LMK04828BEVM: PLL1 and PLL2

Hello,

Have you changed the Loop filter components on your EVM? If you are using the EVM, and replaced the Crytek 122.99 MHz VCXO with your own 160 MHz VCXO then you will need to update the Loop Filter components (capacitors & resistors) on the board in order to achieve lock.  You can use our PLLatinumSim tool in order to calculate the correct values to use.  Here is a helpful e2e which shows how to configure PLLatinum Sim in order to adjust your PLL loop filter components.  

Another note,  you should always maximize your phase detector frequency for both PLLs.  This will definitely improve performance.  I have attached a ticspro config file with higher phase detector frequencies.

Regards,

Will

lcliff_try_updated.tcs

Hi, 

This didn't solve my issues. Pll1 is still not locked. I redesigned a clock. Please have a look. I tried PLLitinum as well. 

4666.bishnu_LMK04828B_rfsoc4x2default_try.tcs

Bishnu,

I will get back to you by the end of the week.

Regards,

Will

Bishnu,

Your config looks like it should lock. I am guessing your problem lies in your loop filter.  A few questions:

• How are you determining the lock status of the PLL's?
• Could you please tell me your Loop Filter component values? C1, C2, and R2 for PLL1 and C1, C2, and R2 for PLL2?
• Could you please share the VCXO 160MHz you are using?  The Kvco and VCO capacitance values can effect the loop filter values.

Regards,

Will

Bishnu,

In your other thread you mentioned that you are able to achieve lock with a different configuration?  Can you share the .tcs file for that configuration and tell me about that setup?

Regards,

Will

Hello William ,

There are my filesa and configuration.

RFSOC 4x2 board has LEDs to determine whether it is locked or not. In my case, PLL2 is locked. PLL1 led is not on.

 I used PLLatinum Sim and found PLL1 is vcx0 = 160,  c1 = 100 ng, c2 = 680 nf, and R2 = 39 K ohm KVco is 0.0025 Mhz/V,  PLL2 VCO1 = 3000 MHz,  c1 = 0.047 nf, c2 = 3.9nf, Kvco = 20 MHz/v, R2 = 0.62 K ohm. 

The file where i have PLL2 locked (LED turned on) and PLL1  not locked (LED didn't glow) is the same file as mentioned above. 

Thank you.

8244.bishnu_LMK04828B_rfsoc4x2default_try.tcsbishnu_LMK04828B_rfsoc4x2default_try1.tcs