TCA9548A 8-Channel I2C Multiplexer Breakout Board | ATMOSFÆR ENGINEERING

I2C multiplexer expansion module that splits one I2C bus into 8 independent channels, solving address conflicts and enabling connection of multiple identical I2C devices. Supports up to 8 different I2C addresses (0x70-0x77) allowing for massive bus expansion. Ideal for projects requiring multiple sensors with the same address or extending I2C bus reach beyond standard limits.

Technical Specifications:

• IC: TCA9548A I2C Multiplexer
• Interface: I2C (TWI)
• Channels: 8 independent I2C buses
• Operating Voltage: 1.65V - 5.5V (wide voltage compatibility)
• I2C Address Range: 0x70 - 0x77 (configurable via solder jumpers)
• Maximum Clock Frequency: 400kHz (I2C fast mode)
• Logic Level: 3.3V and 5V compatible
• Channel Selection: Software-controlled via I2C command
• Current Consumption: Low standby current
• Operating Temperature: -40°C to +85°C (typical)
• Board Dimensions: ~20mm x 25mm (typical breakout size)

Features:

• Splits 1 I2C bus into 8 independent channels
• Solves I2C address conflicts (use 8 identical sensors)
• Bidirectional buffering on all channels
• Software-controlled channel selection
• Multiple boards can be chained (up to 8 multiplexers = 64 channels)
• Wide voltage range (1.65V - 5.5V)
• Hot-insertion capable on downstream channels
• No additional components required
• Enables extended I2C bus lengths

Pin Configuration:

• VIN/VCC: Power supply (1.65V - 5.5V)
• GND: Ground
• SDA: Main I2C data line (upstream)
• SCL: Main I2C clock line (upstream)
• SD0-SD7: 8 independent I2C data channels
• SC0-SC7: 8 independent I2C clock channels
• RST: Reset pin (optional)
• A0-A2: Address selection jumpers

Address Configuration:

• Solder jumpers A0, A1, A2 select base address
• Available addresses: 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77
• Allows up to 8 TCA9548A boards on same I2C bus

How It Works:

1. Connect microcontroller I2C to main SDA/SCL
2. Connect up to 8 I2C devices to channels SD0-SC0 through SD7-SC7
3. Send I2C command to TCA9548A to select active channel(s)
4. Communicate with device on selected channel(s)
5. Switch channels as needed via software

Applications:

• Using multiple sensors with identical I2C addresses
• Extending I2C bus beyond capacitance limits
• Isolating noisy I2C devices
• Multi-sensor arrays (8x of same sensor type)
• Long-distance I2C communication
• Hot-swappable I2C device connections
• Complex sensor networks
• Industrial monitoring systems with many identical sensors

Use Cases:

• 8x identical temperature sensors (all address 0x48)
• Multiple OLED displays with same address
• Sensor arrays for environmental monitoring
• Modular robotics with interchangeable I2C modules
• IoT sensor networks

Important Notes:

• Each channel can have multiple I2C devices (standard I2C rules apply)
• Multiple channels can be active simultaneously (if needed)
• Reduces I2C bus capacitance issues by segmenting bus
• Does not increase total I2C device count limit (still 127 addresses per channel)
• Requires pull-up resistors on main bus and individual channels

Expansion Example:

• 1 TCA9548A = 8 channels
• 8 TCA9548A boards = 64 channels
• Connect 64 identical I2C sensors from 2 GPIO pins

Typical Wiring:

• Main Bus: Microcontroller SDA/SCL → TCA9548A SDA/SCL
• Channel 0: TCA9548A SD0/SC0 → Sensor 1
• Channel 1: TCA9548A SD1/SC1 → Sensor 2 (same address as Sensor 1)
• ... and so on

Compatible with Arduino, ESP32, Raspberry Pi, STM32, and any microcontroller with I2C support. Libraries available for easy channel switching and device management.