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ADS831 overload operation

Have a customer who is concerned about driving their signal into the ADC and exceeding the input requirements, either from common mode or amplitude. Can you provide me with some info on how the part handles overload conditions and how fast it recovers and also what would happen if the device common mode voltages drifted?

  • Hi,

    The common-mode voltage must be 2.5v with +/-100mv. It is applied to both internal and external reference mode. The input full scale range is 2 x (REFT-REFB), and max full scale input range is 2Vpp, this is applied for both internal reference mode and external reference mode. The data sheet has error on page 10 about this. This device has no over range indication output pin, the data bus will be all 1s for input > +FS and all 0s for input < -FS. The over range recovery time is less than a clock period which means any previous input over range does not affect next data (confirmed this from the designer years ago). However, the analog input must meet the max rating spec to avoid device damage. When common-mode voltage is over the spec range it will degrade the performance of ADC, for example SNR, SFDR, DNL, etc. to out of the spec, worst case the device fails to its function.