JPH058699U - Power alarm circuit - Google Patents

Abstract

(57) [Summary] [PROBLEMS] The present invention relates to a power supply alarm circuit, which issues an alarm when a power supply abnormality inside the device, that is, a power supply voltage drop or a power supply voltage cutoff, or a device input power supply cutoff. Provided is a power supply alarm circuit capable of clearly detecting a failure of the power supply. [Configuration] Step-down regulator 103, resistor 104,
A relay 110, a Zener diode 111, and a resistor 112 are added to a conventional power supply circuit configured by 105, a reference voltage 106, and a comparison amplifier 107.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

  The present invention relates to a power supply alarm circuit, and more particularly to a power supply alarm circuit for a transmission device.

[0002]

[Prior art]

  2. Description of the Related Art Conventionally, this type of power supply alarm circuit has a primary side input terminal 201, as shown in FIG. 202, step-down regulator 203, resistors 204 and 205, and reference voltage 206 Comprised of a comparator amplifier 207, a secondary output terminal 208, and an alarm output terminal 209. In order to supply the primary voltage, which is the DC input power of the equipment, to the inside of the equipment, It is converted to a stable DC secondary voltage by the converter 203, and the secondary output is two resistors. The voltage is divided by 204 and 205, and the voltage is compared with the reference voltage 206 by the comparator 207, It is caused by the overload on the secondary side or the failure of the parts used by obtaining the comparison result. The output voltage drop can be monitored.

[0003]

[Problems to be solved by the device]

  However, in the above-mentioned conventional power supply alarm circuit, the secondary side output voltage decreases. As a result, the reference amplifier will not operate properly and the reference voltage will not be constant. . Therefore, only a certain range of output voltage drop can be detected, and There is a drawback in that the output voltage interruption caused by a failure cannot be detected.

[0004]   The present invention has been made in view of the above-mentioned conventional circumstances, and therefore the object of the present invention is , A new power alarm system that can solve the above-mentioned drawbacks inherent in conventional technology To provide a path.

[0005]

[Means for Solving the Problems]

  In order to achieve the above object, the power supply alarm circuit according to the present invention uses the input power supply of the device. A step-down regulator that converts to a power supply inside the device and the output voltage of this regulator First and second resistors for dividing voltage, a reference voltage, and the first and second resistors And a comparison amplifier for comparing the voltage resulting from the division of the reference voltage with the reference voltage. The relay operated by the output of the amplifier and the input power supply to the comparator amplifier and relay. And a Zener diode that produces a voltage to be supplied.

[0006]

【Example】

  Next, the present invention will be described in detail with reference to the drawings for a preferred embodiment thereof. It

[0007]   FIG. 1 is a circuit configuration diagram showing an embodiment of the present invention. 101 and 102 are on the primary side Input terminal, 103 is a step-down regulator, 104 and 105 are resistors, and 106 is a reference Voltage, 107 is a comparison amplifier, 108 is a secondary side output terminal, 109 is an alarm output, 11 0 is a relay, 111 is a Zener diode, and 112 is a resistor.

[0008]   The primary voltage, which is the DC input power of the equipment, is controlled by the step-down regulator 103. It is converted to a constant DC secondary voltage and supplied to the inside of the device. In addition, from the primary voltage The voltage generated by using the diode 111 is compared with the comparison amplifier 107 and the relay 1. Supply to 10.

[0009]   Normally, if the secondary voltage is a specified value, the secondary voltage is divided by the resistors 104 and 105. The voltage obtained in step 3 is higher than the reference voltage 106, and the output of the comparison amplifier 107 is “Lo”. w ”, which causes a current to flow in the relay 110, and the switch of the relay 110 Becomes "ON", and the alarm output becomes GND level.

[0010]   Now, the secondary voltage drops for some reason, and the resistance division voltage value of the secondary voltage becomes When the voltage becomes lower than the quasi voltage 106, the output of the comparison amplifier 107 becomes “High”. , The current flowing through the relay 110 is stopped, and the relay switch FF ". As a result, the alarm output becomes" OPEN ".

[0011]   Even if the secondary side voltage drops further, if the primary side voltage does not change, The Zener diode 111 supplies the primary voltage to the comparator amplifier 107 and the relay 110. As such, their operation is not affected by the secondary power supply and works normally. To make. Therefore, the alarm circuit operates normally even if the secondary output is cut off. It also issues a disconnection alarm.

[0012]   Next, even if the primary side voltage is cut off, no current will flow in the relay 110. , The relay switch becomes "OFF" and the alarm output becomes "OPEN".

[0013]

[Effect of device]

  As described above, according to the present invention, the alarm circuit uses the primary side power source to output the alarm. Output voltage drop due to secondary side overload or component failure by using relay in the power section It is also possible to detect the output voltage cutoff and also the cutoff of the primary side power supply. The effect that it can be obtained.

[Brief description of drawings]

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

FIG. 2 is a prior art circuit diagram.

[Explanation of symbols]

101, 102 ... Primary side input terminal 103 ... Step-down regulator 104, 105 ... Resistors 106 ... Reference voltage 107 ... Comparative amplifier 108 ... Secondary side output terminal 109 ... Alarm output terminal 110 ... Relay 111 ... Zener diode 112 ... Resistor 201, 202 ... Primary side input terminal 203 ... Step-down regulator 204, 205 ... Resistors 206 ... Reference voltage 207 ... Comparative amplifier 208 ... Secondary side output terminal 209 ... Alarm output terminal

Claims (2)

[Scope of utility model registration request] 1. A step-down regulator for converting an input power source of the device into a power source inside the device, first and second resistors for dividing an output voltage of the regulator, a reference voltage, and the first and second resistors. A comparison amplifier for comparing the voltage resulting from the division of the second resistor with the reference voltage, a relay operated by the output of the comparison amplifier, and a zener diode for producing a voltage supplied from the input power source to the comparison amplifier and the relay. A power supply alarm circuit comprising: 2. The power supply alarm circuit according to claim 1, further comprising a zener diode connected to the input power supply through a third resistor.