RMS-to-DC convecter brings new architecture to basic meters
( 01 Apr 2002 )
Bill Schweber
Measurement of the true root mean square (rms) value of a waveform is essential in many test and measurement applications. The LT1966 converter IC from Linear Technology uses a DS-based conversion technique, rather than a conventional log/antilog approach, to provide high performance at low cost for waveforms to 1 kHz, with crest factors of up to 5. Untrimmed total error is less than 0.25% from 50 Hz to 1 kHz, and linearity is 0.02% for inputs from 50 to 350 mV. Due to its internal design, the LT1966 operates from single or dual supplies and low voltage (+2.5 to 5V, or ±5V) while drawing just 170 µA. The 8-pin MSOP device accepts single-ended or differential signals with rail-to-rail input and output, and requires just a single external capacitor for operation. The device costs US$2.95 (1000).
