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SM72445: SM72445 Datasheet NC4 Resistor Selection

luminous
Intellectual 590 points
Part Number: SM72445

Good day

I note the datasheet calls for a pull up resistor value of 60.4K to the 5V line. The Solar Magic design uses a 174K pull up resistor.

There is no explanation in the datasheet regarding the function of NC4 (pin 23) so it makes for difficult understanding as to why a specific value of 60.4K is the recommended vlaue.

Anyone have any idea of why this is so?

Kind regards

Nick

  • 0
    TI__Mastermind 46905 points

    Hi Nick,

    unfortunately, we can't find detail about the method to select this resistor.

    but i think this pin is used for some internal function. please follow the suggestion of the datasheet and use a 60.4K resistor or closed to this value.

  • 0 in reply to Jasper Li
    Intellectual 590 points

    Hi Jasper

    Thank you for the reply. It is a little unfortunate that the documentation does not cover aspects such as this and my previous thread relating to the Register values. The documentation is a tad scant. Interestingly the Solar Magic design uses a 174K resistor and no explanation given.

    Thanks again for your efforts.

    Kind regards

    Nick

  • 0 in reply to luminous
    TI__Mastermind 46905 points

    Hi Nick,

    yes. i guess there is no specific function in this pin but just need to pull high. but I can't find more document detailing the function of this pin.

    thanks for your understanding. let me know if there is further question. I will try to help although i may not know more than you.