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ALM2403-Q1: Series Diode in datasheet 8.2.2.1

Mingkang Song
Intellectual 820 points
Part Number: ALM2403-Q1

Datasheet 8.2.2.1

This diode is to prevent the input voltage from exceeding the supply voltage, right? Can I remove it? Please explain it in detail, thanks!

(better if you could explain from a schematic perspective.)

  • 0
    TI__Guru 51796 points

    HI Mingkang,

    This is a Schottky blocking diode to protect the rest of the circuitry during a fault where the output of the ALM2403-Q1 is shorted to a higher battery voltage (18V battery)  than the op-amp supply.  Please see the Output Fault Protection figure below:

    For more detailed information, please review the Application Report "Overvoltage Protection of Resolver-Based Circuits".  This application report covers in great detail several schemes that can be employed at the board level under various circuit conditions to prevent damage resulting from the accidental shorts in automotive resolver applications.

    Thank You and Regards,

    Luis

  • 0 in reply to Luis Chioye
    TI__Intellectual 820 points

    Thanks for the reply.

    We are currently using a single cell battery normally and will not exceed 18V when fully charged. My supply voltage is also higher than 18 V in the worst case, and the ALM2403-Q1 has a Vs tolerance of 24 V, so can I not use this SD2?

    Another question is, for short-circuit testing, I only need to short the output to 16V/9V, so can I not use this SD2?

    Thanks

  • 0 in reply to Mingkang Song
    TI__Guru 51796 points

    Hi Mingkang,

    This blocking diode is required for applications where the supplies used to power the ALM2403-Q1 and other ICs, are sub-regulated voltage supply below the battery voltage. In essence, the blocking diodes protect the rest of of the ICs and supply circuitry.

    You are much more familiar with your application requirements than I am, and as you have mentioned, if in your application, the output may only be shorted to 16V/9V potential, while the ALM2403-Q1 is powered with a voltage supply higher than 18V, then there is no need for the blocking diode.

    Thank you and Best Regards,

    Luis