[sdiy] Best way to get a +3.3V rail from +15V?

Tim Ressel timr at circuitabbey.com
Thu Mar 7 22:24:12 CET 2013


That is the solution I would have gone with. the 125KHz switching speed keeps the inductor low and the noise above the audio range. The only caveat is layout. If your not careful with the ground loops you can make lots of radio noise or even make the beast misbehave. Since we are not concerned with getting a CE mark, it'll probably be fine.


Tim Ressel
Circuit Abbey
503-750-9331
timr at circuitabbey.com




>________________________________
> From: Jim Credland <jim at cernproductions.com>
>To: synth-diy at dropmix.xs4all.nl 
>Sent: Thursday, March 7, 2013 12:13 PM
>Subject: Re: [sdiy] Best way to get a +3.3V rail from +15V?
> 
>I've been using a MAX5033 switching regulator on a tiny PCB to get a 5V
>rail and then an LDO part on the module itself to get the 3.3V out.  The
>MAX thing was a piece of cake and seems remarkably low-noise.  
>
>What I'd really like to do is convert the -12V rail which is under used
>in the synth though to the +5V rail.  I'm sure it's possible but even
>thinking about the problem turns my head upside down.  Do I use two
>parallel step up converters? 
>
>On Thu, Mar 7, 2013, at 03:40 PM, Scott Gravenhorst wrote:
>> 
>> I'm wondering about using another regulator between +15 and +3.3.  Maybe
>> a +8v.  I would think
>> that the heat dissapation should be less for the +3.3 regulator.  Some
>> heat might also be expected
>> on the +8v reg.  It's either that or a power resistor as previously
>> mentioned.
>> 
>> -- ScottG
>> ________________________________________________________________________
>> -- Scott Gravenhorst
>> -- FPGA MIDI Synth Info: jovianpyx.dyndns.org:8080/public/FPGA_synth/
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>
>
>-- 
>  Jim Credland
>  jim at cernproductions.com
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