JPH02266825A - Constant voltage power source - Google Patents

Abstract

PURPOSE:To prevent breakdown by passing an OFF command signal fed from the input terminal of a primary power source through a constant current circuit, upon detection of overcurrent, and feeding an OFF command signal having constant level against fluctuation of primary source voltage to a command circuit thereby interrupting output to a load. CONSTITUTION:When pulse signals are applied onto an OFF command terminal 4 and constant voltage is provided through an output terminal 2 to a load, an H level signal is fed from a current judging circuit 9 to a switch 11 if load current exceeds over an allowable level due to abnormality, such as short circuit fault, of the load and the switch 11 is turned ON to conduct a Tr 13. But since the voltage across a constant current setting resistor 14 is maintained constant by the voltage of a reference voltage source 12 and the bias voltage between the base and emitter of the Tr 13, current flowing through the Tr 13 to the OFF command input terminal of a command circuit 6 is maintained constant regardless of the primary source voltage. Consequently, the command circuit 6 produces an L level signal and a voltage stabilizing circuit 7 interrupts provision of output thus protecting the constant voltage power source.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to, for example, a constant voltage power supply device for a satellite-mounted communication device;
In particular, it relates to overcurrent output prevention.

[Conventional technology]

FIG. 2 is a block diagram of a constant voltage power supply device using a conventional overcurrent output prevention circuit. In the figure (ri is the input terminal,
(2) is the output terminal, +3) (3B is the ground terminal.

(41 is an on command terminal, (51d is an off command terminal.

+61 ij Command circuit connected to the above on-command terminal (4) and off-command terminal (51), +71i
J is connected to the above input terminal (l), the ground terminal +31 f31' and the output terminal of the command circuit (6); 9 voltage stabilization circuit; (8) is the output terminal of the above voltage stabilization circuit (7) and the above output terminal A current detector inserted between (2), (9)
is a current determination circuit connected to the current detector (81), a
l is the upper Bioff command circuit (51 command circuit (6
A backflow prevention diode inserted between the off command input terminals of 1 and 1, a? lH A changeover switch that changes the connection between the input terminal [11 and the off command input terminal of the command circuit 16+] is an energy bank capacitor inserted between the common terminal of the changeover switch aη and the ground terminal.

A conventional constant voltage power supply is configured as described above, and normally the changeover switch αn is connected to the ON side.

The energy bank capacitor G8 has an input terminal fil.
Energy is supplied from the primary power source connected to the ground terminal (3) and the charge is stored.

When a pulse signal is applied to the on-command terminal (4), an H level signal is output from the command circuit +61.

The voltage stabilizing circuit (71) supplies a constant voltage to the load connected to the output terminal (2) and the ground terminal [31' K via the current detector (8). is outputted to the signal t-current determination circuit (91) according to the output current, and as the output current increases, the output signal level of the current detector (81) also increases.

When an abnormality such as a short-circuit failure occurs in the load and the output current exceeds the allowable value, a signal level exceeding the threshold set in the current determination circuit (9) corresponding to the output current allowable value is detected by the current detector (8). ) because it is input more.

The current determination circuit outputs the +91iH level signal to the changeover switch αD.

The changeover switch an is switched to the OFF side while receiving an H level signal from the current determination circuit (9).

As a result, the energy stored in the energy capacitor fia is released to the upper gQ command circuit (61) in the form of an off command.

The command circuit (6) outputs an L level signal to the voltage stabilizing circuit (7), and the voltage stabilizing circuit +71 stops outputting to protect the constant voltage power supply.

The backflow prevention diode αυ is the command terminal (5) when the energy of the energy bank capacitor is turned off.
To prevent escape to external equipment connected to the above off command terminal +51K pulse signal is applied,
A pulse signal is input to the command circuit (6:) via the backflow prevention diode αα.

As a result, the voltage stabilizing circuit (7) stops outputting.

[Problem to be solved by the invention]

In the conventional constant voltage power supply device as described above, voltage fluctuations in the primary power supply directly result in fluctuations in the level of the off command signal at the time of overcurrent detection, so the primary power supply is an unregulated bus type primary power supply where the primary power supply voltage changes significantly. When used in an off-command terminal, there is a problem that there is a large difference in level between the off-command signal input from the outside through the off-command terminal and the off-command signal at the time of overcurrent detection, making it incompatible with the command circuit.

This invention was made to solve this problem, and when an overcurrent is detected, by passing the off command signal supplied from the input terminal of the -order power supply through a constant current circuit,
- The purpose of this invention is to supply an off command signal at a constant level to the command circuit even when the power supply voltage fluctuates, stop output to the load, and prevent damage to the constant voltage power supply.

[Means to solve the problem]

The constant voltage power supply device according to the present invention includes a switch that performs 0N10FF in response to a signal from a current determination circuit, and a reference voltage source, a constant current establishing resistor, A constant current circuit consisting of a bias resistor and a PNP transistor is inserted.

