TCA9546A: For Vcc=3.3V, will the level translation work from 3.3V to 1.8V SDA/SCL is 3.3V and SD2/SC2 is 1.8V.

Farshad Farahbakhshian

Prodigy 330 points

Part Number: TCA9546A

I am planning to use TCA9546 as a I2C Mux and a level translator.

For Vcc=3.3V, will the level translation work from 3.3V to 1.8V

SDA/SCL is 3.3V and SD2/SC2 is 1.8V.

over 7 years ago

0 Miguel Robertson over 7 years ago

TI__Guru 62920 points

Hi Farshad,

When VCC is 3.3 V, the device's internal pass gate voltage for each channel's switch will be at about 2 V (see Figure 16 in the datasheet). This means that voltages below 2 V on either side of the switch will result in conduction between the two sides, meaning unfortunately you will observe some leakage from your 3.3-V rail to your 1.8-V rail. To prevent this, you would need to keep VCC below 3 V.

Regards,
Max

0 BOBBY over 7 years ago

TI__Guru 63530 points

Hey Farshad,

Just to give you more information in case you were interested, a similar question was asked not too long ago:

TCA9548A: Can use 3.3V and 1.8V at same time? - Interface forum - Interface - TI E2E support forums

e2e.ti.com

Part Number: TCA9548A Dear Team, Could I pull up two different voltage on different I2C bus at the same time? For example, use 3.3V on SC0 and use 1.8V on

The answer goes into a deeper explanation of why 3.3V as Vcc will not work.

-Bobby