Adafruit PCA9546 4-Channel STEMMA QT / Qwiic I2C Multiplexer

The Adafruit PCA9546 4-Channel STEMMA QT / Qwiic I2C Multiplexer allows you to connect up to 4 same-address I2C devices to one microcontroller, solving address conflicts by multiplexing the I2C bus.

This multiplexer acts as a gatekeeper, forwarding commands to the selected I2C channel with a simple control byte. It operates at I2C address 0x70 (adjustable to 0x77 with jumpers) and supports STEMMA QT/Qwiic connections for easy daisy-chaining of devices without soldering.

The breakout features 5 JST SH 1mm connectors: 1 input and 4 outputs, along with mounting holes and a power LED indicator. It includes an onboard 3.3V 500mA regulator to enable level shifting for 5V microcontrollers.

Features:

• Supports up to 4 same-address I2C devices
• I2C address default 0x70, adjustable from 0x70 to 0x77 via jumpers
• Five JST SH 1mm STEMMA QT / Qwiic connectors (1 input, 4 output)
• Onboard 3.3V 500mA regulator and level shifting for 5V logic
• Compact size: 25.3mm x 20.3mm x 4.8mm
• Power LED indicator
• Compatible with STEMMA QT and Qwiic ecosystems

Note: Board comes assembled without cables or sensors.