Analog Devices Introduces True RMS-to-DC Converter
Analog Devices, Inc. (ADI) unveiled an integrated true RMS-to-DC converter that offers a best-in-class 100µV to 3V 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 x 4mm package integrated with a FET input and precision dc buffer amplifiers and consumes only 300µA 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.
RMS (root mean square) is a fundamental measurement of the magnitude of an ac and dc signal and is a better measure of the power in a signal than simple averaging. RMS-to-DC converters are used in applications where precise, low power measurement of ac-dc signals is the prime objective. 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 300mV 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 to 125°C. It is also available in a 0 to 70°C temperature range version.
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