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LMX2820: unable to reach target 4.441GHz

Art Mecina
Genius 16655 points
Part Number: LMX2820

Hello Guys,

Good day.

Our customer is using LMX2820 PLL. He is trying to configure 4.4416GHz from 100MHz reference. But only 4.4GHz is getting at output. He is 416KHz short of the target. What may be the reason? Below is the schematic.

Thanks and regards,

Art

  • 0
    TI__Guru** 108130 points

    Hi Art,

    Please provide the software configuration, preferably in TICS Pro format, thanks.

  • 0 in reply to Noel Fung
    TI__Genius 16655 points

    Hello Noel,

    Customer provided his PLL configuration file. Is this what you are looking for?

    Fullscreen LMX2820-REGISTER VALUES.txt Download 
    R122	0x7A0000
R121	0x790000
R120	0x780000
R119	0x770000
R118	0x760000
R117	0x750000
R116	0x740000
R115	0x730000
R114	0x720000
R113	0x710000
R112	0x70FFFF
R111	0x6F0000
R110	0x6E001F
R109	0x6D0000
R108	0x6C0000
R107	0x6B0000
R106	0x6A0000
R105	0x69000A
R104	0x680014
R103	0x670014
R102	0x660028
R101	0x6503E8
R100	0x640533
R99	0x6319B9
R98	0x621C80
R97	0x610000
R96	0x6017F8
R95	0x5F0000
R94	0x5E0000
R93	0x5D1000
R92	0x5C0000
R91	0x5B0000
R90	0x5A0000
R89	0x590000
R88	0x5803FF
R87	0x57FF00
R86	0x560040
R85	0x550000
R84	0x540040
R83	0x530F00
R82	0x520000
R81	0x510000
R80	0x5001C0
R79	0x4F011E
R78	0x4E0000
R77	0x4D0608
R76	0x4C0000
R75	0x4B0000
R74	0x4A0000
R73	0x490000
R72	0x480000
R71	0x470000
R70	0x46000E
R69	0x450011
R68	0x440020
R67	0x431000
R66	0x42003F
R65	0x410000
R64	0x404080
R63	0x3FC350
R62	0x3E0000
R61	0x3D03E8
R60	0x3C01F4
R59	0x3B1388
R58	0x3A0000
R57	0x390001
R56	0x380001
R55	0x370002
R54	0x360000
R53	0x350000
R52	0x340000
R51	0x33203F
R50	0x320080
R49	0x310000
R48	0x304180
R47	0x2F0300
R46	0x2E0300
R45	0x2D3D71
R44	0x2CD70A
R43	0x2B0348
R42	0x2A0000
R41	0x290000
R40	0x280000
R39	0x2703E8
R38	0x260000
R37	0x250500
R36	0x240058
R35	0x232100
R34	0x220010
R33	0x210000
R32	0x201001
R31	0x1F0401
R30	0x1EB18C
R29	0x1D318C
R28	0x1C0639
R27	0x1B8001
R26	0x1A0DB0
R25	0x190624
R24	0x180E34
R23	0x171102
R22	0x16E2BF
R21	0x151C64
R20	0x14272C
R19	0x132120
R18	0x120000
R17	0x1115C0
R16	0x10171C
R15	0x0F2001
R14	0x0E3001
R13	0x0D0038
R12	0x0C0408
R11	0x0B0602
R10	0x0A0000
R9	0x090005
R8	0x08C802
R7	0x070000
R6	0x060A43
R5	0x050032
R4	0x044204
R3	0x030041
R2	0x0281F4
R1	0x0157A0
R0	0x006470

    Thanks and regards,

    Art

  • 0 in reply to Art Mecina
    TI__Guru** 108130 points

    Hi Art,

    Their configuration is set for 4.442GHz. Except for FCAL_HPFD_ADJ, other register settings look fine to me and I don't see a reason why it is not able to lock to 4.4416GHz.

    Given fpd = 100MHz, FCAL_HPFD_ADJ should be set to 0x0h.