DS90UB954-Q1: PoC circuit issue

Rupesh Malavi

Part Number: DS90UB954-Q1
Other Parts Discussed in Thread: DS90UB935-Q1,

Hi Team TI,

We are using DS90UB954-Q1 deserializer along with DS90UB935-Q1 Serializer.

We are facing link detection issue in syncronous mode.

We suspected issue in PoC section as noise was more at co-axial cable. So we isolated complete PoC section from serializer & deserializer section and provided standlone power supply.

Now link is stable and able to write & read serializer register.

Please review the PoC section & let us know the changes or any calulation formula is available to do so.

Current PoC circuit is based on PoC PPT shared by TI over the mail.

over 3 years ago

0 Jiashow Ho over 3 years ago

TI__Genius 11340 points

Hi Rupesh,

The image is broken. Could you reattach it?

Best,

Jiashow

0 Rupesh Malavi over 3 years ago in reply to Jiashow Ho

Prodigy 245 points

Hi Jiashow,

Please find the attached zip file for PoC Circuit.

PoC Circuit.zip

0 Jiashow Ho over 3 years ago in reply to Rupesh Malavi

TI__Genius 11340 points

Hi Rupesh,

It looks like you're using a network different from what we recommend in the datasheet. Is this running in sync or non-sync mode? What's the max current that needs to be supported? If possible we suggest using the network in the datasheet.

Jiashow

0 Rupesh Malavi over 3 years ago in reply to Jiashow Ho

Prodigy 245 points

Hi Jiashow,

Mode = Sync Mode

Now with basic fuctionality & power on it will take ~400mA & when camera streaming it may take arround 600mA to 700mA.( yet to stream camera).

PoC network kept as per " PoC solution PPT" provided by TI FAE over the mail communication.

0 Casey McCrea over 3 years ago in reply to Rupesh Malavi

TI__Guru* 98415 points

Hello Rupsesh,

Can you link us with the TI FAE? That way we can close the loop?

Thanks,
Casey

0 Rupesh Malavi over 3 years ago in reply to Casey McCrea

Prodigy 245 points

Hi Casey,

Please check below TI FAE Contact.

shashanksm@ti.com

0 Jiashow Ho over 3 years ago in reply to Rupesh Malavi

TI__Genius 11340 points

Hi Rupesh,

Do you have he PN of the 2.2uH and 10uH that you used?

Have you done measurements for PoC noise? What's the noise from the output of the PoC supply? If you increase the PoC voltage did the issue go away?

Best,

Jiashow

0 Rupesh Malavi over 3 years ago in reply to Jiashow Ho

Prodigy 245 points

Hi Jiashow,

Please check below MFG PN for inductors,

1) 2.2uH = ADL3225VM-2R2M ( TDK Corporation)

2) 10uH = ADM45FDC-100M ( TDK Corporation)

Please check the below scope shot for PoC ripples measured at SMA connetors after PoC circuit.

MB-SMA = Main board PoC @SMA Conn = 660mV

CAM-SMA = Camera board PoC entry @SMA Conn = 664mV

0 Jiashow Ho over 3 years ago in reply to Rupesh Malavi

TI__Genius 11340 points

Hi Rupesh,

The PoC network you're using is one of our recommended ones. We've done validation with that network.

The issue is most likely related to your PoC noise. The Vpoc noise on the regulator entry on the serializer board should be 100mVpp or less for reliable operation. Try adding decoupling caps, use a different PoC source, and increasing the PoC voltage to reduce the noise.

Also, I suggest running the margin analysis on the system to check for how much margin you have. Refer here:

Best,

Jiashow

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DS90UB954-Q1: PoC circuit issue