TUSB8020B: Use both pin function of a single pin

David Kirschner21

Part Number: TUSB8020B

Hello,

I was wondering, how can one use both functionality of a single pin? They seem, they are not complementary functions. For example:

Pin22: SMBUSz/SS_DN2. I will pull it up with a resistor to select I2C mode, but than i loose the SuperSpeed USB connection status of the downstream port2.

Pin36: FullPWRMGMTz/SMBA1/SS_UP: this pin has even 3 functions. If i pull down, power switching is selected, but i lost the other 2. (In my case SMBA is not relevant, but i am interested in the proper solution).

What is the right way to configure these pins?

Thank you in advance!

Best regards,
David

over 7 years ago

0 Clemens Ladisch over 7 years ago

Guru 317060 points

When the chip is powering up, the pins are inputs, and the TUSB reads them to detect the presence of the pull-up resistors.
Later, when the chip is running, the pins are outputs.

The pull-up resistors are (supposed to be) so weak that they do not interfere with the output signal.

0 David Kirschner21 over 7 years ago in reply to Clemens Ladisch

Prodigy 75 points

I see, thank you very much!

Interface

Interface forum

TUSB8020B: Use both pin function of a single pin