Many system of electronic, expectialy digital system like random access memory and watch digital,
It must give the supply continually to make the operation is running true. if a supply to RAM is break,
all of the information has saving will lost and if the watch digital have the same happen so the time information will be lose too.
The supply failure display that will explained will detect the breaking of supply and will turning on the LED if the supply come in. So, it can to inform the microprocessor if the information that saving in RAM is damage and must enter the new information.
If supply turn on, the input inverting IC will hold 0,6V under positive voltage of supply, it’s caused by D1. With push the button of reset, it will give input the positive voltage to the non inverting IC and make the output IC to high. It will hold the input is high though the reset button is not push. And LED will turn off. If the supply is breaking, all of the voltage is 0. And then supply is back, input IC will make to be potential starting. But capacitor is not content and hold input non inverting is low.
