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LMX2595EVM: Lock time issue

Nicolas Lezaud
Prodigy 40 points
Part Number: LMX2595EVM
Other Parts Discussed in Thread: LMX2595, LMX2594

Hi TI-Experts,

I am dealing with some lock time issue with the EVM LMX2595.

If I shfit the frequency from

10475MHz to 10525MHz (PFD = 200MHz, Frac Mode) --> Lock Time = 20us

9975MHz to 10025MHz (PFD = 200MHz, Frac mode) --> lock time = 120ms

 


I try different sets up :

9960MHz to 10020MHz (PFD = 20MHz, Int mode) ---> lock time = 20us

9975MHz to 10025MHz (PFD = 50MHz, Frac mode) --> lock time = 75us

9999MHz to 10001MHz (PFD = 200MHz, Frac mode) --> lock time = 1s

For each configuration I write the registers with the TICS Pro interface

- I configure the PLL (frequency, PFD_DLY, quick cal EN = 1,...)

- Export the register map with TICS PRO and save the file

- Same procedure for another frequency

- Import the register map file with a different frequency on TIC PRO

- Write all register on TICS PRO and measure the lock time

I attached the register maps for 9975MHz and 10025MHz

Fullscreen 9975_HexRegisterValues.txt Download 
R112	0x700000
R111	0x6F0000
R110	0x6E0000
R109	0x6D0000
R108	0x6C0000
R107	0x6B0000
R106	0x6A0000
R105	0x690021
R104	0x680000
R103	0x670000
R102	0x660000
R101	0x650011
R100	0x640000
R99	0x630000
R98	0x620000
R97	0x610888
R96	0x600000
R95	0x5F0000
R94	0x5E0000
R93	0x5D0000
R92	0x5C0000
R91	0x5B0000
R90	0x5A0000
R89	0x590000
R88	0x580000
R87	0x570000
R86	0x560000
R85	0x550000
R84	0x540000
R83	0x530000
R82	0x520000
R81	0x510000
R80	0x500000
R79	0x4F0000
R78	0x4E026F
R77	0x4D0000
R76	0x4C000C
R75	0x4B0800
R74	0x4A0000
R73	0x49003F
R72	0x480001
R71	0x470081
R70	0x46C350
R69	0x450000
R68	0x4403E8
R67	0x430000
R66	0x4201F4
R65	0x410000
R64	0x401388
R63	0x3F0000
R62	0x3E0322
R61	0x3D00A8
R60	0x3C0000
R59	0x3B0001
R58	0x3A8001
R57	0x390020
R56	0x380000
R55	0x370000
R54	0x360000
R53	0x350000
R52	0x340820
R51	0x330080
R50	0x320000
R49	0x314180
R48	0x300300
R47	0x2F0300
R46	0x2E07FD
R45	0x2DC8DF
R44	0x2C1F62
R43	0x2B00AF
R42	0x2A0000
R41	0x290000
R40	0x280000
R39	0x2700C8
R38	0x260000
R37	0x250204
R36	0x240031
R35	0x230004
R34	0x220000
R33	0x211E21
R32	0x200393
R31	0x1F43EC
R30	0x1E318C
R29	0x1D318C
R28	0x1C0488
R27	0x1B0002
R26	0x1A0DB0
R25	0x190C2B
R24	0x18071A
R23	0x17007C
R22	0x160001
R21	0x150401
R20	0x14D848
R19	0x1327B7
R18	0x120064
R17	0x1100FA
R16	0x100080
R15	0x0F064F
R14	0x0E1E70
R13	0x0D4000
R12	0x0C5001
R11	0x0B0018
R10	0x0A10D8
R9	0x091604
R8	0x082000
R7	0x0740B2
R6	0x06C802
R5	0x0500C8
R4	0x040A43
R3	0x030642
R2	0x020500
R1	0x010808
R0	0x00251C

Fullscreen 10025_HexRegisterValues.txt Download 
R112	0x700000
R111	0x6F0000
R110	0x6E0000
R109	0x6D0000
R108	0x6C0000
R107	0x6B0000
R106	0x6A0000
R105	0x690021
R104	0x680000
R103	0x670000
R102	0x660000
R101	0x650011
R100	0x640000
R99	0x630000
R98	0x620000
R97	0x610888
R96	0x600000
R95	0x5F0000
R94	0x5E0000
R93	0x5D0000
R92	0x5C0000
R91	0x5B0000
R90	0x5A0000
R89	0x590000
R88	0x580000
R87	0x570000
R86	0x560000
R85	0x550000
R84	0x540000
R83	0x530000
R82	0x520000
R81	0x510000
R80	0x500000
R79	0x4F0000
R78	0x4E026F
R77	0x4D0000
R76	0x4C000C
R75	0x4B0800
R74	0x4A0000
R73	0x49003F
R72	0x480001
R71	0x470081
R70	0x46C350
R69	0x450000
R68	0x4403E8
R67	0x430000
R66	0x4201F4
R65	0x410000
R64	0x401388
R63	0x3F0000
R62	0x3E0322
R61	0x3D00A8
R60	0x3C0000
R59	0x3B0001
R58	0x3A8001
R57	0x390020
R56	0x380000
R55	0x370000
R54	0x360000
R53	0x350000
R52	0x340820
R51	0x330080
R50	0x320000
R49	0x314180
R48	0x300300
R47	0x2F0300
R46	0x2E07FD
R45	0x2DC8DF
R44	0x2C1F62
R43	0x2B0019
R42	0x2A0000
R41	0x290000
R40	0x280000
R39	0x2700C8
R38	0x260000
R37	0x250304
R36	0x240032
R35	0x230004
R34	0x220000
R33	0x211E21
R32	0x200393
R31	0x1F43EC
R30	0x1E318C
R29	0x1D318C
R28	0x1C0488
R27	0x1B0002
R26	0x1A0DB0
R25	0x190C2B
R24	0x18071A
R23	0x17007C
R22	0x160001
R21	0x150401
R20	0x14D848
R19	0x1327B7
R18	0x120064
R17	0x1100FA
R16	0x100080
R15	0x0F064F
R14	0x0E1E70
R13	0x0D4000
R12	0x0C5001
R11	0x0B0018
R10	0x0A10D8
R9	0x091604
R8	0x082000
R7	0x0740B2
R6	0x06C802
R5	0x0500C8
R4	0x040A43
R3	0x030642
R2	0x020500
R1	0x010808
R0	0x00251C

Thanks for your help,

Nicolas

  • 0
    TI__Mastermind 28001 points

    Nicolas,

    I looked at the 10025 MHz file and I think that this lock time has nothing to do with the LMX2594, but rather with the TICSPro write speed.

    In the first case, you are changing an integer channel, which requires only one register write.

    In the slower cases, it involves switching to fractional channels, which requires multiplie register writes.  

    Now it may be the case that the lock time for the LMX2595 is blazing fast, but the write speed for the TICSPro interface is painfully slow (in the kHz range).   In other words, if you want to measure any meaningful kind of lock time, you need to get a word generator that can write much faster. 

    If you are interested in measuring the true VCO calibration time due to our device (but NOT  SPI write time or analog settle time of the PLL), you can set the lock detect to "VCO calibration Status" and set LD_DLY=0.

    Regards,

    Dean