Mauricio Jancic wrote:
> Hi,
> 	I have a question. When should one consider choosing a switching
> power supply over a standard AC/DC + CAP + Voltage regulator?
> 

> 	I would like to know why should I want to or consider to change to a
> switching power supply... is it usually more expensive, right?

1. Where does the power come from?
If it comes from a limited source such as a battery, you may want to 
maximize power delivery so even when the battery drops low, a switcher 
can boost it back up.  But if the circuit is power by AC mains, then a 
transformer/linear regulator is often all that's needed.

2. Where does the power go?
If a large portion goes into heating your linear voltage regulator, then 
a switcher might make sense.

3. Do you need absolutely the lowest amount of power supply noise? 
Switchers generally make more noise than linears. You really should test 
this theory first with your circuits however.  I have seen plenty of 
sensitive analog circuits run from switchers with no problems.

4. Expense?  Depends on how much power you are dealing with and how you 
will remove heat.  In a linear supply that generates a lot of heat, you 
may need large heat sinks, fans, etc.  These are not free of course. 
With so many switcher chips on the market, switchers don't have to be 
expensive.  Plus, you can make your own with stuff like the PIC10F222, 
especially for low power designs.

Good luck!
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