True RMS-to-DC Converter 

Introduction

This is a low-cost, low-power True RMS-to-DC converter designed to provide accurate RMS measurements over a wide range of input waveforms. It can accurately measure complex signals, including variable-duty-cycle pulses and TRIAC (phase)-controlled sine waves. 

The converter is built around the AD736 True RMS-to-DC converter IC, providing high accuracy while maintaining low power consumption and a compact circuit design. Its low cost and small size make it an excellent solution for upgrading the performance of conventional non-RMS precision rectifier circuits in a wide range of measurement and instrumentation applications. 

Compared with conventional rectifier-based circuits, the AD736-based design offers higher accuracy at an equal or lower overall cost. The AD736 provides a 1% reading accuracy bandwidth exceeding 10 kHz for input amplitudes ranging from 20 mV RMS to 200 mV RMS, while consuming only approximately 1 mW of power (Only Chip), LED draw 10mA.  

Features

• Power Supply +/-5V DC (Dual 5V DC) 
• Input Voltage Range 200mV, 2V, 20V, 200V 
• Output 20 to 200mV DC 
• Input 20mV to 200mV  
• True RMS-to-DC conversion 
• Low cost and low power consumption 
• High measurement accuracy 
• Supports complex and non-sinusoidal waveforms 
• Measures variable-duty-cycle pulse signals 
• Suitable for TRIAC phase-controlled sine waves 
• 1% reading accuracy bandwidth exceeding 10 kHz* 
• Input range: 20 mV RMS to 200 mV RMS* 
• Compact design 
• Ideal for replacing or upgrading precision rectifier circuits 
• PCB Mounting Holes 4x4mm
• PCB Dimensions 43.18 x 31.75mm

Schematic

Connections

• CN1: Pin 1 = AC Signal Input, Pin 2 = GND 
• CN2: Pin 1 = +5V DC, Pin 2 = GND, Pin 3 = -5V DC, Pin 4 = DC Voltage Output, Pin 5 = GND 
• Jumpers: J1 = 200mV, J2 = 2V, J 3 = 20V, J4 = 200V (Input Voltage Range Selection)  
• D3: Power LED 

Part List

PCB View

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