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LP87524J-Q1: Pull up resistor selection for some pins

user6158104
Intellectual 300 points
Part Number: LP87524J-Q1

Hello,

Let me ask questions about the pull up manners of the pins.

Thank you in advance for your support.

  • 0
    TI__Genius 11020 points

    Hello,

    Answer is yes to all of your questions. 

    You can also see the checklist available here: 

    https://www.ti.com/lit/zip/snvr480

    Thanks.

    Regards,

    Tomi Koskela

  • 0 in reply to Tomi Koskela
    Intellectual 300 points

    Hi Tomi,

    Thank you very much for your quick response and the helpful check list !

    Please kindly let me double-check my understanding about the answer regarding the question No.1 and No.3.

     

    [No.1] -EN1,EN2,EN3

    We are planning NOT to use I2C for controlling the chip LP87524J-Q1. In this case, if we set EN1 as "high" at least, output voltages are set as the default setting automatically, since each register is set as default value in the power up. (Based on the datasheet, Table 3 Regulator Control ) Is my understanding correct?

    [No.3]-SCL(#5), SDA(#6)

    According to the check list you have attached, the pin#5 and #6 are directed to be ground-connected when I2C is not used.

    Could you please let me know which is better, connecting to ground or pulling-up to 3.3v via 4.7Kohm?

    Thank you in advance. 

    Best regards,

    Masayuki Nakajima

  • 0 in reply to user6158104
    TI__Genius 11020 points

    Hello Nakajima-san,

    Yes you can use the device without I2C control. Only EN1 control is needed to start the bucks with the predefined voltages with the sequencing set in the OTP memory. You can see also details about the default configuration in this technical reference manual: https://www.ti.com/lit/ug/snvu663/snvu663.pdf

    SCL/SDA can be connected to GND and since it does not need extra components it is usually easier. But if for debugging purposes you would need I2C connection to the device later on, that can be a problem in the pins are routed directly to GND. So I would recommend placing those resistors and pulling to the 3.3V VIO voltage, then you have anyway option to hook it up to some external I2C controller if needed.

    Thanks.

    Regards,

    Tomi Koskela