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LP87702-Q1: PIN 22 usage

Part Number: LP87702-Q1

Dear team,

PIN22 is CLKIN/GPO2/WD_DIS multiplexed. When GPO2_SEL=0, PIN22 is CLKIN function. When GPO2_SEL=1, PIN22 is GPO2 function. Then how to set WD_DIS function?

If WD_DIS_CTRL=1 and GPO2_SEL=0, then pin22 have two functions at the same time, right? 

Thanks & Best Regards,


  • Hi Sherry,

    WD_DIS function requires GPO2_SEL to be set to CLKIN and WD_DIS_CTRL set to 1. CLKIN then controls the watchdog, high=disabled and low=enabled.

    To use watchdog disable function and external clock the watchdog must be enabled and locked during the watchdog long window. In other words, CLKIN pin must be low and WD_LOCK is written to 1. After that the external clock can be started.

    Best regards,

    Samuli Piispanen

  • Hi Samuli,

    Thanks for your reply!

    I notice the default register value GPO-SEL2=0 which means this pin is CLKIN. If I don't use the external clock and use the internal clock. How do I connect this, floating or connect to GND?

    Thanks & Best Regards,


  • Hi, If in the default OTP configuration CLKIN_PD=1 is selected, then there is already 500Kohm pull down active and in this case, you can leave this pin open, else, it can be connected to GND externally.