AD536AJD Electronic IC Chips Integrated Circuit True RMS-to-DC Converter

Integrated Circuit True RMS-to-DC Converter

AD536A

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 M

onolithic Integrated Circuit

–55℃ to +125℃ Operation (AD536AS)

PRODUCT DESCRIPTION

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 unit accuracy.

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 in either a hermetically sealed 14-lead DIP or 10-pin TO-100 metal can. The AD536AS is also available in a 20-leadless hermetically sealed ceramic 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.

PIN CONFIGURATIONS AND FUNCTIONAL BLOCK DIAGRAMS

ABSOLUTE MAXIMUM RATINGS¹

Supply Voltage

   Dual Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±18 V

   Single Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +36 V

Internal Power Dissipation² . . . . . . . . . . . . . . . . . . . . 500 mW

Maximum Input Voltage . . . . . . . . . . . . . . . . . . . . ±25 V Peak

Buffer Maximum Input Voltage . . . . . . . . . . . . . . . . . . . . . ±VS

Maximum Input Voltage . . . . . . . . . . . . . . . . . . . . ±25 V Peak

Storage Temperature Range . . . . . . . . . . . . –55°C to +150°C

Operating Temperature Range

    AD536AJ/K . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C

    AD536AS . . . . . . . . . . . . . . . . . . . . . . . . –55°C to +125°C

Lead Temperature Range

    (Soldering 60 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . +300°C

ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000 V

NOTES

1 Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

2 10-Pin Header: θ_JA = 150°C/W; 20-Leadless LCC: θ_JA = 95°C/W; 14-Lead Size Brazed Ceramic DIP: θ_JA = 95°C/W.

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