For Information Technology: only if the device that ultimately supplies the power has installation instructions that states Conditions of Acceptability for meeting requirements of an LPS; and if there is supporting test data in the CBTR, agency FUS report, etc.
Also, the USB 2.0 (see section 7) standard requires that connected devices limit their power consumption, and that the bus be able to detect a long rise-time caused by overload. But, the USB spec does not address I.T. safety considerations of the host as an LPS. luck, Brian > -----Original Message----- > From: Carpentier Kristiaan [mailto:[email protected]] > Sent: Friday, December 17, 2004 3:23 AM > To: ieee pstc list > Subject: USB interface Limited Power source ? > > Hi group, > > The USB standard 1.1 or 2.0 defines that a USB host device > must have an overcurrent protection " for safety reasons". > If the aggregate current exceeds a preset value, which is 5.0 > A, then the over-current protection circuit shall remove or > reduces power to the attached devices. > > The above definition looks quite similar to the requirements > of LPS in IEC60950-1 but the wording LPS is not explicitely > mentionned in the USB spec. > > Q: Can I assume that a USB interface is LPS ? Is there any > other evidence available to support this view ? > > Thanks, > Kris 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 [email protected] Instructions: http://listserv.ieee.org/listserv/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
