TUSB8041: Getting 1.8V on TUSB8041 GRSTz pin

Kevin Lin

Part Number: TUSB8041

Hi There,

I am getting approximately 1.8V on GRSTz pin, as well as BATEN and OVERCUR pins, but not all of them. On each board, I at least got one OVERCUR and one BATEN at 1.8V, and GRSTz is 1.8V on all boards. Where should I look into for this issue? By the way, my circuit is almost identical to AM572xEVM. Thank you

Regards,

Kevin

over 8 years ago

0 Gerardo over 8 years ago

TI__Genius 11280 points

Hello Kevin,
We will check you question.

Regards,
Gerardo

0 Kevin Lin over 8 years ago in reply to Gerardo

Expert 1445 points

Hi Gerardo,

Do you have any suggestion for me where to look into the issue yet?

regards,

Kevin

0 Elias Villegas M. over 8 years ago

TI__Guru* 76130 points

Hello,
Please provide your schematic, are you following the power-up sequence?
Are you soldering the thermal pad to GND?
Is the hub being enumerated by the host?

0 Kevin Lin over 8 years ago in reply to Elias Villegas M.

Expert 1445 points

Hi Elias,

Here is our power-up sequence. Does it look right to you?

regards,

Kevin

0 Kevin Lin over 8 years ago in reply to Elias Villegas M.

Expert 1445 points

Hi Elias,

Regarding to the power-up sequence, I have a question. In the figure 2 of the datasheet, it states that Vdd33 needs to be stable td1 before Vdd, but the note (2) above says there is no power-on relationship between Vdd33 and Vdd unless GRSTz is only connected to a capacitor to GND. So, when GRSTz is only connected to a capacitor to GND, the power-on sequence in the figure 2 doesn't apply, and Vdd must be stable at least 10us bofore Vdd33?

regards,

Kevin

0 Elias Villegas M. over 8 years ago in reply to Kevin Lin

TI__Guru* 76130 points

Hello,

Correct, when GRSTz is only connected to a filter capacitor then VDD11 must be stable at least 10us before VDD33, also GRSTz must remain asserted at least 3ms after VDD33.

Regarding the schematic, the voltage on terminal USB_VBUS does not look correct, when USB_VBUS is connected to +5V the voltage divider must be 90.9K//10K

Regards

Interface

Interface forum

TUSB8041: Getting 1.8V on TUSB8041 GRSTz pin