You need to specify the current requirement for each voltage. Regards, John
> On Feb 19, 2016, at 8:03 PM, Rizalino Antonio de Guzman > <[email protected]> wrote: > > 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 <[email protected] > <mailto:[email protected]>> 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 >>> <[email protected] <javascript:>> 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 <[email protected] >>> <javascript:>> 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: [email protected] <javascript:> >>>> [mailto:[email protected] <javascript:>] 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 [email protected] <javascript:>. >>>> 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 [email protected] <javascript:>. >>>> 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 [email protected] <javascript:>. >>> 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 [email protected] >> <mailto:[email protected]>. >> 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 [email protected] > <mailto:[email protected]>. > 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. 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