A multirate electricity meter needs to know the day and time. During each day, it accumulates energy usage into one of several energy accumulators for multiple tariff billing periods that can change through the day, and from day to day. Consequently, maintaining an accurate account of time is a critical task for the meter.
The MAXQ3120’s electricity meter reference design provides two methods for keeping accurate time: an internal time-of-day clock built into the MAXQ3120 microcontroller, or a fully compensated, external clock.

In this application note, an electricity-meter reference design uses the MAXQ3120 microcontroller to maintain an accurate account of time and electricity usage over multiple tariff billing periods.