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LMK03806BEVAL: LMK03806B - PLL not locked with Crystal | How to program 491.52 MHz out with 100MHz onboard crystal reference

HIMA SUNEETH PUTTA
Prodigy 70 points
Part Number: LMK03806BEVAL
Other Parts Discussed in Thread: USB2ANY, LMK03318, LMK03806

Hi there,

I am currently evaluating LMK03806B clock module using LMK03806BEval. 

I am able to program the EVM using USB2Any (although there are issues with the direct connectivity of uWire pins, I got it working with the help of this thread) and TICS Pro GUI.

I am seeing the correct CLKout (Freq & output format) as I program.

1. However, the PLL is not getting locked to the onboard crystal (100 MHz crystal on the EVM).

Please see the below snippets of my current configuration:

a) USB2ANY & EVM connectivity (as per this thread)

b) User controls (NO_SYNC's are checked because SYNC cable is not connected between USB2ANY & the EVM)

c) PLL settings

d) CLK outs (enabled only CLKout2)

2. Secondly, my application requires 491.52 MHz CLK. I am hoping to use the onboard 100MHz Crystal (of the EVM) to achieve this Clk freq (491.52 MHz). I am not able to program the VCO freq and other parameters (PLL_N, PLL_R, PDF etc.,) that can yield this freq (if at all it is possible?)

Could anyone please help me with the above two queries?

Many thanks

Hima

  • 0
    TI__Genius 12941 points

    Hi Hima, 
    1. If you're using a XTAL for your reference signal, 

    Enable the EN_PLL_XTAL crystal option in the user controls tab. 

    On page 42 of the EVM user guide their is an USB2ANY<uWire adapter guide. If you have this adapter connect the header pins in the correct positions so you may communicate/connect to the device via USB. 

    2. LMK03806B has an integer PLL thus the device is not be capable of generating the 491.52 MHz output clock frequency you require. 

    I recommend LMK03318 instead. 

    Regards, 

    Vicente 

  • 0 in reply to vicente flores prado
    Prodigy 70 points

    Hi Vicente,

    Thanks a lot for your response.

    1. Regarding PLL lock - I did try with the EN_PLL_XTAL option checked. I still didn't see the PLL lock Disappointed

    I did read in previous threads that TICS Pro has some issues with this device (LMK03806). Are there any known issues?

    2. I am using a USB2ANY interface adapter (link)

    I've connected USB2ANY to my PC with USB cable. On USB2ANY, the J4 header is connected to the EVM using the 10-pin cable.

    (However, the 10-pin cable didn't work straightaway, looks like the pins are flipped or something like that. So, I broke the 10-pin cable and connected uWire pins of USB2ANY to the uWire header of the EVM )

    I believe TICs Pro is able to communicate with the EVM using USB2ANY correctly, as I am seeing the effect of changing the CLK divider, output format (LVDS, LVPECL) etc. on a  Scope.

    2. Ohh, I see! I thought according to LMK03806's datasheet, fractional clock outputs are also possible?!

    Please correct me if I interpreted it incorrectly.

    on page.18 of the LMK03806 datasheet

    Many thanks

    Hima

  • 0 in reply to HIMA SUNEETH PUTTA
    TI__Genius 12941 points

    Hi Hima, 
    1. Oh no :(
    The device itself doesn't have any issues rather the parts profile is a bit picky about the entries. 
    When you enter a value in any of the fields, sometimes the corresponding fields do not get updated which causes locking issue. For example: N divider value=12, many times you change this value and the PLL_N_CAL value under User controls does not match. A debug step i recommend is to check all fields matching or being update accordingly.

    2. Does loading the EVM default result in the correct output frequencies being seen on the scope? If that is the case then yes, you're communicating with the device successfully. 
    3. LMK03806B only have integer output dividers unfortunately. A fractional output is possible but you need to divide the VCO frequency by an integer value that results in 491.52 MHz. The issue here is that this device cannot generate the VCO frequency required. 

    Regards, 

    Vicente 

  • 0 in reply to vicente flores prado
    Prodigy 70 points

    Hi Vicente,

    2. When I load default mode config "100 MHz XO/TCXO Reference" - I see the following configurations and the outcome on a Scope.

