# 8 Channel I2C Relay output Module

8 channel I2C relay output module based on the MCP23008

- **Seller:** [EA Control Tech](https://lectronz.com/stores/eacontroltech), Oakland, California, United States
- **Price:** $35.00 (USD, before shipping and taxes)
- **Availability:** In stock
- **Categories:** Application, Equipment, Technology
- **Country of origin:** United States
- **Product page:** https://lectronz.com/products/-8-channel-i2c-relay-output-module

## Links

- [Documentation](https://eacontroltech.com/8_DO_MCP23008.pdf)
- [Schematics](https://eacontroltech.com/8_DO_MCP23008_Schematic.pdf)

## Images

![8 Channel I2C Relay output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MTgsInB1ciI6ImJsb2JfaWQifX0=--673b4efc41b3c3a88bd18d74714bfc75af7c5166/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T01-04-10.643Z-8_DO_MCP23008_7..jpeg)
![8 Channel I2C Relay output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MTksInB1ciI6ImJsb2JfaWQifX0=--6da08caaba94811a3aff805f130164065246a9d2/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T01_04_10.643Z-8_DO_MCP23008_2..jpeg)
![8 Channel I2C Relay output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MjAsInB1ciI6ImJsb2JfaWQifX0=--99242270fbf7a156be40b544f9f20080ca2c6b0f/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T01_04_10.643Z-8_DO_MCP23008_1..jpeg)
![8 Channel I2C Relay output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MjEsInB1ciI6ImJsb2JfaWQifX0=--103817f9035292d221379e9193eb00fb603aa5cf/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T01-04-10.643Z-8_DO_MCP23008_3..jpeg)
![8 Channel I2C Relay output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MjIsInB1ciI6ImJsb2JfaWQifX0=--ece551b3fd2b20d63cb3daf958e889a3681b8c26/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T01-04-10.643Z-8_DO_MCP23008_4..jpeg)
![8 Channel I2C Relay output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MjMsInB1ciI6ImJsb2JfaWQifX0=--e85ff506d21bd34d494811d4929873ac093a3b62/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T01-04-10.643Z-8_DO_MCP23008_8..jpeg)
![8 Channel I2C Relay output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MjQsInB1ciI6ImJsb2JfaWQifX0=--ac1160ae9b01d21806645c59a9a1f1326371b1f3/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGciLCJyZXNpemVfdG9fbGltaXQiOls5NjAsNjQwXSwic2F2ZXIiOnsic3RyaXAiOnRydWV9fSwicHVyIjoidmFyaWF0aW9uIn19--970c165836a83091725a1a0fd4f37ce9408da1bf/2026-04-29T01-04-10.643Z-8_DO_MCP23008_6.jpg)
![8 Channel I2C Relay output Module](https://lectronz-images.b-cdn.net/lectronz/active_storage/representations/proxy/eyJfcmFpbHMiOnsiZGF0YSI6Njg5MjUsInB1ciI6ImJsb2JfaWQifX0=--ddeae4f4c11e0a38c67772067fe5ce0a5a7f6b75/eyJfcmFpbHMiOnsiZGF0YSI6eyJmb3JtYXQiOiJqcGVnIiwicmVzaXplX3RvX2xpbWl0IjpbOTYwLDY0MF0sInNhdmVyIjp7InN0cmlwIjp0cnVlfX0sInB1ciI6InZhcmlhdGlvbiJ9fQ==--4e27bac8cdfb621fb828f6a3a5982fe1a423b516/2026-04-29T01-04-10.643Z-8_DO_MCP23008_9..jpeg)

## Description

**What is it?**

This is an 8-channel industrial relay output module designed for 24VDC control systems, based on the MCP23008 I2C GPIO expander.

It enables a microcontroller or PLC to control real-world loads (AC or DC) through integrated relay outputs, making it ideal for automation, control panels, and embedded systems.

Each output is driven through opto-isolated circuitry and transistor drivers, ensuring reliable switching and improved signal integrity.

**Why this board is different**

Most GPIO output boards:
- Only provide low-voltage outputs (3.3V / 5V)
- Cannot directly drive real loads
- Require external relays or driver circuits

This module provides a complete solution:
- Integrated relay outputs (no external hardware required)
- 24VDC industrial system compatibility
- Optocoupler-driven control for improved reliability
- Designed for real control applications, not just prototyping

👉 You can directly switch relays, solenoids, lamps, and other loads without additional interface circuits

**Key Features**
- 8 × relay outputs (SPST normally open)
- MCP23008 I2C GPIO expander
- Optocoupler-driven relay control
- 24VDC power input
- On-board 24V → 3.3V regulator
- Output status LEDs
- Flyback protection for relay coils
- Configurable I2C address (up to 8 modules)
- Interrupt output (INT)
- Reset signal access
- I2C IN / OUT connectors for daisy-chaining
- Optional onboard I2C pull-ups
- Industrial screw terminal connectors

**Electrical Characteristics**
- Supply voltage: 24VDC nominal
- Logic interface: I2C (3.3V)
- Number of outputs: 8
- Relay type: SPST Normally Open
- Max load current: 5A per channel
- Max load voltage:
- 30VDC
- 250VAC
- Coil voltage: 24VDC
- Coil current: ~8.3 mA per relay

**Typical Applications**
- PLC and embedded controller output expansion
- Industrial automation systems
- Relay and contactor control
- Solenoid and actuator driving
- Alarm and signaling systems
- Remote / distributed I/O systems

**Integration**
- Control outputs via I2C interface
- Daisy-chain multiple modules (up to 8 boards)
- Compatible with STM32, ESP32, and other microcontrollers

Each output can directly switch external loads without additional circuitry.

**How it works**

When a GPIO output is activated:

Optocoupler turns ON
Driver stage energizes relay coil
Relay contact closes → load is powered

When deactivated:

Relay opens → load is disconnected

This architecture ensures reliable switching and separation between logic and field devices

**Important Notes**
- Designed for 24VDC industrial control systems
- Suitable for switching AC and DC loads
- Use proper wiring and load ratings
- Disconnect power before modifying connections
- Ensure loads do not exceed relay ratings