AD737AQ

Overview

The AD737AQ is a low power, precision, monolithic true RMS-to-DC converter manufactured by Analog Devices. It computes the true root-mean-square value of an input signal and provides a corresponding DC output voltage. The device features a wide power supply range from ±2.5 V to ±16.5 V and maintains high accuracy with a maximum error of ±0.2 mV plus 0.3% of reading for sine wave inputs. It supports signals with crest factors up to 5 and offers a 200 mV full-scale input range. The component operates within a temperature range of -40 °C to +85 °C and utilizes a 14-pin CDIP package.

Feature Summary

• Computes true RMS values directly without external trimming
• High input impedance with low bias current for minimal loading
• Capable of handling variable duty cycle pulses and phase-controlled sine waves
• Provides direct interfacing capability with standard CMOS ADCs

Applications

• Upgrading performance in non-RMS precision rectifier circuits
• Direct interfacing with 3½ digit CMOS analog-to-digital converters
• Measurement of triac phase-controlled sine wave signals
• Analysis of variable duty cycle pulse waveforms

Procurement Notes

Verify the specific suffix 'AQ' corresponds to the commercial temperature grade (-40 °C to +85 °C) and ceramic dual in-line package (CDIP). Confirm that the datasheet revision matches the required electrical tolerances, specifically the ±0.2 mV offset and 0.3% gain accuracy specifications. Ensure the ordering information aligns with the 14-pin configuration and single-chip architecture defined in the official Analog Devices documentation.

Selection Notes

Select this component when precise RMS conversion is required for complex waveforms including pulses and phase-controlled signals. It is suitable for applications demanding high input impedance and low power consumption. Consider the negative-going output characteristic and verify compatibility with downstream circuitry. The device eliminates the need for external calibration trims, simplifying design compared to discrete solutions.

Part Context

The AD737 series represents a family of precision analog computing devices designed for accurate signal measurement. As a monolithic solution, it integrates the necessary circuitry for RMS computation on a single chip. This approach reduces physical size and cost while improving reliability over traditional discrete implementations. The AQ variant specifies the industrial temperature range and packaging style for robust operation.

Replacement Considerations

The AD736 serves as a functional alternative with a positive-going output characteristic. Both devices share the same basic internal architecture and performance metrics. Selection between them depends primarily on the polarity requirements of the subsequent stage in the signal chain.