elektryk
Advanced Member level 4
max110 adc
I am designing precision adc based on maxim max110 chip. Almost everything is ok (I know there is a bug that lockup chip, but this is not this problem). I have powered chip with +/-5V and reference voltage +/- 1.2V from two lm385. Based on max110 datasheet the input voltage range bound to full digital scale (between all 1 and all 0, forget about overvoltage pin) is from Vref- to Vref+, but in my circuit is much greater then reference, whole binary range sometime is twice greater then reference voltage (depends of configuration of ADC). I know there is something like internal calibration of ADC, but after executing 3 step process (and executing normal conversion, ~NOP=1) there is no change in measurement. The transmision is OK, all bits change in direct order.
I need a fast clue, I have few days to provide finished device.
I am designing precision adc based on maxim max110 chip. Almost everything is ok (I know there is a bug that lockup chip, but this is not this problem). I have powered chip with +/-5V and reference voltage +/- 1.2V from two lm385. Based on max110 datasheet the input voltage range bound to full digital scale (between all 1 and all 0, forget about overvoltage pin) is from Vref- to Vref+, but in my circuit is much greater then reference, whole binary range sometime is twice greater then reference voltage (depends of configuration of ADC). I know there is something like internal calibration of ADC, but after executing 3 step process (and executing normal conversion, ~NOP=1) there is no change in measurement. The transmision is OK, all bits change in direct order.
I need a fast clue, I have few days to provide finished device.