[sdiy] SMD part availability, manufacture

John Luciani jluciani at gmail.com
Thu Nov 13 01:59:24 CET 2008


On Wed, Nov 12, 2008 at 7:31 PM, Seb Francis <seb at burnit.co.uk> wrote:
>
> For the power supply regulators, I've been looking at low dropout ICs and
> these seem pretty cool.  Am I really understanding it right that they can
> work with a output-input of down to like 0.2V.  This would mean only a tiny
> amount of heat dissipation so no need for any heatsinking.  Are there any
> disadvantages to these compared to standard linear regulators which need
> typically 2.5V output-input differential?

Be careful when calculating the power dissipation. You need to take the ripple
voltage into account. The trough may be at 0.2V but the peak could be much
higher. The big LDO advantage is that you can size your filter caps a
lot smaller
since your ripple voltage can be 2.5V larger.

> And good that SMD headers are easily available, although I feel a bit wary
> of using them for connections that might get plugged and unplugged a lot.
>  Since I'm sure many people would be happy wiring all panel controls,
> inputs, etc. direct to the board, perhaps I don't need to bother with
> headers.  Can just have 0.1" pitch holes and leave it up to people what they
> do with them.

There is quite a bit of surface area in the SMD header solder joints. I would be
surprised if there is a problem.

I do agree that the 0.1" pitch holes is probably a better solution. If someone
wants the header/receptacle they have the choice.

(* jcl *)

-- 
http://www.luciani.org



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