Circuit Project Electronic

This simple TTL power supply monitor circuit monitors the 5-volt level TTL power line and gives a signal whether the supply voltage is outside or within the necessary range or “window”. The heart of the power supply monitor is a low-current integrated window comparator. The center of this window is set at 2.5 volt +/- 0.005 volt by the bandgap reference diode D1 which is connected to pin 2 of LTC1042. The width of this window must be 20% (+/- 10%) of the reference voltage.

The reference voltage is reduced by 25% through R4 and R5 and fed to pin 5 of the IC. The monitored voltage is then fed to pin 2 so that the green LED D2 will light up when the voltage is within the desired range. Otherwise, the red LED D3 will light up signalling that
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