TPD8S009: ESD protection for display port introduce noise in my signals

Tsvetomir Asenov

Part Number: TPD8S009
Other Parts Discussed in Thread: TPD4E02B04

Hello,
I am using DP to eDP 4 lane interface board.

For ESD protection I have placed TPD8S009DSMR part to protect my device, but i see when solder the TPD8S009DSMR on the board, the quality of the signal gets worse.

I have tested it without the TPD8S009DSMR, and everything works fine.
The issue is that when TPD8S009DSMR is soldered, i can see instability in the vide of the panel I am using, something similar to flickering (garbage or so).

The 5 volts are provided from and LDO, which is powering a pwm circuitry as well.

Do you have any recommendation?

Thanks

4 months ago

+1 Josh Prushing 4 months ago

TI__Expert 5210 points

Hi Tsvetomir,

Could you please confirm the DisplayPort version you are using? I anticipate that the capacitance may not be high enough to support the data rates.

I anticipate your response, please let me know if you have any additional questions!

Best Regards,

Josh Prushing

0 Tsvetomir Asenov 3 months ago in reply to Josh Prushing

Prodigy 150 points

Hello Josh,
It is mini DP 1.4

0 Josh Prushing 3 months ago in reply to Tsvetomir Asenov

TI__Expert 5210 points

Hi Tsvetomir,

Thank you for providing this information!

As noted above, TPD8S009DSMR has too high of a capacitance for the data speeds present on these lines. The device we typically recommend for DisplayPort 1.4 protection would be TPD4E02B04. This device has a capacitance of 0.25pF (TPD8S009 has 0.8pF), and this makes a tremendous difference in the data speeds that the device can support. For more information on this, please see our app note titled "Capacitance Requirements for High Speed Signals" featured on our DisplayPort FAQ page!

This FAQ page is also a great resource if you have any additional questions for DisplayPort, or any other interface questions you may have!

Please let me know if you have any additional questions, or if you need help locating anything!

Best Regards,

Josh Prushing

0 Tsvetomir Asenov 3 months ago in reply to Josh Prushing

Prodigy 150 points

Hello,
Yes that makes sense.

Since I use 4 lane ( 8 signals ) and the IC that you are recommending has only 4 channels, do you have the same TVS package but for 8 channels?

Thanks!

0 Josh Prushing 3 months ago in reply to Tsvetomir Asenov

TI__Expert 5210 points

Hi Tsvetomir,

We unfortunately do not have any low enough capacitance devices in the 8 channel configuration. We do have a 6 channel device (TPD6E05U06), but the capacitance for this device is 0.5pF, which may present similar signal integrity issues to what you were seeing with TPD8S009, especially considering the requirements outlined in the app note I mentioned previously.

Best Regards,

Josh Prushing

0 Tsvetomir Asenov 3 months ago in reply to Josh Prushing

Prodigy 150 points

Hi Josh,
Then Can I try to use 2x TPD4E02B04 for my application?

Thanks,
Tsvetomir

+1 Josh Prushing 3 months ago in reply to Tsvetomir Asenov

TI__Expert 5210 points

Hi Tsvetomir,

Yes, that is our recommended solution! 2x TPD4E02B04 will support all of the signal lines for DisplayPort 1.4. Apologies for the confusion!

Please let me know if you have any other questions!

Best Regards,

Josh Prushing

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TPD8S009: ESD protection for display port introduce noise in my signals