MCP3905A-I/SS

Description

Microchip IC that works as an active power meter in circuits connected to the single-phase mains distribution line. It uses two 16-bit Delta-Sigma A/D converters to read the voltage across a series sense resistor (used to work out the current drawn) and at the input terminals; the chip uses the drop read across the resistor to work out the apparent power drawn by the load, and the one sensed across the incoming line to make a phase comparison. Since it was designed for building electricity meters, it reports instantaneous consumption to the outside world through three outputs that deliver pulses whose frequency is directly proportional to the draw. The current input is so sensitive that it can work with a series resistor of just 0.2 milliohm, and can therefore detect voltages of only 0.2 mV per ampere drawn.