DS90UB953-Q1: DS90UB953-Q1 EMC Issue

Shay Carmel

Prodigy 10 points

Part Number: DS90UB953-Q1

Hi Guys,

We are using in our camera serilaiser P/N DS90UB953.

We are in the stage of EMC testing.

during emission radiation tests we found some harmonics of 753KHz between 1.5GHz to 1.6GHz, see below.

The noise was measured with pin probing near the DS90UB953, close to the VDD_PLL pins passive components.

We have two requests regarding it:

1. Are you familiar with this problem?

2. Can we receive the DS90UB953 EVB design files so we can see the layout

design (not just the gerbers copy on the EVB datasheet)?

Thanks

Shay

over 3 years ago

0 Nicholas Darash over 3 years ago

TI__Mastermind 18755 points

Hello Shay,

The best way to improve your EMC performance is with better layout and better grounding. Typically good grounding and good enclosures have the largest affect on EMC performance. I cannot share the EVM source files on the public forum, can you request these files from your local TI sales rep?

Regards,

Nick

0 Shay Carmel over 3 years ago in reply to Nicholas Darash

Prodigy 10 points

Hi Nicholas,

Thanks for replying.

We are familiar with the theory. We just want to know if you are familiar with that particular phenomenon.

Regarding the EVKIT files, I will address our local representative.

Thanks

Shay

0 Nicholas Darash over 3 years ago in reply to Shay Carmel

TI__Mastermind 18755 points

Hi Shay,

I will send the files with the FAE. Also 1.6G sounds like the CSI port. You could try running a test with the port disabled to verify and the shield appropriately. Let me know if this isolates it.

Regards,

Nick

0 Shay Carmel over 3 years ago in reply to Nicholas Darash

Prodigy 10 points

Hi Nick,

we ran the test without the CSI port active. So only the link is active.

Regarding the frequency of the specific harmonic which is 753KHz, does this frequency familiar to you? Can it be related to PLL setup, equalizing, or something like that?

Thanks

Shay

0 Nicholas Darash over 3 years ago in reply to Shay Carmel

TI__Mastermind 18755 points

Hi Shay,

753kHz is a strange value, I don't recognize it as being part of our device. What does your setup look like? Are you operating in sync or non-sync mode with a local oscillator?

Regards,

Nick

0 Shay Carmel over 3 years ago in reply to Nicholas Darash

Prodigy 10 points

Hi Nick,

We are working in synchronous mode.

Regards

Shay

0 Nicholas Darash over 3 years ago in reply to Shay Carmel

TI__Mastermind 18755 points

Are you using an SSC?

Regards,

Nick

0 Shay Carmel over 3 years ago in reply to Nicholas Darash

Prodigy 10 points

Hi Nick,

Two things:

1. We are not familiar with the term SSC, and we didn't find any reference to that on the datasheet. Do you mean spread spectrum?

2. I am leaving Adasky in the next two weeks, Amotz katz will take care of this issue, I think that you know him from previews issues.

Thanks

Shay

0 Nicholas Darash over 3 years ago in reply to Shay Carmel

TI__Mastermind 18755 points

Hi Shay,

Yes, I was referring to a spread spectrum clock, are you using one in your system? As for the 1.6G frequency I think we do see some spikes at the range, I am not sure about the harmonic frequency. Have you been able to find a solution or considered using an SSC?

Also glad to work with you all, let me know if the issue persists we can continue to help find a solution.

Regards,

Nick