Isolated Amplifier with Fixed Gain and Single-Ended Output 

Introduction

This module is a high-voltage isolated voltage monitor based on the ADuM4195-1. It offers excellent linearity, high common-mode noise immunity, low gain error, and minimal temperature drift. These features make it a robust, high-performance solution for industrial applications requiring precise high-voltage sensing. 

The input voltage is sensed through resistor dividers (R3 + R4 and R6 + R7). Since the amplifier operates as a unity-gain device, the output voltage (V-OUT) is proportional to the sensed bus voltage, scaled by the resistor divider ratio. Due to the very high input impedance of the VIN pin, the current through the resistor divider can be kept low without compromising accuracy, resulting in reduced power dissipation. 

The ADuM4195-1 is an isolation amplifier based on Analog Devices’ iCoupler® technology. It features very low offset and gain error, making it ideal for a wide range of isolated voltage sensing applications. 

Unlike optocoupler-based solutions, which can exhibit variations in current transfer ratio over time and instability at high temperatures, the ADuM4195-1 provides a stable transfer function throughout its lifetime and operates reliably over a wide temperature range of −40°C to +125°C. 

The device is certified to provide galvanic isolation up to 5 kV RMS in accordance with UL1577, ensuring high safety and reliability in demanding environments. 

The on-board isolated DC-DC converter supplies power to the high-voltage sensing side, allowing the module to operate from a single DC power supply. A screw terminal is provided for the high-voltage sensing input, while a header connector is available for the DC power input and isolated voltage output. Power indicator LEDs are provided on both the input and isolated sides, making it easy to verify the presence of power during operation. 

With 2M Ohms + 7.8K ohms divider resistor can measure maximum 1000V DC voltage. This range is adjustable 0 to 1KV through divider resistors. Test conducted with 123V DC input, with 123V DC input project provides 0.475V DC output. It is advisable to use 0.1% tolerance divider resistors for accuracy.

Features

• Power Input 5V DC (VDD1: 4.5 V to 5.5 V, VDD2: 4.5 V to 5.5 V) 
• High-impedance input for isolated voltage measurement 
• Fixed gain = 1 
• Low offset error and drift: ±5 mV (maximum) at 25°C and −22µV/°C (typical) 
• Low gain error and drift: ±50.5% (maximum) and ±42 ppm/°C 
• (maximum) 
• ±0.5% (max) and ±42 ppm/°C (maximum) 
• Voltage-supply range 
• Bandwidth: 210 kHz 
• Isolation voltage: 5000 V_rms 
• 4x3mm PCB Mounting Holes 
• PCB Dimensions 48.10 x 24.13mm

Schematic

Connections

• CN1: Pin 1 = VCC, Pin 2 = GND-Output, Pin 3 = V-Output, Pin 4 = GND-Output 
• CN2: Pin 1 = +0 to 1KV Input, Pin 2 = GND-Input 
• D1: Input Side Power LED 
• D2: Output Side LED 

Part List

PCB View

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