AD637SD

The Analog Devices AD637SD is a high-precision, wideband RMS-to-DC converter designed to compute the true RMS value of complex AC or AC plus DC input waveforms, providing an equivalent DC output voltage. This integrated circuit offers performance comparable to discrete and modular techniques in accuracy, bandwidth, and dynamic range.

Key features include a maximum nonlinearity of 0.02% for inputs from 0 V to 2 V rms, with an additional error of only 0.1% for crest factors up to 3. The device boasts a wide bandwidth, operating at 8 MHz for inputs above 1 V rms and 600 kHz for inputs as low as 100 mV rms. It can compute true RMS, mean square, or absolute value, and provides a direct dB output with a 60 dB range.

The AD637SD is suitable for applications requiring precise power measurement, as the true RMS value directly relates to signal power. Its superior crest factor compensation allows for accurate measurements of signals with crest factors up to 10 with less than 1% additional error. The device operates with supply voltages from ±3V to ±18V and has a typical quiescent current of 2.2 mA, which can be reduced to 350 µA in power-down mode.

Packaged in a 14-CDIP (0.300", 7.62mm) through-hole configuration, the AD637SD is designed for ease of integration into existing circuit designs. The chip select feature allows for analog three-state operation, enabling multiple AD637s to be connected for wideband true RMS multiplexer applications.