I opted for the LM317 design due to the adjustable feature, since im supplying 3.3, 5, 12 and possibly 18V. we're controlling multiple solenoids, stepper motors, various sensors and multiple BBB on one system. i was thinking designing the p/s in a parallel manner where i have multiple LM317s connected to a single source (ie. battery), output different voltages and connected to the appropriate loads. any recommendations on how to approach this problem would be appreciated.
Rizalino de Guzman > On Feb 19, 2016, at 7:11 PM, Graham <gra...@flex-radio.com> wrote: > > The BBB requires a very stable supply. The spec is 5.0 Volts plus/minus 0.25 > Volts under all loads, none to maximum. If the supply, as viewed at the BBB > PMC, goes above 5.5 or below 4.6 for even a few milliseconds, the PMC will go > into protective shutdown. Put a scope on the power leads and make sure your > supply can stay inside the specifications, while the load is jumping around. > --- Graham > > == > >> On Friday, February 19, 2016 at 8:42:12 PM UTC-6, john3909 wrote: >> 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 >>> <rizalino...@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....@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: beagl...@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 >>>> --- >>>> 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...@googlegroups.com. >>>> For more options, visit 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...@googlegroups.com. >>>> For more options, visit 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...@googlegroups.com. >>> For more options, visit 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. -- 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.
