Yep, a linear regulator will cook with a BBB attached. Assuming the BBB consumes 1A, then you will dissipate (25v - 5v) * 1A = 20Watts. This regulator cannot handle that power dissipation and will die. Better to use a switching regulator which has an efficiency of around 90% or better.
Regards, John > On Feb 19, 2016, at 5:15 PM, Rizalino Antonio de Guzman > <rizalinodeguz...@gmail.com> wrote: > > given that my source voltage is 25V, i assumed that i should scale up this > resistor. ill give that a try next time. Thank you > > Rizalino de Guzman > > On Feb 19, 2016, at 6:06 PM, Bill Pretty <bill.pre...@xplornet.com > <mailto:bill.pre...@xplornet.com>> wrote: > >> Looking at your schematic, I believe that 1K is too large a value. It should >> be about 240 ohms and R2 should be scaled accordingly. It could be that the >> LM317 is taking too long to stabilize. You will notice that the application >> circuit provided by the data sheet uses a 240 ohm resistor. >> >> From: beagleboard@googlegroups.com <mailto:beagleboard@googlegroups.com> >> [mailto:beagleboard@googlegroups.com <mailto:beagleboard@googlegroups.com>] >> On Behalf Of Rizalino de Guzman >> Sent: Friday, February 19, 2016 7:06 PM >> To: BeagleBoard >> Subject: [beagleboard] Custom Power Supply >> >> Hello, >> I am currently trying to build a power supply based on an LM317 to provide >> different voltage outputs, powered by a single voltage source. One of the >> loads is a Beaglebone Black. I'm curious as to why my beaglebone black does >> not turn on even when my p/s output is a steady 5V (give or take. my >> simulations show 4.6V while my actual circuit produces around 5.3V). I'm >> attaching a schematic of my LM317 power supply. When I hook up the >> beaglebone on a DC power supply, it turns on. Any help would be >> appreciated. Thanks! >> -- >> For more options, visit http://beagleboard.org/discuss >> <http://beagleboard.org/discuss> >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to beagleboard+unsubscr...@googlegroups.com >> <mailto:beagleboard+unsubscr...@googlegroups.com>. >> For more options, visit https://groups.google.com/d/optout >> <https://groups.google.com/d/optout>. >> >> -- >> For more options, visit http://beagleboard.org/discuss >> <http://beagleboard.org/discuss> >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to beagleboard+unsubscr...@googlegroups.com >> <mailto:beagleboard+unsubscr...@googlegroups.com>. >> For more options, visit https://groups.google.com/d/optout >> <https://groups.google.com/d/optout>. > > -- > For more options, visit http://beagleboard.org/discuss > <http://beagleboard.org/discuss> > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to beagleboard+unsubscr...@googlegroups.com > <mailto:beagleboard+unsubscr...@googlegroups.com>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
