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ADS131e08 Input Protection Consideration

Poh Kok Keng
Genius 5112 points
Other Parts Discussed in Thread: ADS131E08, ADS130E08

hi,

I am a newbies to ADC design. Would like to know if I used ADS131e08, do I need D1 to D16 diode for Input Protection Consideration? I saw the ADS131e08 evaluation kit at  ADS130E08 User's Guide (Rev. A) (sbau202a.pdf)  http://www.ti.com/litv/pdf/sbau202a, these diode are no mount. Does it means Input Protection is not required for ADC inputs to this IC?

Rgds,
kpk

  • 0
    TI__Mastermind 38745 points
    Hello kpk,

    The EVM is a great example of a functional design, but I would not necessarily say it fits every application. If you look at page 2 of the datasheet for the ADS130E08 (SBAS574A), you will find the table of Absolute Maximums. This table will tell you the maximum allowable voltages and currents on the chip. Essentially you will need to design a protection circuit if you expect the stimuli to EVER exceed the amounts listed there in the listed conditions. In your application, do you think voltages or currents at the chip will ever exceed these values?

    Regards,
    Brian Pisani
  • 0 in reply to Brian Pisani
    Genius 5112 points

    Hi Brain,

     

    In page 2 of datasheet in absolute max rating it indicates ESD protection upto 500v/1kV. Can you confirm if this protection also applies to Analog Inputs?

     

    If the Analog Inputs can indeed handle ESD voltages then definitely there are internal diodes.

     

    If user touches our tester test ports then we are concerned that ADC Input may be damaged by ESD if there is not protection. It is easy to add external protection diodes but we are concerned that even few nA of leakage current from protection diodes will interfere with the measurement accuracy.

     

    Rgds,

    kpk

  • 0 in reply to Poh Kok Keng
    TI__Mastermind 38745 points
    Hello kpk,

    Yes that does include the inputs, but please understand that the ESD specifications are done under a very specific set of circumstances. The table specifies the exact test that is performed as it relates to widely recognized testing standards. Any scenario that is not provided for in that test cannot be covered by TI's performance warranty.

    Regards,
    Brian