Tamas Rudnai wrote:
> Couple of days ago someone else here (sorry, could not recall his name)
> said 1.0uF is not good for low drop regulators.

Huh?  There seems to be a lot of dead fish waving here today.

All LDOs that I recall reading the datasheets of require some output
capacitance for stability.  Most also specify some minimum input capacitance
because they need low input impedence.  The gotcha is some LDOs,
particularly but not limited to the cheap asian ones, require a minimum ESR
of the output cap for stability.  Unless you are doing a high volume design
where the extra $.10 matters, you should stick to a LDO that is stable down
to 0 ESR output cap.  You can get yourself into trouble with the ones that
require a minimum ESR if you don't know exactly what you're doing.  Anyone
that has to ask about decoupling here or uses rules of thumb and lore as a
substitute for real understanding need not apply.

This is one thing I like about the Microchip MCP1700 and MCP1702 LDOs.  They
are guaranteed stable with 0 ESR output caps.  This means you can (and
should) put a SMD ceramic cap right accross the output pins as close to the
LDO as possible.


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