3 1/2, 4 1/2 digit intelligent digital voltmeter circuit composed of MAX1492/MAX1494

The 3 1/2, 4 1/2 digit intelligent digital voltmeter circuit composed of MAX1492/MAX1494 is shown in the figure below. It is powered by a single power supply of 2.7~5.25 V, and there is a power decoupling circuit between the analog power input and the digital power input. The power decoupling circuit consists of an inductor LIso ​​and a capacitor. The capacitor at the analog input is used to filter out interference voltage. Resistors RHI and RLow are used to set the threshold voltage V LOWBATT for low voltage indication.