TCA9548A: Can TCA9548A support 1.8V bus when VCC=3.3V ?

Miranda Gu

Part Number: TCA9548A

Hi team,

Can TCA9548A support 1.8V bus when VCC is 3.3V?

From datasheet, as shown below, Vpass is about 2V when VCC=3.3V, each bus voltage should be equal or beyond Vpass (2V), so I think TCA9548A cannot support 1.8V bus when VCC is 3.3V. Please correct me if I am wrong, thank you!

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 243820 points

Voltages above Vpass are clamped to Vpass.

If both buses use 1.8 V, then this will work fine. You get a problem only if you try to translate a higher voltage to a voltage below Vpass.

0 Miranda Gu over 3 years ago in reply to Clemens Ladisch

TI__Genius 14827 points

Hi Clemens,

Thanks for your reply!

My customer try to use TCA9548A to translate 3.3V to 1.8V when VCC=3.3V. So TCA9548A cannot support this application, right?

And my customer did bench test, TCA9548A output is ~2V not 1.8V, which verified the analysis.

Please kindly confirm, thank you!

0 BOBBY over 3 years ago in reply to Miranda Gu

TI__Mastermind 49270 points

Hi Miranda,

Clemens is correct. At Vcc=3.3V, the device will only support level translation down to 2V or higher.

If you need to support 1.8V, you can place the Vcc of the device to 1.8V

-Bobby

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TCA9548A: Can TCA9548A support 1.8V bus when VCC=3.3V ?