AD636

a FEATURES True RMS-to-DC Conversion 200 mV Full Scale Laser-Trimmed to High Accuracy 0.5% Max Error (AD636K) 1.0% Max Error (AD636J) Wide Response Capability: Computes RMS of AC and DC Signals 1 MHz –3 dB Bandwidth: V RMS >100 mV Signal Crest Factor of 6 for 0.5% Error dB Output with 50 dB Range Low Power: 800 ␮ A Quiescent Current Single or Dual Supply Operation Monolithic Integrated Circuit Low Cost Available in Chip Form PRODUCT DESCRIPTION VIN 1 NC 2 –VS 3 CAV 4 dB 5 BUF OUT 6 BUF IN 7 Low Level, True RMS-to-DC Converter AD636 PIN CONNECTIONS & FUNCTIONAL BLOCK DIAGRAM IOUT ABSOLUTE VALUE 14 +VS 13 NC RL 10k⍀ + CURRENT MIRROR BUF IN – AD636 SQUARER DIVIDER COMMON 12 NC 11 NC AD636 BUF BUF OUT 10k⍀ CURRENT MIRROR + BUF – 10k⍀ 10k⍀ 10 COMMON 9 8 +VS SQUARER DIVIDER ABSOLUTE VALUE dB RL IOUT VIN CAV –VS NC = NO CONNECT The AD636 is a low power monolithic IC which performs true rms-to-dc conversion on low level signals. It offers performance which is comparable or superior to that of hybrid and modular converters costing much more. The AD636 is specified for a signal range of 0 mV to 200 mV rms. Crest factors up to 6 can be accommodated with less than 0.5% additional error, allowing accurate measurement of complex input waveforms. The low power supply current requirement of the AD636, typically 800 µA, allows it to be used in battery-powered portable instruments. A wide range of power supplies can be used, from ± 2.5 V to ± 16.5 V or a single +5 V to +24 V ...