Machine Manufacturing

Analog Devices Introduces RMS-to-DC Converter

August 16, 2011

The AD8436 precision, monolithic, true RMS-to-DC converter ensures accuracy and best-in-class dynamic range.

NORWOOD, MA--(BUSINESS WIRE)-- Analog Devices, Inc. (ADI) unveiled an integrated true RMS-to-DC converter that offers a best-in-class 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 µA 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 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.

AD8436 Precision, Low Power, Monolithic True RMS-to-DC Converter Key Features:

  • Instantly computes true RMS value
    • Fast and constant settling time at all input levels
    • Wide usable dynamic range: 100 µV RMS to 3 VRMS (8.5 V p-p) full-scale
    • Input frequency range: 65 kHz for additional 1 percent error
    • Low power: 300 µA typical at ±2.4 V
    • Accuracy: ±10 µV ±0.5 percent of reading max
  • System-on-a-chip includes FET input buffer with precision gain setting resistors, output buffer
  • Supply range:
    • Dual: ±-2.4 V to ±18 V
    • Single: 4.8 V to 36 V

Availability, Pricing and Complementary Components
Product Availability Temperature Range Price Each Per 1,000 Packaging
AD8436A Full volume production now –40°C to 125°C $4.95 20-lead LFCSP 4 mm x 4 mm
AD8436J Full volume production now 0°C to 70°C $2.95 20-lead LFCSP 4 mm x 4 mm

Complementary components to the AD8436 in low noise, low power, precision applications include the AD7190 24-bit Sigma Delta A/D converter and the ADR3433 micropower, high accuracy voltage references.

About Analog Devices
Innovation, performance, and excellence are the cultural pillars on which Analog Devices has built one of the longest standing, highest growth companies within the technology sector. Acknowledged industry-wide as the world leader in data-conversion and signal-conditioning technologies, Analog Devices serves over 60,000 customers, representing virtually all types of electronic equipment. Analog Devices is headquartered in Norwood, Massachusetts, with design and manufacturing facilities throughout the world. Analog Devices' common stock is listed on the New York Stock Exchange under the ticker "ADI" and is included in the S&P 500 Index.

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