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DM6435 crystal

Eric Bryan
Expert 1045 points

The datasheet lists the crystal as 27MHz typical but no min/max.  I've seen 25MHz used without issue.   In my application it would be advantageous to use a 24MHz crystal. 

What is the range of acceptable values for this component?  What affect if any does this have on the proper capacitor values?

 

Eric Bryan

 

  • 0
    TI__Mastermind 41665 points

    Eric Bryan said:
    The datasheet lists the crystal as 27MHz typical but no min/max.  I've seen 25MHz used without issue.   In my application it would be advantageous to use a 24MHz crystal. 

    In general the 27MHz crystal is recommended/used because it allows for the same clock to be used to drive a standard analog video output (i.e. NTSC/PAL). Other crystal options are certainly possible however you may not be able to generate a valid analog video output with them.

    Eric Bryan said:
    What is the range of acceptable values for this component? 

    This is actually defined in table 6-15 and table 6-16 of the datasheet, the MXI/CLKIN signal can be between 20 and 30 MHz, I agree that this is less clear from table 6-13.

    Eric Bryan said:
    What affect if any does this have on the proper capacitor values?

    The capacitor values will really depend on the particular crystal you are using (not necessarily directly related to frequency), you should refer to your crystal's documentation or your crystal manufacturer, though as mentioned in the datasheet a typical value is 10pF.