Description

The AD737JN is a low power, precision, monolithic true rms-to-dc converter belonging to the RMS-to-DC Converters product category. It is laser trimmed to provide a maximum error of ±0.2 mV ±0.3% of reading with sine-wave inputs. Moreover, it maintains high accuracy while measuring a wide range of input waveforms, including variable duty cycle pulses and triac (phase) controlled sine waves. The small physical size and low cost make it a suitable component for upgrading the performance of non-rms “precision rectifiers” in many applications. Compared to these circuits, the AD737JN offers higher accuracy at equal or lower cost.

Specifications and features

• Computes True RMS Value
• Average Rectified Value
• Absolute Value
• Provides 200 mV Full-Scale Input Range (Larger Inputs with Input Attenuator)
• Direct Interfacing with 3 1/2 Digit CMOS A/D Converters
• High Input Impedance of 1012 V
• Low Input Bias Current: 25 pA max
• High Accuracy: 60.2 mV 60.3% of Reading
• RMS Conversion with Signal Crest Factors Up to 5
• Wide Power Supply Range: +2.8 V, –3.2 V to 616.5 V
• Low Power: 160 mA max Supply Current
• No External Trims Needed for Specified Accuracy
• AD736—A General Purpose, Buffered Voltage Output Version Also Available

Application Scenarios

The AD737JN true rms-to-dc converter can be used in various applications that need precision measurements of the input waveforms, including:

• High-precision AC measurement instruments
• AC measurement systems for power electronics
• Industrial automation
• Medical equipment

Comparison

• High accuracy in measuring a wide range of input waveforms
• Small physical size, making it suitable for applications with limited space
• No external trims are needed for specified accuracy
• Low cost compared to other precision rectifiers

• The maximum error is ±0.2 mV ±0.3% of reading with sine-wave inputs
• The RMS-to-DC conversion has signal crest factors up to 5
• The power supply voltage range is limited to +2.8 V to –3.2 V to 616.5 V