Unless it's in the data sheet, don't try to use it for real. You are powering the chip through the protection diodes, so the voltage is lower than you think, and those diodes aren't meant to be turned on in normal use. It's an old trick, but it's not a good idea. On Mon, Feb 2, 2015 at 7:24 PM, David Meiklejohn wrote: > Allen Mulvey wrote: > > Sent: Tuesday, 3 February 2015 1:06 PM > > To: 'Microcontroller discussion list - Public.' > > Subject: RE: [EE] ICs working with Vdd/Vcc disconnected? > > > > This is a documented feature of the DS18B20 digital temperature sensor. > > They call it "parasite power." > > Yeah, I knew about it from 1-wire devices - but didn't know that it was a= n > "undocumented feature" of chips with separate power supply pins! > > > Cheers, > David > > > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .