Atmel did not provide to much data for the included analog comparator.
As I very often used it, I had to discover my self the important features.
There are not SFRs associates with the at982051/4051 derivatives.
The output of the comparator is connected to P3.6 port.
The positive input is P1.0 and the negative input is P1.1
The output P3.6 can only be read by software – no interrupt associate with.
The two inputs have not internal pull-up resistors so they are floating.
The input range signal is rail-to rail ( gnd to VCC )
The input offset is about 20 mV for VCC=5V ( cf. to the datasheet).
There is not hystheresis for the inputs.
As for the settling time, there is a mystery.
I only guarantee the comparator is fast enough as I read the P3.6 port
at 24 MHz clock ( 0.5 uS cycle) in the fastest way and the read data was correct.
You can use the inputs as analog and digital simultaneously
.I used this internal comparator for implementing an 8 bits ADC with PWM ( like delta-sigma ) for audio signals and it worked well at this resolution.



Cristian