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CFAG320240CX-TMI-T Proper Grounding / EMI Protection

neonsee

New member
Hello,

we intend to use CFAG320240CX-TMI-T displays in our sun simulators. Each time the xenon discharge lamp is ignited, there is a quite big EMI pulse that freezes the display. Can perhaps anybody tell me how to archive the optimal grounding set-up for a maximum EMI/ESD protection? The Display is mounted directly on top of the µc-PCB with a multipoint connector (no ribon cable is used), and the complete set-up is in a closed metal box. Should the jumpers JF1 (mounting holes to the bezel’s grounding tabs) and/or JF2 (signal ground to the bezel’s grounding tabs) better be closed or left open? Should the Frame Ground (PIN 18 FGND) be connected to the chassis ground or the signal ground (PIN 1) or left disconnected?

Thank you so much for any help and/or recommendations!

Rgds,

*m
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CF Support2

Administrator
As you have found, the grounding options for the CFAG320240CX family has a lot of options. I've attached some marked up images of these options.

From experience, we have seen that the CFAG320240CX family is tolerant of EMI / ESD when the ground / frame ground is set up. The set up we have found depends on the application. I would start with closing the frame ground and seeing how it behaves. The key is to give any noise, and ESD in particular, a nice easy path to ground that doesn't go through the controller.

Another option that some customers have done in particularly noisy environments is to add some EMI shielding to the front of the module using a conductive mesh. We have located a couple of manufacturers of conductive mesh:

http://www.seiren.com/english/fabric/p4/f.htm

This link is via a Trade Resource Company, All searches seem to link back to or refer to Seiren or A-Jin "

http://www.alibaba.com/catalog/11268298/Conductive_Mesh_Fabric.html

One distributor / manufacturer we are aware of is:

Dontech Inc.
http://www.dontechinc.com/
Phone: 215-348-5010
Fax: 215-348-9959.
 

Attachments

neonsee

New member
Thank you for the advice... .

Could you please clarify what exactly you mean by "closing the frame ground". Do you mean connecting PIN18 to the chassis ground of our system or to PIN1 / signal ground?

As the bezel can certainly catch some ESD, I guess it would be best to close JF1 and connect the mounting holes to the chassis, while leaving JF2 open. The ESD would than have a nice / low ohmic path to the earth ground of the system while not disturbing the "clean" signal ground. What would you say?

Thanks again for your help!

Rgds,

*m
 
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