[sdiy] SSM2164 last time buys

[Neil Johnson]

Hi Oscar,

>>I'd still look into adding a series
>> resistor with a
>> local decoupling capacitor as  I don't think we yet
>> know how long a
>> worst-case 2164 can survive on its own without the -ve
>> rail.
>
> A question: How does work the decoupling capacitor on there?

Ideally you want the V+ pin to see a low impedance voltage source at
AC frequencies of interest.  If we just put a series resistor in the
line then we increase the source impedance and that could affect the
AC operation of the 2164 - it might, for example, reduce the slew rate
of the output.  So adding a decoupling capacitor after the series
resistor, directly across V+ to GND, reduces the source impedance and
mostly restores normal operation.  The size of capacitor will depend
on the exact application, lowest operating frequency and the value of
the series protection resistor.

Cheers,
Neil
-- 
http://www.njohnson.co.uk