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ADS7924: Analog input voltage?

Part Number: ADS7924

In the abs max table of the datasheet, the abs max is listed as 300mV.

Should this be ADD + 300mV instead?

It appears the input shave both GND and VDD diodes, correct?

In addition, any risk in have bias applied to input pins while unpowered?  Forward biasing clamp diodes is one clear risk.  Anything beyond that?

  • Hello,

    Yes, there is an error in the "Analog Input Voltage" line of the abs max table.  As you suspected the proper range is:  (GND-0.3V) to (AVDD+0.3V).

    Based on the specifications we would infer that there are ESD cells from the input to both supply and GND.  The current through these diodes should never exceed the +/-10mA ratings in the table and if the event is expected to occur regularly we recommend limiting the current to much lower levels.

    If voltage is applied to the inputs while AVDD is floating, AVDD will self-power from the input voltage and the AVDD pin will be at roughly a diode drop below the input voltage. If the AVDD pin has a low-impedance to GND while it's unpowered then the input voltage will cause the diode to conduct and the current needs to be limited to <10mA.