I am using HMC7044 in my customised design. I have disabled PLL1 and using only PLL2. I am feeding a 100MHz clock from external crystal to HMC7044 through OSCIN pin. But PLL2 is not locking. What may be the reason.
I have checked the 100MHz clock at OSCIN pin and it looks fine.
I am checking 0x7D (bit 0) register for PLL2 lock status. I am reading 0x02 as readback data of this register.
I have another HMC7044 on the same board where PLL2 is locking and reading back 0x7D register gives 0x13 (bit 0=1) . This shows that PLL2 is locking on 2nd HMC7044.
Please let me know what may be the reasons for PLL2 not locking. Any help is much appreciated.