I am designing an Atmega based precision(upto 2 decimal places) 0-35v power supply.I designed the circuit and need a stable 5v ref.I have both REF02EP+ and MAX6126AASA50+ in hand.I have tested and found that the REF02 is giving stable 4.996v(-4 mV off) whereas the MAX6126 is getting off upto -1mv to +15mV(4.999v to 5.015v) by varying the temperature.I measured it with a Fluke 87V in MIN-MAX mode.
But from datasheet,I can see that both ICs have same tempco(3ppm/degree centigrade).Why the MAX6126 behaving strangely??Any suggestions??
Which will be the best choice for my power supply??Please give your feedback.....