AD637BR

The AD637BR is one member of the AD637 series.The AD637 is a complete high accuracy monolithic rms-to-do converter that computes the true rms value of any complex waveform. It offers performance that is unprecedented in integrated circuit rms-to-do converters and comparable to discrete and modular techniques in accuracy, bandwidth and dynamic range.A crest factor compensation scheme in the AD637 permits measurements of signals with crest factors of up to 10 with less than 1%additional error. The circuit's wide bandwidth permits the measurement of signals up to 600 kHz with inputs of 200 mV rms and up to 8 MHz when the input levels are above 1 V rms.

Features of the AD637BR are:(1)high accuracy:0.02% max nonlinearity, 0 V to 2 V RMS input,0.10% additional error to crest factor of 3; (2)wide bandwidth:8 MHz at 2 V RMS input,600 kHz at 100 mV RMS; (3)computes:true rms,square,mean square,absolute value; (4)dB output 160 dB range); (5)chip select-power down feature allows:analog "3-state" operation,quiescent current reduction from 2.2 mA to 350 p,A; (6)side-brazed DIP, low cost cerdip and SOIC.

The absolute maximum ratings of the AD637BR can be summarized as:(1)lead temperature range (soldering 10 sets):+300;(2)storage temperature range:-65 to 150;(3)rated operating temperature range:-40 to 85;(4)ESD rating:500V;(5)supply voltage:±18V;(6)internal quiescent power dissipation:108mW.A chip select connection on the AD637 permits the user to decrease the supply current from 2.2 mA to 350A during periods when the rms function is not in use. This feature facilitates the addition of precision rms measurement to remote or hand-held applications where minimum power consumption is critical.In addition when the AD637 is powered down the output goes to a high impedance state.This allows several AD637s to be tied together to form a wide-band true rms multiplexer.The AD637 is laser wafer trimmed to achieve rated performance without external trimming.The only external component required is a capacitor which sets the averaging time period.The value of this capacitor also determines low frequency accuracy, ripple level and settling time.