[Effect]

In this invention, in the event of an abnormality such as a load short-circuit failure, when the load current exceeds the allowable value, the PNP in the constant current circuit
When the transistor becomes conductive, constant tltR flows into the off-command input terminal of the command circuit through the constant current establishment resistor, stopping the operation of the voltage stabilizing circuit and preventing damage to the constant voltage power supply.

〔Example〕

FIG. 1 is a block diagram of a constant voltage power supply device showing an embodiment of the present invention, and (l) to a11 are completely the same as the conventional constant voltage power supply device described above. a11I/'i A switch that performs 0N10FF t- according to the signal of the current judgment circuit (9), (19 is a PNP transistor α3 that conducts when the reference voltage source α2 and switch 1111 are ON.) Constant current establishment resistor α4. Bias resistance It is a constant current circuit consisting of.

In the constant voltage power supply device configured as described above, a negative power source is connected to the input terminal (1) and the ground terminal (3),
When a load is connected to the output terminal (2) and the ground terminal (3-bit) and a pulse signal is applied to the on-command terminal (4), an H level signal is output from the command circuit (61) and the voltage stabilization circuit (7 ) to the output terminal (2
) supplies constant voltage to the load. Off command terminal (5
), when a pulse signal is applied to the command circuit (6), 5L
The level signal is output, the voltage stabilizing circuit (7) stops operating, and power supply to the load from the output terminal (21) stops.

A pulse signal is applied to the on-command terminal (41).

When a constant voltage is being output to the load from the output terminal (2).

When an abnormality such as a short circuit failure occurs in the load and the load current exceeds the allowable value, the current judgment circuit (9) switches the switch 11υKH.
A level signal is output.

The switch aυ is turned on while receiving the H level signal from the current determination circuit (9). As a result, the pPNP transistor α3 becomes conductive, but the voltage value of the reference voltage source α2 and the PN
Due to the bias voltage value between the base and emitter of the P transistor α3, the voltage across both parts of the constant current establishing resistor α4 is constant, so the current flowing into the off command input terminal of the command circuit +61 through the PNP transistor +13i is as follows.
-Always constant regardless of the secondary power supply voltage.

Upon receiving this signal, the command circuit +61 outputs a full L level signal, and the voltage stabilizing circuit (7) stops its output to protect the constant voltage power supply.

〔Effect of the invention〕

As explained above, this invention uses a simple constant current circuit to generate 8 peaks of the off command signal at the time of overcurrent detection.
- It is stabilized at a constant level regardless of fluctuations in the power supply voltage.

By setting the signal level so that it is at the same time as the off command signal from the outside, compatibility with the command circuit can be achieved, and the effect is that it is possible to protect the constant voltage power supply when a load current exceeding the allowable value flows. There is.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a constant voltage power supply device showing an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional constant voltage power supply device. In the figure, (1) is an input terminal, (2) is an output terminal, (
31+31't'j ground terminal, f4+1d on command terminal, +51 [off command Koko, +81 fl command circuit, (7) is voltage stabilization circuit, +81 [current detector, +91i current judgment circuit. aG is a backflow blocking diode, aυ is a switch, +1
2 is a reference voltage source, (13 is a PNP transistor, C14
is a resistor for establishing a constant current, the target is a bias resistor, the utiFi constant current circuit, α1 is a changeover switch, and aS is a capacitor for an energy bank. Note that the same or corresponding parts in FIG. 9 are designated by the same reference numerals.

Claims (1)

[Claims] An input terminal, an output terminal, a ground terminal, a voltage stabilizing circuit inserted between the input terminal and the output terminal, an on command terminal, an off command terminal, and the on command. A command circuit is connected to the terminal and an off command terminal and outputs an on/off signal to the voltage stabilizing circuit.A primary power supply is connected between the input terminal and the ground terminal, and a command circuit is connected between the output terminal and the ground terminal. A constant voltage power supply device that supplies a predetermined voltage to the load when a load is connected to the on-command terminal and a pulse signal is input to the on-command terminal, and stops operation when a pulse signal is input to the off-command terminal, a current detector inserted between the output end and the output terminal of the voltage stabilization circuit, which converts the output current value into a level signal and outputs it;
High when the output level of the current detector above is greater than the threshold
a current determination circuit that outputs a level signal; a switch that has one terminal connected to the input terminal and turns on upon receiving a significant signal from the current determination circuit; and a reference that is connected to the other terminal of the switch. a voltage source, a constant current establishing resistor, a PNP transistor having a base connected to the reference voltage source, an emitter connected to the constant current establishing resistor, and a collector connected to the off command input terminal of the command circuit; a constant current circuit consisting of a bias resistor inserted between the base of the circuit and the ground terminal, and a constant current circuit inserted between the off command terminal and the off command input terminal of the command circuit with the anode connected to the off command terminal. A constant voltage power supply device that is equipped with a backflow prevention diode and automatically shuts down when the output current exceeds a permissible value.