AVR-Chat

Jim Wagner said:
>
> Tantalum caps are nice because of small size and low ESR.
> ESR isn't much of a requirement in linear regulators. But,
> they cost more, have limited voltages and values, and have
> a tendancy to destroy themselves (ie, explode or burst into
> flames) if not in a current-limited circuit. Thus, putting
> them in a place where they directly "see" battery power is
> asking for trouble. It is less of an issue on the output
> since the regulator, itself, provides current limiting.
> They also tend to be more attractive on the output side
> since the larger value is needed there. A general rule
> commonly used by designers is to specify a tantalum voltage
> rating that is about 2X the actual working voltage.

We have typically used MLC (multilayer ceramics) on switching supplies
with some additional electrolytics if needed for bulk capacitance.  The
MLC capacitors have an extremely low ESR and can be more effective than
tantalum capacitors.  Also ceramic capacitors are more tolerant of applied
voltages and are often tested to 4X or more of rated value at the factory.

Mike