Hi all,

I'm tinkering with an 18F23K22 and the A/D has changed a bit from the=20
16F devices I've used previously.  This A/D can now automatically wait=20
for the holding capacitor to charge, rather than manually waiting the=20
required charge time as before.  But I'm confused how to set this.

I'm using this datasheet --=20
http://ww1.microchip.com/downloads/en/DeviceDoc/41412E.pdf

The second paragraph of 17.1.4 explains that the acquisition time will=20
be done automatically with this newer A/D, and says it can be set=20
anywhere from 2 to 20 Tad.  But 17.1.5 explains that a full 10-bit=20
conversion required 11 Tad.  So why is Tad configurable from 2 to 20? =20
IE: what would be by reasoning for setting it anything other than say 12Tad=
?

In my specific example, I'm running at 16Mhz, so from Table 17-1 I'll=20
use Fosc/16 or Fosc/32, giving me 1.0us or 2.0us Tad.  But then I set=20
Tacq to 12 Tad again, right?

Only reason I can see for the Tad adjustability is that it allows for=20
source impedances that are higher or lower than the ideal range... ???

Cheers,
-Neil.


--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.