Ken, First, the disclaimer - I'm not an I-Safe expert but my company does make some I-Safe products so I have some knowledge that I've absorbed here. So take that into account when evaluating this advice...
I believe the important factor is energy, not voltage, for explosive atmosphere use. Typically products need significant modifications to the devices depending on their classification. Since these modifications typically result in tons of extra components being added to the system to achieve a fault tolerant reduction in the possible energy in any one area of the circuit, I'd be sure the mods are in place before doing too much work on the EMC evaluation. To your question at hand, some of the newer devices have LED backlighting which should not require an inverter to boost to high voltages like other backlight systems. I'd check with your client to determine what system is used. Otherwise, the newer inverters I've seen in our products are much quieter than they used to be but this is something to keep your eye on since these are essentially switching supplies and can create broadband noise. Best Regards, -Dave David Heald EMC Engineer | Worldwide Regulatory Compliance tel: +1.631.738.5373 fax: +1.631.738.5520 From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Ken Javor Sent: Monday, December 18, 2006 10:37 AM To: emc-p...@ieee.org Subject: PDA back lighting potential Forum Members, I am evaluating a PDA-like device for EMI/explosive atmosphere usage. The device has what appears to be an LCD type display, which means it has back-lighting. While the device runs off 4.2 Vdc batteries, which are deemed a safe potential, I expect that the back-light potential is at a much higher level, and that getting from 4.2 Vdc to that higher potential can be potentially noisy from an EMI point-of-view. Any commentary/experience to share? Thank you, Ken Javor - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ________________________________________________________________________ This email has been scanned for computer viruses. ________________________________________________________________________ This email has been scanned for computer viruses. - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to emc-p...@ieee.org Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas emcp...@ptcnh.net Mike Cantwell mcantw...@ieee.org For policy questions, send mail to: Jim Bacher: j.bac...@ieee.org David Heald: emc-p...@daveheald.com All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
