AD637JD

Overview

The AD637JD is a high-precision monolithic RMS-to-DC converter manufactured by Analog Devices Inc. It computes the true RMS value of complex waveforms with 0.02% maximum nonlinearity for inputs between 0 V and 2 V rms. The device supports a wide bandwidth, reaching 8 MHz at 2 V rms input and 600 kHz at 100 mV rms. It features crest factor compensation allowing measurements up to a crest factor of 10 with less than 1% additional error. The component operates on dual supplies ranging from ±3 V to ±15 V and is housed in a 14-pin DIP package.

Feature Summary

• Computes true RMS, square, mean square, absolute value, and dB output (60 dB range).
• Includes chip select/power-down feature enabling analog three-state operation and reduced quiescent current.
• Provides high accuracy with minimal additional error for signals with high crest factors.

Applications

• Precision AC voltage measurement systems
• Audio signal analysis and processing
• Vibration monitoring and control instrumentation

Procurement Notes

Verify the specific suffix 'JD' against the manufacturer's official datasheet to confirm it denotes the standard commercial grade in a side-brazed DIP package. Ensure the ordering code matches the required temperature range and pin configuration. Cross-reference the part number with Analog Devices documentation to distinguish it from other variants like AD637A or AD637AQ which may have different performance specifications.

Selection Notes

Select this component when high accuracy and wide bandwidth are required for RMS conversion. It is suitable for applications involving complex waveforms where crest factor errors must be minimized. Consider the power-down capability if low standby current is necessary. Verify that the input signal levels fall within the specified dynamic range for the desired bandwidth performance.

Part Context

The AD637 series represents a family of high-performance RMS-to-DC converters designed for precision measurement applications. The AD637JD variant specifically utilizes a ceramic dual in-line package (CDIP) construction. This packaging style offers robustness and hermetic sealing characteristics compared to plastic packages, making it suitable for demanding industrial environments.

Replacement Considerations

The AD637A is a higher-grade version of the same functional circuit. The AD637AQ is an aerospace/qualified variant. Direct pin-compatible replacements from other manufacturers, such as the LTC1966 or LTC1968, require verification of bandwidth and linearity specifications to ensure they meet the original design requirements.