[sdiy] Power Supply Start-up Issues

[René Schmitz]

On 26.08.2020 22:02, John Speth via Synth-diy wrote:
>
>> The cure for each is the same. Reduce start up current. And the 
>> easiest way to do that is reduce the decoupling capacitance on 
>> modules. I've seen modules with a couple of 220uF connected to their 
>> power headers. Perhaps it's best not to use any more than 4u7 per 
>> rail per module, unless series resistors are used.
>>
> This design is as old as three terminal regulators, probably older. 
> I've seen some similar designs with small series resistors on each 
> regulator output. I always assumed they were there to limit inrush 
> current. The tradeoff will be too large (too much voltage drop, 
> negating the regulation that the regulator provides) vs. too low 
> (having insufficient effect on inrush current).
>

If you want to delimit the current with resistors, then place them ahead 
of the regulators.


Best,

  René


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