SD16 problem on MSP430F2013

What does "heavily" mean in numbers? Do you have the recommended 100nF (at least) capacitor at VREF for noise suppression?

The capacitor is connnected.

If the adc inital value is 2100, It will change to 1400 value without external input over time

So you mean without having ANYTHING connected to the pin? If so, then that is normal because the pin is floating with high impedance and it's charge changes over time caused by your environment. Never leave high impedance pins floating (except you want exactly that). When working with an ADC, normally the connected sensor gives a defined potential to the pin. If you have high impedance digital inputs, then you use pull-ups/downs to give a defined potential to the pin.

Dennis

Differential linear output type hall sensor is connected at P1.4 and P1.5.

Every few mili-seconds, ADC read sensor value.

And It does not have any changes in sensor.

ADC value is not chagnes in a few minutes.

But ADC value is many changed as time passes in several boards.

I think that there is a problem in the chip.

Can you tell the type of sensor? And maybe add a schematic of your circuit?