A programmable power metering chip

A programmable power metering chip that measures watt-hours, VAR-hours, and VA-hours is described. New techniques are employed to multiplex analog and digital hardware and achieve significant power and die size efficiences. The chip consists of three time-multiplexed /spl Sigma/-/spl Delta/ A/D (analog-to-digital) converters and an 8-bit programmable DSP (digital signal processor). It is fabricated in 1.5-/spl mu/m CMOS technology with a 5.0 mm/spl times/5.5 mm die and consumes less than 75 mW with single 5-V supply.