Isolated Analog Input Module v2
This Isolated Analog Input module is designed for industrial applications, optically isolating 0−5V sensor signals to output 0−3.3V for microcontrollers. It uses a linear optocoupler (3750V isolation) and requires two separate 5V supplies. A simple resistor change allows it to accept 0−10V inputs.
This Isolated Analog Input module is designed for interfacing a wide range of analog signals from sensors and field devices. It is ideal for process control, factory automation, and various industrial applications.
The module simplifies the task of connecting analog voltages or sensors to Arduino boards or other microcontrollers while ensuring complete optical isolation. It requires two separate 5V DC power supplies – one for the input side and one for the output side.
By default, the module accepts a 0–5V analog input and provides an optically isolated 0–3.3V output.
To use the module, connect your sensor or analog voltage to the input side, and wire the output to an analog pin of an Arduino or the ADC input of any microcontroller.
The design is based on an optically isolated linear optocoupler with an isolation voltage rating of 3750V. The IC2 MCP601 operates as a closed-loop servomechanism, sensing the photodiode current and driving the optocoupler’s LED. IC1 is the linear optocoupler itself, while IC3 MCP601 serves as a signal conditioner for the phototransistor output. A D1 power LED indicates the input-side power status.
The LOC110 Single Linear Optocoupler features an infrared LED optically coupled with two photodiodes. One feedback (input) photodiode is used to generate a control signal that provides a servomechanism to the LED drive current, thus compensating for the LED’s nonlinear time and temperature characteristics. The other (output) photodiode provides an output signal that is linear to the servo LED current. The IC features wide bandwidth, high input-to-output isolation, and excellent servo linearity.
Features
- Supply input Side 5V DC
- Supply Output Side 5V DC
- Input Voltage Range 0-5V DC
- Output 0-3.3V DC
- PCB Dimensions: 30.48 x 12.86 mm
Connections
- Pin 1 = VCC 5V DC, Pin 2 = Analog Input 0-5V DC, Pin 3 = GND Input Side
- Pin 1 = VCC2 5V DC, Pin 2 = Analog Output 0-3.3V DC, Pin 3 GND Output Side
- D1 = Power LED Input Side
Schematic
Parts List
| NO. | QNTY. | REF. | DESC. | MANUFACTURER | SUPPLIER | SUPPLIER PART NO |
|---|---|---|---|---|---|---|
| 1 | 2 | CN1,CN2 | 3 PIN MALE HEADER PITCH 2.54MM | WURTH | DIGIKEY | 732-5316-ND |
| 2 | 2 | C1,C4 | 10uF/16V CERAMIC SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
| 3 | 2 | C2,C3 | 0.1uF/100nF/50V CERAMIC SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
| 4 | 1 | C5 | 100PF/16V CERAMIC SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
| 5 | 1 | D1 | LED RED SMD SIZE 0805 | OSRAM | DIGIKEY | 475-1278-1-ND |
| 6 | 1 | R1 | 1K 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
| 7 | 1 | R2 | 10K 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
| 8 | 1 | R3 | 499E 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
| 9 | 1 | R4 | 4K7 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
| 10 | 1 | R5 | 20K 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
| 11 | 2 | R6,R7 | 100K 1% SMD SIZE 0805 | YAGEO/MURATA | DIGIKEY | |
| 12 | 1 | R8 | DNP | |||
| 13 | 1 | U1 | LOC110 DIP8 | LITTELFUSE INC | DIGIKEY | 5656-LOC110-ND |
| 14 | 2 | U2,U3 | MCP601 SOT23 | MICROCHIP | DIGIKEY | MCP601T-I/OTCT-ND |
Connections
Gerber View
Photos
