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ADS1248: Protection circuit for analog input pin

Takumi Suzuki1
Mastermind 8610 points
Part Number: ADS1248

Hello,

Will you tell me the reference circuits to protect analog input pin?

And please advice me the appropriate diode to protect ?

Because the absolute max specification is from "AVSS-0.3" to "AVDD+0.3", "0.3V" seems to be smaller than general diode Vf (around 0.5V).

I have a little bit problem...your advice would be very appreciate.

Best Regards,

  • 0
    TI__Guru* 97465 points
    Takumi-san,


    We don't have any reference circuits for input protection. Many will use a combination of series resistance to limit the input current and Schottky diodes to shunt the current to the supplies. The Schottky diodes have a fast turn-on and lower forward voltage. I've seen the BAV199 and BAS70 used for this purpose.

    People have also used certain TVS diodes for input protection, however, these have much higher leakage than the Schottky diodes. In ratiometric RTD measurements, this leakage contributes to a gain error. For TVS diodes, this is likely too high of an error, for the Schottky diodes, this may be tolerable.

    If you have a specific problem, can you describe it in more detail? I would like to see a schematic and the settings of the device.


    Joseph Wu
  • 0 in reply to Joseph Wu
    Mastermind 8610 points
    Hi Joseph-san,
    Thanks so much !
    Your advice would be very helpful for me, thanks.
    Best Regards,