Hi Joe:
If the 150 V DC is generated from the 3.7 V DC, then a fault between the two circuits will cause the 150 V DC to stop and become 3.7 V DC. The Law of Conservation of Energy. There is no way the 150 V can cause the 3.7 V to increase! Therefore, there is no need to isolate the 150 V DC from the 3.7 V. Any single fault will result in "SELV." ***** Single-fault testing is applied to any component in the series circuit from a body part touching the USB common to the 150 V DC to the 300 Hz to the touch-screen to the body finger. (All measurements referenced to the USB common.) Merry Christmas! Rich - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.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...@radiusnorth.net> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
