Need to use multiple I2C devices that share the same address? The PCA9546 4-Channel I2C Multiplexer lets you connect up to four same-address I2C devices to a single microcontroller by acting as a gatekeeper — write a single byte to select the active channel and all subsequent I2C traffic is routed to that port.

The multiplexer sits at I2C address 0x70 (adjustable from 0x70 to 0x77 via solder jumpers). With eight possible multiplexer addresses, you could theoretically control up to 8 × 4 = 32 same-address devices on one I2C bus.

Key Features

• 4 Multiplexed I2C Channels – Route I2C traffic to any of four downstream buses
• Simple Control – Write a single byte to select the active channel; all further I2C packets go to that port
• Configurable Address – Default 0x70, adjustable to 0x70–0x77 for up to 8 multiplexers on one bus
• 3 V and 5 V Compatible – Works with any logic level
• STEMMA QT / Qwiic Connectors – Solderless I2C connection on the upstream side
• Breadboard Friendly – Breakout PCB with capacitors, pull-ups, and pull-downs included

How It Works

The PCA9546 acts as an I2C switch. Your microcontroller sends a command byte to the multiplexer's address (0x70 by default) specifying which downstream channel to activate. All subsequent I2C communication passes through to the selected channel. You can enable multiple channels simultaneously if needed.

Ideal For

• Using multiple identical I2C sensors (same address) on one bus
• Isolating I2C bus segments to avoid address conflicts
• Expanding I2C capacity on address-limited projects
• Sensor arrays and multi-sensor data logging

Package Contents

• 1× Adafruit PCA9546 4-Channel I2C Multiplexer breakout, assembled

Resources

• What is STEMMA QT? – Introduction to the STEMMA QT connector system