JP2000188826A - Power supply circuit - Google Patents

Abstract

(57) [Summary] In a power supply circuit of an electronic device to which power is supplied from a DC power supply, it is possible to prevent the destruction of the electronic device when electrodes are erroneously reversely connected or a high voltage is applied. Provide a power supply circuit. SOLUTION: In an electronic circuit of an electronic device to which power is supplied from a DC power supply, a Zener diode is used as a protection diode connected between a positive electrode and a negative electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit used, for example, for a radio.

[0002]

2. Description of the Related Art An example of a conventional power supply circuit will be described with reference to FIG. As shown in FIG. 2, a power supply circuit of an electronic device using a DC power supply includes a positive terminal 1, a fuse 2, a reverse connection protection diode 6, and a negative terminal 4 and supplies power to the electronic device 5. The reverse connection protection diode 6 has a cathode connected to the positive electrode and an anode connected to the negative electrode. Usually, the positive power supply is connected to the positive terminal 1 and the negative power supply is connected to the negative terminal 4. The power supply
The current is applied to the positive electrode terminal 1, supplied to the electronic device 5 through the fuse 2, and a current flows to the negative electrode terminal 4. Here, if the positive power supply is erroneously connected to the negative terminal 4 and the negative power supply is connected to the positive terminal 1, a current flows through the reverse connection protection diode 6 having the cathode connected to the cathode and the anode connected to the negative side, cutting the fuse 2, The electronic device 5 is prevented from being destroyed.

[0003]

However, in the above-mentioned prior art, although destruction of equipment due to reverse connection of the power supply can be prevented, for example, a car battery used for a power supply of a vehicle-mounted radio device includes: Since there are two types, 12 volt and 24 volt, 1
If a 2-volt radio is incorrectly connected, the radio may be destroyed. An object of the present invention is to eliminate these drawbacks and to provide a power supply circuit capable of reverse connection protection and high-voltage protection.

[0004]

The present invention achieves the above object by using a Zener diode as a protection diode. As a result, at the time of reverse connection, as in the prior art, a current flows through the diode to cut the fuse, prevent destruction of the device, and set the voltage value of the Zener diode to a predetermined value so that the voltage exceeds the set voltage. Even when the voltage is applied, a current flows through the diode to cut the fuse and prevent destruction of the device. Therefore, a power supply circuit with reverse connection and high voltage protection can be realized.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. As shown in FIG. 1, a power supply circuit of an electronic device using a DC power supply includes a positive terminal 1, a fuse 2,
It is composed of a reverse connection using a Zener diode, a high voltage protection diode 3 and a negative terminal 4, and supplies power to the electronic device 5. The reverse connection, high voltage protection diode 3 is
The cathode is connected to the positive electrode side, and the anode is connected to the negative electrode side. Normally, a positive power supply is connected to the positive terminal 1 and a negative power supply is connected to the negative terminal 4. Power is applied to the positive terminal 1, supplied to the electronic device 5 through the fuse 2, and a current flows to the negative terminal 4. When the positive power supply is erroneously connected to the negative terminal 4 and the negative power supply is erroneously connected to the positive terminal 1, a reverse connection in which the cathode is connected to the negative electrode and the anode is connected to the negative electrode 4 To prevent equipment destruction. In addition, when a zener diode of, for example, 20 volts is used for the reverse connection and high voltage protection diode 5, 1
Even when a 2 volt wireless device is erroneously connected to a 24 volt battery, a current flows through the Zener diode, cutting the fuse 2 and preventing destruction of the device.

[0006]

According to the present invention, when a reverse connection and a high voltage are erroneously applied, the fuse is cut to prevent the destruction of the equipment, and the power supply capable of performing the reverse connection and the high voltage protection. A circuit can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a conventional power supply circuit.

[Explanation of symbols]

1: Positive terminal, 2: Fuse,
3: Reverse connection, high voltage protection diode (Zener diode), 4: Negative terminal, 5: Electronic equipment, 6: Reverse connection protection diode.

Claims (1)

[Claims] 1. A power supply circuit for an electronic device to which power is supplied from a DC power supply, wherein a protection diode connected between a positive electrode and a negative electrode of the power supply circuit comprises a zener diode.