Analog Devices Inc. AD737JRZ-5

Description
The AD737 is a low-power, precision, monolithic, true rms-to-dc converter. It is laser trimmed to provide a maximum error of ±0.2 mV ± 0.3% of reading with sine wave inputs. It can compute the rms value of both ac and dc input voltages. It can also be operated ac-coupled by adding one external capacitor. The AD737 has no output buffer amplifier, thereby significantly reducing dc offset errors occurring at the output, which makes the device highly compatible with high input impedance ADCs.

Features
Computes true rms value
Low cost, low power
True RMS-to-DC Converter
200 mV full-scale input range (larger inputs with input attenuator)
Direct interfacing with 3% digit CMOS ADCs
High input impedance: 100-Vs
Low input bias current: 25 pA maximum
High accuracy: ±0.2 mV ± 0.3% of reading
RMS conversion with signal crest factors up to 5
Wide power supply range: ±2.5 V to ±16.5 V
Low power: 160 μA maximum supply current
No external trims needed for specified accuracy
A general-purpose, buffered voltage output version also available (AD736)

Applications
Upgrading the performance of non-rms precision rectifiers
Portable multimeters
Battery-powered applications
Measuring variable duty cycle pulses
Measuring triac (phase) controlled sine waves
Computing the average rectified value
Computing the absolute value