On Thu, 16 Apr 2009 09:02:28 -0400, you wrote:

>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.

Whearas the MCP1701 does specify a min ESR of 0R1 - min ESR requirements are not all that common but
something you do need to watch for, and not something that you'd necessarily expect if you'd not
previously read a lot of regulator datasheets..!

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