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AM6442: The EXT_REFCLK1 pin for Main domain clock input

Haiwei Zhang
Prodigy 50 points
Part Number: AM6442

Hello, I want to use the EXT_REFCLK1 pin as the clock input pin for the primary domain, can I directly connect to the 3.3V voltage reference clock source?

At the same time, I give MCU_OSC0_XI and MCU_OSC0_XO external crystal oscillator, my purpose is to make the primary domain and MCU domain clock source independent. Is it okay to do that? If so, is there anything I should pay attention to? Thank you.

  • +1
    TI__Guru 63145 points

    You can source a 3.3V clock to the EXT_REFCLK1 input as long as VDDSHV0 is powered from a 3.3V source. However, the EXT_REFCLK1 input can only be used to source a few peripheral modules. It is not able to source the entire main domain. I recommend you launch the AM64x clock tree tool and use it the develop a better understanding of the device clocking topology.

    https://dev.ti.com/sysconfig/?product=CLOCKTREE-AM6X&device=AM64x

    Regards,
    Paul

  • +1 in reply to peaves
    TI__Guru 63145 points

    I forgot to mention the IO cell associated with the EXT_REFCLK1 pin is turned off by default. Your system software would need to boot and enable the input buffer of this IO before being able to use this clock input. Your system software would also need to change each clock multiplexer of any peripheral that will use this clock source since none of them default to this clock source.

    Regards,
    Paul