Microchip PIC18F2550 ADC Sampling Rate

From the Microchip PIC18F2550 datasheet (2009 version),

Minimum acquisition time, Tacq (pg 270) = 2.45us

A full 10-bit conversion takes 11 A/D cycles and each A/D cycle (table 28-29, pg 405) is specified at a minimum of 0.8us. Thus, the fastest conversion time is (11x0.8us) 8.8us

Total time = 2.45us+8.8us=11.25us

When a conversion is completed, the A/D converter should wait for three conversion periods before it can start on a new conversion. This gives 3 x 0.8us = 2.4us

Best possible minimum conversion time = 11.25us + 2.4us=13.65us.

Ignoring the software overheads, 1/13.65us = 73.26Sps=73.26 KSps (Kilo Samples per second)

Reference from Textbook 'Advanced PIC Projects in C by Dogan Ibrahim'