I am working on C8051F120, I am getting a problem in ADC value.
When I am working on Internal Oscillator (24.5 MHz), my PLL Setting makes SYSCLK as 98 MHZ. My Reference is provided from external source (3.0V). when I read 1.5V value on any channel, I get 2048 (which is correct). But when I change the Oscillator to an external one (25MHz), my SYSCLK becomes 100MHz. with all the same settings and no change in the code, my ADC starts reading it as 2080 instead of 2048. I had tried reducing SAR Clock value and also tried increasing the Settling time by providing a much bigger delay but the result is unchanged.
Had anybody encountered such a problem ?