[SI-LIST] Re: Power Supply
- From: steve weir <weirsp@xxxxxxxxxx>
- To: bmgman@xxxxxxxxxx, mahesh@xxxxxxxxxx
- Date: Thu, 11 Mar 2004 21:50:02 -0800
Mike, he never said one way or another whether he wanted an SMPS isolated
or otherwise. I read his message as he just doesn't want to pay for a
commercial converter.
For about $2.00 we can build a non-isolated 12W forward
converter. Isolating it, depending on the performance desired only adds
about $1.00. A 36W heatsink is going to make packaging a linear solution
prohibitive.
Regards,
Steve.
At 11:34 PM 3/11/2004 -0600, Mike Brown wrote:
>Mahesh,
>
>this sounds like it could be a case of "save money at any cost". You
>are going to burn 48 watts of 48 volt power to deliver 12 watts of load
>power. Those 36 watts are not free. A DC Converter at 75% efficiency
>(and I know that you can do better than that!) burns 16 watts from 48
>volts. So if the converter costs less than 20 watts of 48 volt power
>delivery, it is actually saving money.
>
>This is overly simplistic, since the 48 volt power may already be paid
>for - hence virtually "free".
>
>However, the 20 watt difference will impact the temperature in your box,
>and the cooling impact may not be free.
>
>There may be regulatory pressure to isolate the 48 volts from the 12
>volt side for safety reasons, in which case you have no choice but an
>isolated converter.
>
>Regards
>
>Mike
>
>Mahesh Linge wrote:
>
> > Hi Grp,
> >
> > Can Any one tell me the solution for Power supply design for 48 volt to 12
> > volt(1 Amp).I am looking for a descrete solution.I dont want to use a DC-DC
> > converter in this design due to cost constraints.
> >
> > Hope some one from group will come up with better solution.
> >
> > Thanks in advance.
> >
> > Mahesh
> >
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