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Honored Contributor
Honored Contributor48Mhz XTAL or 12MHz thru PLL x4?
My circuit already has a crystal that outputs a 12MHz signal to the MCU, which then PLL it to 48MHz internally for use. Since I also need 48MHz on the MAX 10 10M02 FPGA, I was wondering why not simpl...
Altera_ForumHonored Contributor
Honored ContributorAh thanks, that's good to know. Routing a 4-pin active crystal oscillator's 12MHz output to both the FPGA and the MCU was indeed what I meant.
About the FPGA's PLL: Does sending a 12MHz clock signal to the FPGA and using the PLL to multiply it by 4 for internal use has any disadvantage versus sending a signal already at 48MHz to the FPGA? As far as I've read, using a PLL to multiply the input clock only uses the PLL subsystem as far as resources, and I didn't see anything that would suggest: "If you can input a signal already at the frequency you need, do it instead of using a PLL".
