DT_Analog & 12F1822 internal voltage reference

[Darrel Taylor]

I don't think the enhanced cores were available yet when I wrote that page.
The older chips had a minimum TAD of 1.6uS, but the newer ones have a minimum TAD of 1.0uS.

So you could use the values in that table, but they will be off by 1 division from "Optimal" settings.

If you look in the A/D section of the 1822 datasheet, you should see this table ...
I've marked the best setting at each oscillator freq. in red.
Put the matching ADCS bits into the ADCON1 register bits 4-6. DEFINE ADC_CLOCK does not have any effect on the enhanced core devices.



The FRC clock is an internal RC oscillator that is separate from the main internal oscillator (FOSC).
It continues running even when the PIC is put to SLEEP.
It can be used at any OSC. But the actual TAD period can be anywhere from 1.0 - 6.0uS.