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ADS8361: input over voltage

Other Parts Discussed in Thread: ADS8361

What is the output behavior of the ADS8361 when the input voltage is over the range and over the AVdd.  Specifically A0+ or B0+ goes over or under the input range and exceeds the supply lines.

AVdd for us is 5V  AGND is 0 reference.   There are times our Op Amp will drive to 5.5V or -0.5V through a 1.05K to the A0+ or B0+ terminal.  I know the input diode protection will conduct and we are limiting the current through it.  What will the conversion do?  Will it output max or min or is it possible that the output will invert a sign or maybe become less that max or min?  I didn't see anything in the data sheet that addresses this.

We are on a time constraint and welcome your help ASAP.

Thanks,

-John

  • For differential Vin > Vref; output codes will be positive full scale. For differential Vin < -Vref; output codes will be negative full scale. Common mode of Vref/2 must be maintained at all times. If common mode is maintained, the converter will follow its transfer function.

    As you pointed out, protection diodes will turn on and limit the input signal voltage between -0.3V and AVDD+0.3V. This will cause increase in the current drawn from driving op-amps.
  • Thank You RahulVK.