TUSB2077A BUSPWR signal

Peter Clerico

Other Parts Discussed in Thread: TUSB2077A

Hello - can you confirm the polarity of the !BUSPWR signal? There appears to be disagreement over the assignment of BUSPWR in the application examples (data sheet pp 12, 13, 14) compared to its pin description. For example, it is tied low in the bus-powered example, and tied high in the self-powered examples, which is contrary to its pin description.

I also looked at the TUSB2046 - its application examples match its BUSPWR pin description better. It seems odd that the TUSB2077's !BUSPWR pin name has an active-low connotation, when it's described as active high.

Thanks in advance.

Peter Clerico

over 14 years ago

0 Michael Peffers over 14 years ago

TI__Mastermind 20820 points

Hi Pete,

I agree with you that there is some dicrepency in what the pin discription and the application designs. I will check with the correct departmart and back to you as soon as I hear something from them.

Mike Peffers

0 Michael Peffers over 14 years ago in reply to Michael Peffers

TI__Mastermind 20820 points

Pete,

I heard back from the department this morning that deals in the TUSB2077A and they confimred with me that the data sheet for the TUSB2077A is incorrect. The BUSPWR pin is in fact active low.

-Mike

0 Peter Clerico over 14 years ago in reply to Michael Peffers

Intellectual 550 points

Thanks Mike,

From this, it seems to me the Terminal Description on data sheet page 4 is incorrect in its statement:

For the bus-power mode, this terminal must be pulled to 3.3 V, and for the self-powered mode, this terminal must be pulled low". Should these assignments be reversed?

If this is the case, then the application diagrams on pages 12/13/14 are correct. Can you confirm this?

Thanks again