TPD12S521: HDMI source TMDS characteristics standby test

Vincent Li00

Intellectual 2035 points

Part Number: TPD12S521

Hi Guys

Please find my schematic about the HDMI Redriver and ESD sction.

Schematic:

About the HDMI classifacation test. the standby test. They need powet off the HDMI device and the equipment. And add a 3.3V(50ohm pull up) on the TMDS signal wire, and then test the signal voltage y using DMM. The requirement is 3.3V +/- 10mV. But so far they just got 2.6V. So how to solve this problem? Or did we meet the same quesiton before?

Please pay attention the attachment about the classificaiton test about the Voff test.

HDMI Classifacation requirement:

Your feedback are very appreciated.

Thanks

-Pengfei

over 4 years ago

0 Michael Tan over 4 years ago

TI__Expert 8420 points

Hi Vincent,

I try to know your question.

"The requirement is 3.3V +/- 10mV. But so far they just got 2.6V." Where the 2.6V come from? Can you set it to 3.3V ?

0 Vincent Li00 over 4 years ago in reply to Michael Tan

TI__Intellectual 2035 points

Hi Michael

We do add a 3.3V(50ohm pull up) on the TMDS signal wire, and then test the signal voltage by using DMM. result is 2.6V

0 Michael Tan over 4 years ago in reply to Vincent Li00

TI__Expert 8420 points

Hi Vincent,

The TMDS line internal is only have the ESD by pass .

You add the 3.3V in the TMDS pin it should not have any leakage current in the TPD12S512 internal pin.

I suspect the front end device IO pin (before TPD12S512) may sink current that will let the voltage drop to 2.6V.

To verify this, you can solder out the front end device any apply the 3.3V to the TMDS pin and double confirm.

Interface

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TPD12S521: HDMI source TMDS characteristics standby test