    (CLKout6 and CLKout 8 are enabled with 1200MHz and 200MHz respectively)

    I had to check NO_SYNC for CLKout 6 & 8 to see their output on the scope (else they are disabled - note that I have not connected SYNC wire between USB2ANY & EVM - I have connected only four uWire pins)

    Outputs on Scope. CH-2 is CLKout8 (200 MHz LVDS) and CH-3 is CLKout6 (1200 MHz LVDS)

    And, when I change the CLK divider - I see the CLK freqs changing on the Scope. 

    So, I believe the USB2ANY is communicating with the EVM successfully. Please confirm.

    3. In your comment on fractional CLK frequencies - you meant 491.52 MHz can be achieved if VCO freq is divided by a fractional clock divider, correct?

    thanks a lot

    Hima

  • 0 in reply to vicente flores prado
    Prodigy 70 points

    Hi Vicente,

    Regarding whether or not LMK03806B can generate 491.52MHz CLKout - Can we generate the closest CLKout by using external references like those shown below?

    Are the VCO freqs shown feasible as per LMK03806B?

    Many thanks,

    Hima

  • 0 in reply to HIMA SUNEETH PUTTA
    TI__Genius 12941 points

    Hi Hima, 
    A 98.304 MHz input can generate a 491.52 MHz output. 

    LMK03806B_491.52MHz_OUT.tcs

    Regards, 

    Vicente 

  • 0 in reply to vicente flores prado
    Prodigy 70 points

    Hi Vicente,

    Thanks a lot for the confirmation and for providing the .tcs file.

    Just have a quick question before I test out the .tcs file.

    How do I verify the lock detection? Is it D3 or D4 LED that I need to look at?

    Looks like EVM's user guide and the part's (LMK03806B) datasheet contradict each other in terms of verifying the lock detection.

    on page.10 of EVM's user guide - it says D4 (which is connected to pin-27, Readback) shows the lock detection.

    But, in the pin configuration (datasheet of LMK03806B) - it looks like pin-33 is the one that indicates the lock detection.

    Could you please clarify this for me?

    Many thanks

    Hima

  • 0 in reply to HIMA SUNEETH PUTTA
    TI__Genius 12941 points

    Hi Hima, 
    The pin that indicates LD is pin 33 (LED D3).

    Regards. 

    Vicente 

  • 0 in reply to vicente flores prado
    Prodigy 70 points

    Hi Vicente,

    Thank you very much for anwering my queries promptly. 

    I'm now able to generate CLKout with required frequency and PLL also gets locked!

    As a next stpe, I am looking to automate the TICS-Pro configuration using Labview. Would you kindly be able to provide support in this regard?

    I've got example VI's from this thread - https://e2e.ti.com/support/clock-timing-group/clock-and-timing/f/clock-timing-forum/684376/ticspro-sw-lmx2594evm-and-ticspro-sw-possible-to-use-scripts-python-perl-etc-to-do-some-automation

    I'd like to know the following: 

       1. What are the connections to be made between EVM & the Labview PC (GPIB etc.,)

       2. Are there VI's that show how to select a device (in my case: LMK03806B) and to load a '.tcs' file onto TICS-PRO?

    Many thanks again for your support

    Hima

  • 0 in reply to HIMA SUNEETH PUTTA
    TI__Genius 12941 points

    Hi Hima, 

    I am glad to read you're able to get the PLL to lock! Slight smile

    1. The LMK03806BEVM only has a uWire interface Connector that connects to USB2ANY. USB2ANY supports the following communication interfaces: 

    I understand LabView can communicate via I2C and SPI. 

    You can learn more about USB2ANY with the following appnote: https://www.ti.com/lit/ug/snau228/snau228.pdf?ts=1666368466749&ref_url=https%253A%252F%252Fwww.google.com%252F

    2. We currently don't have any VIs that show how to select a device but from the "TicsPRO automation with Labview" doc that was inside the thread you linked above, I can see that it is possible. 

    Regards, 

    Vicente