TDP0604: Question on the HPDOUT_SEL pin

Roy Hsu

Part Number: TDP0604

Hi Team,

I'm not quite clear about the description on the HPDOUT_SEL pin in the datasheet. It says open-drain is not supported in pin-strap mode so this pin should be left floating or pulled down. Does it mean that we only need to pull this pin high when we're in I2C mode and if we need this pin to be open-drain?

Thanks!

Roy

over 2 years ago

0 David (ASIC) Liu over 2 years ago

TI__Guru**** 176781 points

Roy

In pin-strap mode, the HPD_OUT is always push/pull.

In I2C mode, you can configure HPD_OUT to be push/pull or open-drain through register 0x0A.

Thanks

David

0 Roy Hsu over 2 years ago in reply to David (ASIC) Liu

TI__Genius 9390 points

Hi David,

If open-drain's not supported in pin-strap mode, then why did we need this pin on our device?

Thanks!

Roy

0 Zach Dryer over 2 years ago in reply to Roy Hsu

TI__Genius 13310 points

Hello, Roy,

Is there some context to this question to which you can refer me?

Are you asking about a particular design or why we have HPDOUT_SEL pin in general?

We have this pin on the device so that the customer can use I2C mode to use open drain if they desire that functionality.

Thanks,
Zach

0 Roy Hsu over 2 years ago in reply to Zach Dryer

TI__Genius 9390 points

Hi Zach,

Yes, my question is why we have HPDOUT_SEL pin in general.

David (ASIC) Liu said:
In pin-strap mode, the HPD_OUT is always push/pull.

Since HPD_OUT is always push-pull in pin-strap mode and selecting between open-drain and push-pull in I2C mode is irrelevant to HPDOUT_SEL , why bother having HPDOUT_SEL pin?

Thanks!

Roy

0 David (ASIC) Liu over 2 years ago in reply to Roy Hsu

TI__Guru**** 176781 points

Roy

Please see my direct email response.

Thanks

David

0 Zach Dryer over 2 years ago in reply to Roy Hsu

TI__Genius 13310 points

Hello, Roy,

In I2C mode, the user can select between an HPD_OUT open-drain or HPD_OUT push-pull. Therefore, you need this pin so that the user can choose to enable HPD_OUT open-drain if they would like to use that functionality instead of the defaulted HPD_OUT push-pull.

In pin strap mode, the user only has the push-pull option. Thus, this pin is left floating in this mode or pulled down to GND.

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TDP0604: Question on the HPDOUT_SEL pin