At 12:34 PM 1/7/97 -0800, you wrote:
>>Just out of curiosity, how long does the Supercap (47 uF) stay charged
>>when the motor isn't running?
>>
>
>I never really timed it, but definitely at least a minute or so before the
>chip locks up. With a 1 mA load, a 47000uf cap should take 47 seconds to
>lose one volt, but supercaps are weird, and seem to have a large amount of
>self-discharge above about 4 volts.

Uh...the internal series resistance (ESR) starts to rise real fast as
the cap discharges, resulting in a high voltage drop, resulting in lower
output voltage.

The way to get the most energy out of the supercap is to charge it
up to the full rate voltage (5.5V) and then feed that into a switching
voltage regulator.


KR