Hi Padmanabham,
Can you give us litte more details about the power supply circuit and how you are powering the ADC?
What kind of environments (power,noise,etc) are you going to use the product?
What is the magnitude is voltage sensed by the ADC (Volts,mVolts,uVolts,etc..)?
What type of sensor are you connecting to your instrument?
Can you use a different ADC, or do you want to stick to this ADC only?

Do you want the stability only on reference voltage? then for 8bit ADC, I think TL431 will be a better choice, easily available here and cost effective.

Note:
In your User profile you have not mentioned your location, so assuming you are from India.

Bye,
Mr. Kiran V. Sutar.