TUSB320: VBUS_DET pull up / Operating out of spec

Part Number: TUSB320

Hi Team,

We are currently using the chip TUSB320I in our project BI 40X and I was wondering what would be the impact on the chip’s behavior if VBUS_DET’s pull-up resistor (R83 in my schematic below) was 9k ohm instead of 900k ohm.

Also, I currently have a board with this configuration and when I connect a USB C connector in the socket, VBUS is at 5V and the VBUS_DET pin is at 3.82V, which is weird because I should have 4.56V with the 95k ohm internal pull-down resistor. Perhaps there is an internal diode limiting the voltage on this pin?

In any case, 3.82V is still below the 4V Absolute Maximum Rating. All the functionalities are working properly at the moment.

Can there be any long-term consequences of using this chip in this configuration?

Regards,

over 4 years ago

+1 Malik Barton57 over 4 years ago

TI__Guru 64326 points

Hi RJ,

TUSB320I using a 9K resistor will not protect the pin from VBUS voltage spikes higher than 5V. VBUS_DET pin voltage should be ~10% of Vbus for expected operation. TUSB320I was not test with this resistance so I cannot comment on the long term consequences. ~900K resistor should be used on VBUS_DET pin. Also I recommend should using PN: TUSB320LAI.