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TMS320F28069: about analog input specification before power on

Yojiro Yane1
Intellectual 580 points
Part Number: TMS320F28069


hi all

My customer use the TMS320F28069PZT, and they have a question.

Their board has input a voltage on analog pins before power on.
  voltage : +/- 662mV max, current : +/- 0.526mA max.

Is it have the problem in above case.
They would like to know Analog pin specification. In the Datasheet is no descriptions.

Best Regards,

Yojiro

  • 0
    TI__Guru 62975 points
    Yojiro,

    The ADC pins are included in the "Input voltage" row of the Absolute Maximum Ratings table.

    Is there a series resistor on the analog pins that is limiting the current to +/- 0.526mA when +/- 662mV is applied externally?

    If it is a resistor, I think the system will be ok because the +/- 0.526mA is well under the absolute maximum rating of +/-20mA, and the voltage drop across the resistor will probably result in much less than +/- 300mV appearing on the ADC pin itself.

    -Tommy
  • 0 in reply to tlee
    Intellectual 580 points

    Tommy,

    Thank you for your quickly response.

     Is there a series resistor on the analog pins that is limiting the current to +/- 0.526mA when +/- 662mV is applied externally?

    Yes, there is a series resister 100 ohm on the analog pins. 

    Voltage across the resistor is 52mV. current into this pin 0.526mA at Vdd = 0V.

    I think that it is OK, because voltage is under the absolute maximum rating.

    I will inform them to our customer.

    Best Regards,

    Yojiro