• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 33 subscribers
  • Views 383 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

TCA9555 SDA, SCL and INT pins

TCA9555: SCL/SDA above Vcc / interfacing to TCA9548 with higher Vcc

David D
Intellectual 580 points
Part Number: TCA9555

Hello,

Can you please confirm that operating TCA9555 with TCA9548 as described below is a valid usage of both devices?:

In my design I use TCA9548 (I2C switch) to drive the downstream TCA9555.

TCA9548 has Vcc =3.3V

TCA9555 has Vcc=1.8V

Pullup resistors are connected to 1.8V. Yet according to TCA9548 datasheet Vpass(@Vcc=3.3V)=~2V, which is higher than the 1.8V pullup voltage and the Vcc of TCA9555 . Meaning the output voltage may go higher than 1.8V and thus TCA9555 will experience input level above its Vcc. (Is my understanding correct?)

Note that it's not a power sensitive application so ,let's say x2 rise in Icc is not a concern here .

Regards,

David.

  • 0
    TI__Guru 73001 points

    Hey David,

    You are correct. When TCA9548 is tied to Vcc = 3.3V then the lowest level of translation on the secondary channels allowed is about 2V. So if you were to connect it to 1.8V then you may lose the level translation feature and see leakage current into the secondary channel as well as a lower voltage on higher channels when the channel is enabled.

    Can you set Vcc of TCA9548 to 1.8V instead? This would resolve the issue.

    -Bobby