The DAC8830 datasheet specifies 9KOhm minimum input impedance for the reference voltage input. The DAC in my application has 2.5V reference voltage and 3.0V power rail (Vdd). Per datasheet 2.5V/9KOhm = 278uA maximum current into the reference voltage input. My application is very sensitive to the overall power consumption of the circuit board.
I tested two DACs at +90 degrees C (added 5 degrees margin). Both DACs were set to 0xFFFF code. The temperature ramp-up and ramp-down rate is 0.25deg Celsius per minute. The reference input current of one of the parts is within the spec.
The reference input current of the other parts is around 450uA at the beginning of the exposure to +90 degrees C and very slowly creeps down. Four days later, reference input current reaches 250uA.
I am concerned with the initial value of the reference input current of the second part at +90 degrees C and its change over time. Is this behavior considered normal given that the test temperature exceeds the part spec of +85 deg C by 5 degrees?
Thank You
