This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

LMX2592: Locking Issue

Part Number: LMX2592


Tool/software:

Hello,

I am using the lmx2592 and I am using a 100 MHz external reference clock.

I am using the doubler to increase the the pfd to 200 MHz. 

I have attached the registers I am writing in the file registers.txt.

However it is only locking for certain frequencies. 2Ghz and 6.4GHz are working for example but 6GHz is not working.

If I am not using the doubler and use 100 MHz pfd everything works fine and the lmx2592 locks.

R70	0x460116
R69	0x450064
R68	0x4407BC
R67	0x4371FD
R66	0x420002
R65	0x412800
R64	0x400077
R63	0x3F0094
R62	0x3E0000
R61	0x3D0001
R60	0x3C0000
R59	0x3B0000
R58	0x3A0000
R57	0x390000
R56	0x380001
R55	0x370000
R54	0x360820
R53	0x350080
R52	0x340000
R51	0x334180
R50	0x320300
R49	0x310300
R48	0x3003FC
R47	0x2F08CE
R46	0x2E08A3
R45	0x2D0000
R44	0x2C0000
R43	0x2B0000
R42	0x2A0000
R41	0x2903E8
R40	0x280000
R39	0x278204
R38	0x26001E
R37	0x250000
R36	0x240000
R35	0x230019
R34	0x22C3EA
R33	0x212A0A
R32	0x20210A
R31	0x1F0401
R30	0x1E0034
R29	0x1D0084
R28	0x1C2924
R27	0x1B071A
R26	0x1A027C
R25	0x190000
R24	0x180509
R23	0x178842
R22	0x162300
R21	0x150064
R20	0x14012C
R19	0x130965
R18	0x1203C0
R17	0x11E114
R16	0x100037
R15	0x0F0025
R14	0x0E0CE7
R13	0x0D4000
R12	0x0C7001
R11	0x0B0018
R10	0x0A10D8
R9	0x090B02
R8	0x081084
R7	0x0728B2
R6	0x06C802
R5	0x0500C8
R4	0x041943
R3	0x031902
R2	0x020500
R1	0x010808
R0	0x002118

  • Hi Ennis,

    There is min. N divider restriction on every PLL.

    in your configuration, your N divider is too small for the MASH ORDER you have selected. Either reduce the fpd to increase N divider value or use a lower order mash, you should be able to get it lock.