We use the HMC7044, and we want to use (multi)cycle slipping for clock phase adjustment.
To test the cycle slipping, I program a low output frequency (i.e. 1MHz), and enable cycle slipping. On some of the channels this works, on some it doesn't. I have tried multi-cycle slipping, and single-cycle slipping, but still the same.
I have found the issue on our project board, but verified this on the HMC7044 eval board (changed VCXO from 122MHz to 100MHz).
Some settings, in this case cycle slipping does not work for all channels:
With these settings, cycle slipping does work properly:
With these settings, cycle slipping does also work properly:
Does anyone else see this issue?
Is there a setting I am missing?
It seems like increasing N2 from 12 to 24 gets it working. Is there a limitation on N2 divider for cycle slip to work? I chose highest PFD2 frequency for best jitter performance.
If I limit N2 values to a minimum value, does this solve the problem for all other frequencies? What would be the minimum value for N2?
Any feedback is appreciated.
I configured the HMC7044 Evaluation Board with on board VCXO (122.88 MHz).
R2 Divider: 1
N2 Divider: 12
VCO Selection : High
(The configuration setup that you say problematic.)
VCO frequency with this configuration is 2949.12 MHz.
I set all the output channels with divide by 2048 which provides 1.44 MHz output frequency ( around your low frequency).
But I was able to use cycle slip in each channel taking CLK0 output as base.
Can you state in which channels you can't use the slip property?
Thank you for your quick reply.
Channel 2 and 3 will slip, Channel 0 and 1 won't. I'm not sure about the other channels.
I am travelling now; I will provide the eval board settings file next week when I'm back at the office.
Please find attached the demoboard setup file for my failing config. This is created using HMC7044 demoboard software version 1.0.
RefClk = CLKIN1, 312.5MHz.
Again: My VCXO is 100MHz. With 122.88MHz you will need different divider settings, which may or may not give different results...HMC7044_setup.zip
I tried your setup file with HMC7044 eval board.
I suggest you to disable multislip for the channels that you use, also send reseed request each time you change the slip value.