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TPS1H000-Q1: MCU I/O Protection

Andy Snawerdt
Intellectual 2300 points
Part Number: TPS1H000-Q1

Hello Team,

I'm trying to understand the need for series resistance protection on the DIAG_EN & IN pins of this device. The datasheet specifies these for FAULT, IN, and DIAG_EN:

Given "FAULT" is an open-drain output, I see how if the MCU GPIO was accidently programmed as an output, this could cause a short-to-gnd condition on the MCU I/O, hence the series resistance limits the current in this scenario protecting the MCU GPIO from damage. However, I'm not seeing how this logic applies to the DIAG_EN and IN pins given that they are inputs to our device. Any clarification here is much appreciated!

Regards,

Andy

  • +1
    TI__Mastermind 32650 points

    Hi Andy,

    This is just a series protection resistor to protect the MCU from any situation where current can unintentionally flow either into or output the node.

    A good example of this is in the event of a reverse polarity condition and current flows into the GND pin of the device, it is possible for current to flow out of the I/O pins through internal ESD cells. This would have been reduced to small values by the GND network but the series resistance provide further protection to the MCU.

    Using these series resistors are not required for the operation of the device but it is just another line of defense.

    Thanks,

    Shreyas