DS92LV2411/2 ESD issue

Hi Gan Wei,

Can you provide more details about your test setup? When you suggest that there is 6 kV applied, it sounds like an ESD test rather than an EMI test. However, to help me understand, can you detail how you are doing your setup? Scope shots of the phenomenon would also be helpful.

I looked at the schematic and everything looks reasonable for the Tx side (DS92LV2411). Is there a DS92LV2412 Rx side to the schematic? I only can view one page, and the page contains the DS92LV2411.

Thanks,

Michael

DISP-LCD.PDFHi Michael,

Yes, it is ESD test rather than EMI, sorry for the mistake. Schematic for DS92LV2412 is sent again in the attachment, test setup and screenshot will be arranged and uploaded later.

Thank you!

Hi Gan Wei,

I looked at the DS92LV2412 schematic as well, and it looks reasonable to me. 

It seems to me that you are performing some kind of system ESD testing as opposed to an ESD test specifically on one device, like what we put in our datasheet. Therefore, it would be good for me to understand where you are performing the measurement and how the waveforms of the incoming data to the DS92LV2412 change as a result of the ESD strike.

Lastly, can you explain what this 6 kV test is used for? Do you have a product requirement to pass without issues with 6 kV ESD, or is it higher or lower?

Regards,

Michael

Hi Michael,

The 6KV ESD Strike is performed on the casing of product by ESD GUN.

Hi Gan Wei,

Please upload setup block diagram and screenshots when you have a chance.

In addition to previous questions:

1. When you see this issue, which device are you sending the ESD strike to? The Tx or Rx? Both?

2. Does this ESD issue happen to all DS92LV2411/12 devices, or does it only happen to a subset of them?

Thanks,

Michael

Hi Michael,

The ESD strike is send to product case,not to the device(DS92LV2411/12), it should be a system ESD test. In this case, what shall i do to solve this problem?

Hi Gan Wei,

Thanks for the clarification. If this is a system ESD test, it is much more difficult to diagnose the issue. There are many different points of issue that can cause ESD failure in the presence of Channel Link devices, so I am afraid I will not be able to tell you a definite solution to this issue. It will take several iterations of trial and error.

In the past, we have been able to improve the ESD resilience with the following. I suggest considering and trying some of these ideas:

• Add more caps on the supplies to improve power supply decoupling
• Consider using different cables or cable vendors to interface between DS92LV2411 and DS92LV2412. Different cables can sometimes make a large difference in the presence of system ESD.
• Review the layout and determine if there are issues such as cross-talk coupling that can cause a strike in one part of the system from coupling into the DS92LV2411 and DS92LV2412 path.

Thanks,

Michael

Hi Michael,

We recently have the time to test some waveform and upload the operation details.  

Flexible Flat Cable(The length is about 25cm) is used to connect DS92LV2411 and DS92LV2412,  we test waveform on DS92LV2412.

8KV Air Discharge test is OK, but 6KV  Contact Discharge cause the flash screen. In 6KV  Contact Discharge ESD test, we send strike to screen and send strike to metal -flat which contact the DUT shell.

Please refer to attachment, which include following:

1.  Test operation details;

2. "PASS" and "LOCK” waveform seem to be abnormal when ESD strike.

Please help to analyze.

Hi Gump,

It looks like the ESD strike may be affecting the serial interface between the DS92LV2411 and DS92LV2412 based on your description and the waveform you have provided from the LOCK pin.

I am wondering if inserting an ESD protection diode in the path between DS92LV2411 and DS92LV2412 may help. Looking at your schematic, I am only able to see the 0.1 uF cap at RIN+/-. Since the issue is due to system-level ESD, I would recommend in addition to what I have already suggested above to give devices like the TPD2E009 a try, as it can help protect +/8kV contact discharge.

Thanks,

Michael

Hi michael,
I follow your suggestion,and add the TPD2E009 between DS92LV2411 and DS92LV2412(close to DS92LV2412), but this issue do not have any improvement.
Do you have other suggestion?

Hi Gump,

Thanks for your patience as we were out on a break for New Year's Holiday.

Since we have already tried adding ESD caps, have you considered adding a common mode choke? I wonder if a common mode choke coil may help?

Also, have you tried using flex cables from other vendors? Sometimes different quality in the same cable type can help provide robustness for ESD testing.

Thanks,

Michael