JPH05129975A - Power supply short circuit protection circuit for external unit of satellite broadcast receiver - Google Patents

Abstract

PURPOSE:To prevent undesired power and heat consumption and to inform a user of a fault by monitoring a power supply voltage fed to an external unit and stopping a power supply when a voltage differs from a reference voltage and displaying a fault message. CONSTITUTION:An unstable input voltage is applied to a voltage regulator IC2, from which a stable output voltage is fed to a BS external unit through a switch SW2. A voltage resulting from an input voltage divided by resistors 5,6 is applied to a reference voltage terminal of a voltage comparator IC3 and a voltage depending on a resistor 7 and a load is fed to a comparison terminal. When the voltage at the comparison terminal is lower than the reference voltage, an output of the IC3 goes to an H level and is inputted to the IC2, in which an internal switch is interrupted and an output voltage is not given to an external unit. Simultaneously, the output voltage is inputted to a channel selection microcomputer IC4 and a message representing a fault is displayed on a CRT. Thus, undesired power consumption and heat consumption are prevented and the user is informed of the fault.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for supplying necessary power to an external unit of a satellite broadcast receiving device.

[0002]

2. Description of the Related Art Conventionally, a 15V power supply supplied to an external unit of a satellite broadcast receiving device is composed of a power supply circuit represented by a three-terminal voltage regulator shown in FIG. 2, and an unstable input voltage is supplied to a voltage stabilizing IC1. In addition, the stabilized output is superposed on the BS external unit, that is, the antenna for satellite broadcasting through the switch 1 and supplied.

[0003]

However, in such a conventional circuit configuration, when the core wire of the antenna and the ground wire are short-circuited, the power source is not originally required in the co-listening system, and the core wire of the antenna is grounded in terms of direct current. When it was smelled, it was dealt with by the overcurrent protection characteristic / heat limiting characteristic of the IC or circuit. At this time, there was a problem that unnecessary power and heat were consumed. In addition, at this time, the user has a problem that the wrong wiring is not noticed. The present invention solves the above problems, and an object thereof is to provide a user with a trouble situation with a display device such as a cathode ray tube without consuming unnecessary electric power and heat.

[0004]

In order to achieve the above-mentioned object, the present invention monitors the power supply voltage supplied to an external unit, and when the voltage is significantly different from a specified value or the load connected is significantly heavy, It has a circuit that electronically stops the power supply. At the same time, this voltage is checked by the microcomputer, and if it is abnormal, a message such as "Please reconnect the BS antenna" is displayed.

[0005]

With the above-described structure, the present invention does not consume unnecessary voltage and heat and can inform the user of incorrect wiring.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.
Will be described with reference to. In the present invention, as shown in FIG. 1, an unstable input voltage is applied to the voltage stabilizing IC 2 and a stable output voltage is supplied to the BS external unit through the switch SW2.

A voltage obtained by dividing the input voltage by the resistors 5 and 6 is applied to the reference voltage terminal of the voltage comparator IC3. On the other hand, a voltage determined by the load connected to the resistor 7 and the switch SW2 is applied to the comparison input terminal. When the voltage of this comparison terminal is lower than the reference voltage, each constant is determined so that the output of the voltage comparator IC3 becomes high level. The output of the voltage comparator IC3 is the voltage stabilizing IC2.
Is connected to the strobe terminal of, and when it is at high level, the switch inside the IC is cut off and the output voltage is not output. Naturally, when the load is in a normal state, the output of the voltage comparator IC3 becomes low level, and the necessary power is supplied.

At the same time, the output voltage is connected to the voltage detection terminal of the tuning microcomputer IC4, and if it is abnormally low, a message such as "Please reconnect the BS antenna" is displayed on the screen of the CRT (cathode ray tube).

[0009]

As is apparent from the above embodiments, according to the present invention, unnecessary power consumption can be prevented when the output voltage is short-circuited.
It does not generate heat, and informs the user of the abnormal condition, making it safe.

[Brief description of drawings]

FIG. 1 is a power supply short-circuit protection circuit according to an embodiment of the present invention.

FIG. 2 Conventional power supply circuit

[Explanation of symbols]

 2 Voltage stabilization IC 3 Voltage comparator IC 4 Tuning microcomputer IC 5 6 7 Resistance SW2 switch

Claims (2)

[Claims] 1. A circuit for safely stopping the power supply when the power supply for the external unit of the satellite broadcast receiving device is short-circuited due to a connection error or the like for the core wire and the ground, and unnecessary power is not needed. 2. A circuit for alerting a user with a display such as a cathode ray tube of a television when a power supply for an external unit of a satellite broadcast receiving device is short-circuited due to a connection error or the like.