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(ADV7480)Mipi undershoot

Question asked by donadona999s on Sep 11, 2017
Latest reply on Sep 28, 2017 by donadona999s

Hi !

 

I have some questions about ADV7480.

I asked about MIPI line at this session.

(ADV7281-M) Some question about video network. 

The device is not same but I think you can say same thing to ADV7480 Mipi-line.

At the thread, ADI's answer is this

 

Q2) and Q3)

All termination for the MIPI lines are controlled by the MIPI D-PHY physical layer in the ADV728x-M and the MIPI D-PHY physical layer in the reciever chip. I strongly advise not placing any other components on the MIPI lines as doing so could violate MIPI D-PHY specifications.

See layout recommendations in the link below for more information.  http://www.analog.com/media/en/technical-documentation/application-notes/AN-1337.pdf 

And I said to my customer same thing.

But our customer have some undershoot problem

 

The mipi pin signal voltage range specification is -50~1350mV.

But the yellow line looks it is very close to -50mV.

 

Q1)

Do you think would this undershoot cause any problem?

 

Q2)

Can you give some advice why this happen?

Only the PCB layout is the reason?

 

Q3)

If I gave you our customers PCB layout, can you revue it?

 

Best regards

Kawa

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