KR960010917B1 - Circuit to decide a power on/off - Google Patents

Abstract

a rectifying circuit(110) rectifying a main power source to a voltage; a power on/off-sensing circuit(120) sensing the power on/off state of the main power source in response to the voltage supplied from the rectifying circuit(110); a comparing circuit(130) generating a logic "1" or "0" by comparing the voltage from the power on/off-sensing circuit(120) with a reference voltage; and a power on/off state-generating circuit(140) generating logic "1" or "0" in response to the logic value from the comparing circuit(130).

Description

Power On and Off Discrimination Circuit

Is a block diagram illustrating a power on and off discrimination circuit in accordance with the present invention;

* Explanation of symbols for main parts of the drawings

110: rectifier circuit 120: power on and off detection circuit

130: comparison circuit 140: power on and off output generation circuit

150: voltage divider circuit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for determining a voltage state of a main power supply, and in particular, a power on and off discrimination circuit for detecting in advance that the main power is turned off or the power becomes unstable in order to safely back up working data. It is about.

Data Song. In a general apparatus having a reception function, when sudden power failure or power instability occurs, various data worked in the meantime are completely or partially lost. That is, the preceding device does not have any device for compensating when the main power is suddenly turned off or unstable or backing up so that there is no loss of data in the fraud. Therefore, there has been a demand for the development of a device for determining a device having a backup memory when the main power is off or unstable so that the data can be safely backed up before the device is completely turned off or unstable.

Accordingly, an object of the present invention is to provide a power on and off discrimination circuit that detects that the main power is turned off or the power becomes unstable so that the data which has been worked up can be safely backed up.

According to the present invention, a rectifier circuit is provided at a predetermined voltage by inputting a main power source; A power on and off detection circuit for sensing the on and off states of the main power in response to the voltage provided from the rectifier circuit; A comparison circuit for generating a logic one or zero level by comparing a voltage provided from the power on and off sensing circuits with a preset reference voltage; And a power-on and off-state generating circuit for generating a logic 0 or 1 level in response to a predetermined logic value provided by said comparing circuit.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention;

Figure is a circuit diagram showing a preferred embodiment of the power on and off discrimination circuit according to the present invention, this circuit is rectified circuit 110 to rectify to a predetermined voltage when AC power is input through an AC power line A power on and off detection circuit for inputting a predetermined voltage output from the rectifier circuit 110 to divide the voltage and a power supply on and off by inputting a predetermined voltage from the voltage dividing circuit 150. 120. In addition, as shown, the power on and off discrimination circuit compares the voltage output from the power on and off sensing circuit 120 with a predetermined reference voltage and outputs a logic 1 or 0 and a comparison circuit 130. Power on and off output generation circuit 140 for generating an output value for a predetermined power on and off in response to a logic value output from

Referring to the series of operations of the present invention configured as described above are as follows.

First, when AC power, that is, main power is input or normal, the rectifier circuit 110 rectifies it when the voltage input through the AC power line is, for example, an AC voltage of about 90 to 132V, about 10V to 17V. For the sake of brevity, the output thereof is coupled to the input line of the voltage dividing circuit 150 and may be spherical with a known rectifying bridge diode (not shown). The division circuit 150 is coupled to the output line of the rectifier circuit 110 and inputs a rectified predetermined voltage to divide the desired predetermined voltage, that is, about 5.67 V to 8.32 V in the embodiment of the present invention. Its output is coupled to the input line of the power on and off sense circuit 120 and can be implemented with known resistors (not shown) or the like.

In addition, the power on and off detection circuit 120 is to detect the power on and off state, when a predetermined voltage is input from the voltage distribution circuit 150, a predetermined current flows to the optical sensor diode shown, Therefore, the OV is almost applied to the collector terminal of the phototransmitter transistor TR, and this value is coupled to one input line of the comparison circuit 130. The comparison circuit 130 is coupled to the output lines of the power on and off detection circuit 130, and at the same time, the reference voltage Vref (Vref is set to about 2V in the embodiment of the present invention) preset to the other input line. Coupled to output a final logic one level, the output of which is coupled to the input lines of the power on and off output generation circuit 140.

The power on and off output generation circuit 140 receives the signal output from the comparison circuit 130 and generates an output signal for the on and off states of the main power supply, as shown in the P-type TR (Q141). And a resistor R142. If a logic 1 level is applied to the bass stage of the P-type TR Q141, the TR Q141 is turned off so that a logic 1 level is applied to the emitter stage, and the system receiving such a power source operates normally.

Then, when the main power is off or unstable, voltage is not applied to the output terminals of the rectifier circuit 110 and the voltage dividing circuit 150 so that the optical sensor diodes of the power on and off detection circuit 120 are not operated. Accordingly, a voltage greater than a reference value of the comparison circuit 130 is applied to the collector terminal of the light receiving transistor, and the comparison circuit 130 outputs a logic zero level. As a result, the P-type TR (Q141) of the power-on and off-output generator circuit 140 is turned on, so that the emitter output voltage of the TR (Q141) becomes logic 0 sooner than the power source (Vcc).

In an exemplary embodiment of the present invention, the main power on and off signals are generated before the sub power supply Vcc is turned off. In this case, the power supply is turned off after the signal indicating that the main power is off is maintained for about 2 msec or more. By doing so, you can back up the data you have worked on in the memory and keep the data safe.

As described above, according to the present invention, when the main power is turned off or unstable, the main power is sensed to be turned off, and the data is safely protected by backing up the data that has been worked for a predetermined time before the sub power is completely turned off to the predetermined memory device. Make it possible.

Claims (3)

A rectifier circuit inputted by a main power supply and rectified to a predetermined voltage; A power on and off detection circuit for sensing the on and off states of the main power in response to the voltage provided from the rectifier circuit; A comparison circuit for generating a logic 1 or 0 level by comparing the voltage provided from the power on and off sensing circuits with a preset reference voltage; And a power on and off state generation circuit for generating a logic 0 or 1 level in response to a predetermined logic value provided by said comparison circuit. The circuit of claim 1, wherein the power on and off discrimination circuit further includes a voltage divider circuit coupled to an output line of the rectifier circuit to divide the output voltage from the rectifier circuit to provide the power on and off sensing circuit input line. Power on and off discrimination circuit. 3. The power on and off discrimination circuit according to claim 2, wherein the power on and off detection circuit comprises an optical sensor element.