[sdiy] LF398 and droop

[Tim Parkhurst]

On 5/16/07, mark verbos <mverbos at earthlink.net> wrote:
> How bad will a S&H build from an LF398 perform if a ceramic cap is
> used? I built one using a .01 ceramic and I can actually watch the
> voltage falling on the output. Is this the cap type? Am I missing
> something?
>
> Thanks,
>
> Mark
>

Hey Mark,

I've heard two things about S/H circuits:
1) Use Polystyrene or Teflon or Polypropelene caps.
2) Try to include a "guard ring" around the positive terminal of the
cap on your pcb. See the 398 data sheet for examples.
3) Clean flux off of S/H circuits, as flux residue can create a high
impedance leakage path for the charge on the cap.


Tim (heard I can't count, either) Servo
-- 
"Imagination is more important than knowledge." - Albert Einstein