JPH0934569A - Regulator circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple and inexpensive regulator circuit which contains a current booster circuit having a function that protects the regulator circuit when a load circuit has a short-circuit. SOLUTION: When a transistor to which a normal time trigger pulse is applied is turned on in a power-on mode, a regulator IC operates and the stabilized output is supplied from an output terminal. At the same time, the potential of the stabilized output is fed back and the regulator IC carries on its operation to keep the stabilized output. Then the feedback of the stabilized output is not carried out any more when the load circuit of the output terminal has a short. Thus a regulator circuit containing a current booster circuit prevents the subsequent supply of output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regulator circuit such as a regulator circuit with a current boost circuit having a function of protecting the circuit when a load circuit is short-circuited.

[0002]

2. Description of the Related Art An example of this type of conventional circuit is shown in FIG.
And the one shown in FIG. 3 has been proposed.

[0003]

In such a conventional technique, for example, in the case of the circuit of FIG. 2, even if the output terminal is short-circuited, a regulator IC which is a current limiting circuit.
Because the current continues to flow from the output terminal due to the operation of, the electric power is wasted and the resistors etc. generate heat.
Especially, it is not preferable in a small portable electronic device. Further, in the case of the circuit of FIG. 3, the circuit configuration becomes complicated and the cost increases.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems of the prior art, and at the time of power-on, a signal supplied to the input terminal applies a trigger pulse for a specified time so that a transistor is activated. When turned on, the regulator IC operates, and a stabilized output is supplied from the output terminal through the current boost transistor, and at the same time, the potential of this output is fed back to keep the transistor turned on.
The regulator circuit with the current boost circuit keeps the output stable by keeping the output stable, and when the load circuit at the output terminal is short-circuited, there is no feedback from the output terminal to the transistor, thereby preventing further output supply. And other regulator circuits are provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram of an embodiment of the present invention, and an operation in such a circuit configuration will be described. In FIG. 1, when the power is turned on, a signal is supplied to the input terminal. Therefore, a trigger pulse is generated at the point A for the time of C1.R1 and Tr1 is turned on.
Since the control terminal B of C becomes Low, the regulator IC operates, and a stabilized output is supplied from the output terminal through the current boost transistor Tr2. At the same time, the potential of this output is fed back to the point A through the resistor R2 and Tr1 is kept ON, so that the stabilized output is maintained.

Next, when the load circuit at the output terminal is short-circuited to the ground or the like, feedback from the output terminal to the point A through the resistor R2 is lost, so Tr1 is turned off and the control terminal B of the regulator IC becomes High. The IC shuts down and acts to prevent further output from the output terminals to prevent damage to the circuit.

[0007]

According to the circuit configuration of the present invention, a regulator circuit with a current boost circuit having a function of protecting the circuit when the load circuit is short-circuited can be put into practical use easily and inexpensively.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram of an embodiment of the present invention.

FIG. 2 is a conventional circuit configuration diagram.

FIG. 3 is another conventional circuit configuration diagram.

[Explanation of symbols]

 1 Regulator IC Tr1 transistor Tr2 Current boost transistor

Claims (1)

[Claims] 1. At power-on, a regulator IC is activated by a trigger pulse being applied for a specified time by a signal supplied to an input terminal to turn on a transistor, and stabilized from an output terminal through a current boost transistor. At the same time when the output is supplied, the potential of this output is fed back to keep the transistor ON, the regulator IC continues to operate and the stabilized output is maintained, and when the load circuit at the output terminal is short-circuited, the output is output. A regulator circuit characterized in that feedback from the terminal to the transistor is eliminated and further output supply is blocked.