AD636

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 mA Quiescent Current
Single or Dual Supply Operation
Monolithic Integrated Circuit
Low Cost
Available in Chip Form




Pinout








Specifications

Supply Voltage
Dual Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±16.5 V
Single Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +24 V
Internal PowerDissipation2
. . . . . . . . . . . . . . . . . . . .500 mW
Maximum Input Voltage . . . . . . . . . . . . . . . . . . . . ±12 V Peak
Storage Temperature Range N, R . . . . . . . .55°C to +150°C
Operating Temperature Range
AD636J/K . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C
Lead Temperature Range (Soldering 60 sec) . . . . . . +300°C
ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1000 V






Description

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 supply. The input and output terminals are fully protected; the input signal can exceed the power supply with no damage to the device (allowing the presence of input signals in the absence of supply voltage) and the output buffer amplifier is short-circuit protected. The AD636 includes an auxiliary dB output. This signal is derived from an internal circuit point which represents the loga- rithm of the rms output. The 0 dB reference level is set by an externally supplied current and can be selected by the user to correspond to any input level from 0 dBm (774.6 mV) to 20 dBm (77.46 mV). Frequency response ranges from 1.2 MHz at a 0 dBm level to over 10 kHz at 50 dBm.