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LMX2572: Manual Ramping in LMX2572

Ayush P
Prodigy 10 points

Part Number: LMX2572

Hi, 
I am trying to achieve Manual Ramping using LMX 2572. My interest range is from 4240 to 4250 , a 10MHz ramp whose step size is 250KHz. I am not getting any results and the data sheet is redundant on how to configure TiCS Pro to achieve a manual ramp. I am programming through SPI via FPGA. What should be my ramp_Clk and ramp_dir. 

Automatic ramp is working fine 

This is my configuration Screenshot 2025-11-19 154047.pngScreenshot 2025-11-19 153920.pngScreenshot 2025-11-19 154029.png

  • 0
    TI__Guru** 120130 points

    Hi There,

    Try:

    CAL_CLK_DIV = 0x1

    Ramp_limit_high_freq = 4260 MHz

    I will check this in the lab tomorrow.

  • 0 in reply to Noel Fung
    TI__Guru** 120130 points

    Hi There,

    There is no issue in manual ramp mode.

    Make sure you start with the default configuration.

    LD_DLY = 0.

    CAL_CLK_DIV = 1.

    My configuration file:

    e2e2572ManRamp.tcs

    Fullscreen e2e2572ManRamp.txt Download 
    R125	0x7D2288
R124	0x7C0000
R123	0x7B0000
R122	0x7A0000
R121	0x790000
R120	0x780000
R119	0x770000
R118	0x760000
R117	0x750000
R116	0x740000
R115	0x730000
R114	0x727802
R113	0x710000
R112	0x700000
R111	0x6F0000
R110	0x6E0000
R109	0x6D0000
R108	0x6C0000
R107	0x6B0000
R106	0x6A0007
R105	0x69A6A1
R104	0x682710
R103	0x673333
R102	0x663FFF
R101	0x650001
R100	0x642710
R99	0x63CCCD
R98	0x620000
R97	0x610088
R96	0x600000
R95	0x5F0000
R94	0x5E0000
R93	0x5D0000
R92	0x5C0000
R91	0x5B0000
R90	0x5A0000
R89	0x590000
R88	0x580000
R87	0x570000
R86	0x560000
R85	0x55FFE0
R84	0x540001
R83	0x530000
R82	0x520040
R81	0x510000
R80	0x500000
R79	0x4F0060
R78	0x4E0001
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	0x3E00AF
R61	0x3D00A8
R60	0x3C0000
R59	0x3B0001
R58	0x3A9001
R57	0x390020
R56	0x380000
R55	0x370000
R54	0x360000
R53	0x350000
R52	0x340421
R51	0x330080
R50	0x320080
R49	0x314180
R48	0x3003E0
R47	0x2F0300
R46	0x2E07F1
R45	0x2DCE1F
R44	0x2C12A3
R43	0x2B0001
R42	0x2A0000
R41	0x290000
R40	0x280000
R39	0x27FFFF
R38	0x26FFFF
R37	0x250205
R36	0x240035
R35	0x230004
R34	0x220010
R33	0x211E01
R32	0x2005BF
R31	0x1FC3E6
R30	0x1E18A6
R29	0x1D0000
R28	0x1C0488
R27	0x1B0002
R26	0x1A0808
R25	0x190624
R24	0x18071A
R23	0x17007C
R22	0x160001
R21	0x150409
R20	0x144848
R19	0x1327B7
R18	0x120064
R17	0x110096
R16	0x100080
R15	0x0F060E
R14	0x0E1820
R13	0x0D4000
R12	0x0C5001
R11	0x0BB028
R10	0x0A10F8
R9	0x090004
R8	0x082000
R7	0x0740B2
R6	0x06C802
R5	0x0530C8
R4	0x040A43
R3	0x030782
R2	0x020500
R1	0x010809
R0	0x00A11C

  • 0 in reply to Noel Fung
    Prodigy 10 points

    Hi,

    I tried your configurations, but could not observe the expected output. I am currently using Oscilloscope, probing the V_tune. I have one doubt, sould I toggle RampDir everytime?

    Regards,

    Ayush P

  • 0 in reply to Ayush P
    TI__Guru** 120130 points

    Hi There,

    RampDir determines the direction of frequency shift. 

    A rising edge of RampClk will change the frequency one time. Click the Clock Ramp button once in the GUI will change the frequency once.

  • 0 in reply to Noel Fung
    Prodigy 10 points

    Hi,

    As I mentioned earlier that I am using FPGA to program the LMX. On that instance how to configure the Ramp_Dir? Also I need one more suggestion on how to get a sawtooth ramp. i.e. RAMP0 is incrementing for 200us and RAMP1 is decrementing for 50us.What should be my step size in this scenario?

  • 0 in reply to Noel Fung
    Prodigy 10 points

    Also I would like to know , in your config it was ramp 0 to ramp 0 
    If I try to make it RAMP0 -> RAMP1 and RAMP1 -> RAMP0, it is not working properly.



    Please help me with this. 


  • 0 in reply to Ayush P
    Prodigy 10 points



    Hi there ,

    I have got this output. The yellow is the Vtune output. And Orange is Ramp Dir which is 50u on and off time, Green is RampClk which is 200KHz. I want my Vtune output to be more steeper. My observation is that based on how my Ramp_Dir is the Vpp changes. The ramp up should be 200us and ramp down should be 50us. I need support on how to config Ramp Dir to achieve my specs.

    Regards,
    Ayush P

  • 0 in reply to Ayush P
    TI__Guru** 120130 points

    Hi Ayush,

    in manual ramp mode, RampDir and RampClk are external signals feeding to the LMX device. You need a logic device to generate these timing signals. In register configuration, you need to program the correct RAMP_INC for each ramp. In this case, since your ramp up and ramp down time is different, RAMP_INC will be different for ramp up and ramp down. 

  • 0 in reply to Noel Fung
    Prodigy 10 points

    Hi Noel,

    Thanks for your support, I am getting the expected results. Last question, what is the maximum ramp I can generate in this LMX? Above 40MHz it is kind glitchy. If it it possible to generate at least 80MHz, it would fit more towards my application.

    Regards,
    Ayush

  • 0 in reply to Ayush P
    TI__Guru** 120130 points

    Hi Ayush,

    As you know this synthesizer has 6 VCO cores, so we need VCO calibration to select the right VCO and band for the frequency of interest. 

    We can force the VCO not to perform VCO calibration, but the tuning range is limited to approx. 50MHz. I am pretty sure that 80MHz is usually not possible.