RMS-to-DC Converter Ensures Accuracy and Dynamic Range

Analog Devices, Inc. unveiled an integrated true RMS-to-DC converter that offers a 100 µV to 3 V of usable dynamic range and the ability to measure extremely low signal levels with high accuracy and no drop in settling time.

The AD8436 precision monolithic true RMS-to-DC converter features AC conversion accuracy to better than ± 0.5 percent. Uniform settling for widely variant input values enables consistent conversion rates with results displayed promptly for near-zero and high-level AC inputs. The AD8436 is immune to temperature, crest factor and supply voltage variations. Zero DC offset voltages at the converter output simplify calibration. This performance is packed into a compact 4 mm x 4 mm package integrated with a FET input and precision DC buffer amplifiers and consumes only 300 uA of power. The AD8436 is a good choice for remote, portable battery-powered instrumentation, energy and automotive applications where limited board space and outdoor environments are considerations.

The AD8436 system-on-a-chip design computes the precise DC equivalent of the RMS value and provides a level of linearity and accuracy across the entire input range that enables engineers to design systems with 90 dB of dynamic range.

The AD8436 extends the crest-factor to 10 - approximately double the current industry-standard digital solution - with minimal loss of accuracy. It is particularly useful for high transit signals and can be used in designs currently using ADI's low-power, true RMS-to-DC converters such as the AD736 and AD737 with improved performances. The device is laser trimmed and characterized at 300-mV RMS input and comes with dual and single power supplies. The AD8436 is the first RMS-to-DC converter specified to operate in the extended industrial temperature range of -40°C to 125°C. It is also available in a 0°C to 70°C temperature range version.