Voltage regulator with alternate voltage source...

Err.. unless the voltage of the switcher is identical to that of the 7805, then one device will source current, and the other will sink it. Like putting two 6V batteries in parallel, where one is fresh and the other weak. Current will flow until the potentials are equalized. But with two regulated circuits, I don't see how equality can be achieved. Not saying it's going to smoke-out, but it does seem like a wonky thing to do. On Thu, Apr 7, 2016 at 3:41 PM, wulfman <wulfman at wulfman.com> wrote: > You should be just fine. > > On 4/7/2016 1:38 PM, Bill Sudbrink wrote: > > If you have a circuit which is normally designed to > > operate with an unregulated supply, through a regulator... > > say unregulated +8 through a 7805 to a regulated +5 and > > you want to test it independent of the +8 supply, if > > you leave the unregulated rail unattached and put +5 > > switcher straight onto the regulated +5 rail, will you > > damage the 7805? Clearly the VIN is open, but the ground > > pin will still be attached. Would this push voltage > > back through and screw things up? > > > > Thanks, > > Bill S. > > > > > > > > > -- > The contents of this e-mail and any attachments are intended solely for > the use of the named > addressee(s) and may contain confidential and/or privileged information. > Any unauthorized use, > copying, disclosure, or distribution of the contents of this e-mail is > strictly prohibited by > the sender and may be unlawful. If you are not the intended recipient, > please notify the sender > immediately and delete this e-mail. > >