Dear all,
I am using the circuit below to sense the switch press.



The conditions to be detected are;

SW1 SW2
0 0
0 1
1 0
1 1

On calculations iam getting the following:

SW1 SW2 ADC In
0 0 2.00V
0 1 1.25V
1 0 2.5 V
1 1 1.66V

But when i simulated using Pspice (monticarlo 100runs) iam getting the ADC values ovelapped for two different states.

My supply voltage tolerance is 5% and i fixed the resistor tolerance to 1%.


Also the Max input voltage to ADC should not be more than 2.5V since the internal reference voltage to ADC(successive approximation) is fixed to 2.56V DC (to avoid supply voltage tolerance).

I have to do Monticarlo analysis for 10000 runs.

Iam using this type of sensing due to limited Microcontroller pins.

I would like to have some suggestions to achieve this.

Sorry for posting it in Main forum.

I request the Moderator if it could be shifted to Chat Forum.

Thanks!

Suresh.