TUSB522P: Question about OS PIN

Seokmin Hong

Intellectual 485 points

Part Number: TUSB522P

Hi, I am going to use TUSB522p for my USB System.

I have a simple question.

In the datasheet, in the typical application like below,

OS1 and OS2 Pins are both Pull-Up, and Pull-down with 47k Ohm.

I understand that EQ, and DE pins have Mid level input, but OS1 and OS2 Pins only have High or Low Cmos input.

If I put both pull up and pull down like typical application then what logic value will OS1 and OS2 will have?

Thanks.

over 3 years ago

0 Malik Barton57 over 3 years ago

TI__Guru 64326 points

Hi,

The OS state will be undetermined if both pull-up and pull-down resistors are installed. I recommend setting these pins to high by installing the pull up resistors only. Figure is meant to show the possible options.

0 Seokmin Hong over 3 years ago in reply to Malik Barton57

Intellectual 485 points

Hi Malik.

Then when is needed OS State High or Low?

If line is long then should I make OS state to be High to make amplitude bigger?

Thanks.

0 Malik Barton57 over 3 years ago in reply to Seokmin Hong

TI__Guru 64326 points

Hi,

That is correct, OS high will help to maintain a good vertical eye height. If you have some mux in the path that requires a lower Vpp then OS low could be used.

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TUSB522P: Question about OS PIN