TMDS181: TMDS181 impedance test waveform is abnormal

William Zhang2

Part Number: TMDS181

Hi team,

Customer is testing the waveform of HDMI1.4 impedance of TMDS181 (measured without power supply) shown as below picture:

The Chinese meaning in the picture is: the normal test impedance should be infinite

Generally, the impedance of the test without power should be infinite.

Could you give any advice? Thanks.

0 David (ASIC) Liu over 4 years ago

Hi,

Do you have a block diagram of their setup? Is this a source or a sink TDR test they are running?

Can you also mark on the TDR where the TMDS181 impedance is?

Thanks

David

0 William Zhang2 over 4 years ago in reply to David (ASIC) Liu

Hi David,

1、The block diagram is shown as below. It's a sink TDR test, and the test point is the HDMI Port in below picture.

2. The circled part in the figure below looks like the TDR waveform inside the TMDS181.

0 David (ASIC) Liu over 4 years ago in reply to William Zhang2

Hi,

Infinity means an open circuit, why do they expect to see an infinity when they plug into the TMDS181 input?

I verified in the lab on a TMDS181 EVM that the TDR matches with their measurement.

Thanks

David

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