a FEATURES True RMS-to-DC Conversion Laser-Trimmed to High Accuracy 0.2% max Error (AD536AK) 0.5% max Error (AD536AJ) Wide Response Capability: Computes RMS of AC and DC Signals 450 kHz Bandwidth: V rms > 100 mV 2 MHz Bandwidth: V rms > 1 V Signal Crest Factor of 7 for 1% Error dB Output with 60 dB Range Low Power: 1.2 mA Quiescent Current Single or Dual Supply Operation Monolithic Integrated Circuit –55؇C to +125؇C Operation (AD536AS)
Integrated Circuit, True RMS-to-DC Converter AD536A PIN CONFIGURATIONS AND FUNCTIONAL BLOCK DIAGRAMS TO-116 (D-14) and Q-14 Package
TO-100 (H-10A) Package
The AD536A is a complete monolithic integrated circuit which performs true rms-to-dc conversion. It offers performance which is comparable or superior to that of hybrid or modular units costing much more. The AD536A directly computes the true rms value of any complex input waveform containing ac and dc components. It has a crest factor compensation scheme which allows measurements with 1% error at crest factors up to 7. The wide bandwidth of the device extends the measurement capability to 300 kHz with 3 dB error for signal levels above 100 mV. An important feature of the AD536A not previously available in rms converters is an auxiliary dB output. The logarithm of the rms output signal is brought out to a separate pin to allow the dB conversion, with a useful dynamic range of 60 dB. Using an externally supplied reference current, the 0 dB level can be conveniently set by the user to correspond to any input level from 0.1 to 2 volts rms. The AD536A is laser trimmed at the wafer level for input and output offset, positive and negative waveform symmetry (dc reversal error), and full-scale accuracy at 7 V rms. As a result, no external trims are required to achieve the rated accuracy of the unit. There is full protection for both inputs and outputs. The input circuitry can take overload voltages well beyond the supply levels. Loss of supply voltage with inputs connected will not cause unit failure. The output is short-circuit protected. The AD536A is available in two accuracy grades (J, K) for commercial temperature range (0°C to +70°C) applications, and one grade (S) rated for the –55°C to +125°C extended range. The AD536AK offers a maximum total error of ± 2 mV ± 0.2% of reading, and the AD536AJ and AD536AS have maximum errors of ± 5 mV ± 0.5% of reading. All three versions are available REV. A Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
LCC (E-20A) Package
in either a hermetically sealed 14-pin DIP or 10-pin TO-100 metal can. The AD536AS is also available in a 20-pin hermetically sealed ceramic leadless chip carrier. PRODUCT HIGHLIGHTS
1. The AD536A computes the true root-mean-square level of a complex ac (or ac plus dc) input signal and gives an equivalent dc output level. The true rms value of a waveform is a more useful quantity than the average rectified value since it relates directly to the power of the signal. The rms value of a statistical signal also relates to its standard deviation. 2. The crest factor of a waveform is the ratio of the peak signal swing to the rms value. The crest factor compensation scheme of the AD536A allows measurement of highly complex signals with wide dynamic range. 3. The only external component required to perform measurements to the fully specified accuracy is the capacitor which sets the averaging period. The value of this capacitor determines the low frequency ac accuracy, ripple level and settling time. 4. The AD536A will operate equally well from split supplies or a single supply with total supply levels from 5 to 36 volts. The one milliampere quiescent supply current makes the device well-suited for a wide variety of remote controllers and battery powered instruments. 5. The AD536A directly replaces the AD536 and provides improved bandwidth and temperature drift specifications. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 617/329-4700 Fax: 617/326-8703