Hi,
I'm using the output CLKFX of a DCM in a virtexII pro with CLKIN = 10MHz. The M factor is 27 and the D factor is 10 so that I get CLKFX = 27MHz. Since the PLL mode does not support CLKIN < 24 MHz should I still keep the feedback loop between CLK0 and CLKFB.
Thanks. Christophe.
the
Hi,
I had with the Spartan 3 DCM same problem. If you use Feedback, then input freq. can't be below ca. 24 MHz. But if you do not use Feedback, then input freq. can't be below ca. 1 MHz. Without Feedback is only problem Phase.
Tarmo Palm
Do not feed back CLK0 to CLKFB. Then your input frequency can be as low as 1 MHz, if your output frequency is above 24 MHz. So you are o.k. You do not have a defined phase relationship between input and output, but that should not be a real loss, considering the ratio of your frequencies.
10 MHz and 27 MHz coincide only once every microsecond... Peter Alfke
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