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AD9548 manual mode test

Question asked by srikanth on Feb 1, 2013
Latest reply on Mar 22, 2013 by srikanth

Hi,

I am using the AD9548 PLL for 1pps synchronization.

Requirements:

o/p=89.6MHz,

i/p reference=1pps

sys clk external vco=38.4MHz,

fs set for 960MHz

 

Initially i tested in free running mode with out any reference i/p by setting FTW and i got 89.6MHz.

Later i loaded profile registers and test the status it showed both frequency and phase were not locked.  And also the status register shows that the PLL is in free run mode even if i set for manual mode, What would be the reason and how to make it lock?

As per the data sheet if the pll is set for manual mode the tuning control gets i/p from digital loop filter, which in free run mode case gets from FTW. So what i under stand is in manual mode FTW is not required and so i made it 0, but i could not get any o/p with this iteration. Is my under standing correct? Is FTW required even in manual mode?

 

Please refer the register settings file

 

Regards

Srikanth

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