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Original question:

ADC12DJ3200EVM: JESD204B Interface with KCU105

ADC12DJ3200EVM: Can LMK04828 work with Fs=3200Msps on ADC12DJ3200EVM

Joseph Xu
Prodigy 170 points
Part Number: ADC12DJ3200EVM
Other Parts Discussed in Thread: LMK04828, LMX2582, , LMK04832

Hi HSDC team,

I'm working with own hardware based on the reference design of ADC12DJ3200EVM. I've got a question that is whether the LMK04828 work with Fs=3200Msps. According to the original ADC12DJ3200EVM setting, the LMX2582 generates a 3.2GHz clock to the ADC, and also feedback another 3.2GHz to CLKin1 of LMK04828B to generate corresponding Dclk* and SDclk*.

I dump out the cfg file from ADC12DJxx00EVM GUI for "On-board, Fs=3200Msps, JMODE3", and import the cfg file into the TICS Pro, found that the setting for the LMK04828B is below:

As you can see, there is a indication in red. According to the TICS Pro, the VCO0 and VCO1 cannot work exceed 3080MHz. Under such condition, can this settings work normally? Please help me to confirm this, thanks.

Some information attached:

TICS Pro Vesion: 1.7.0.0

Build date: 09-Jan-2020

Part Version: 2017-01-11 v3.2.0

I've also attached the log file from the GUI and the same setting for TICS Pro.

adc12djxx00evm_gui_settings_log.csv

TICSpro_LMK04828.txt

Thanks.

  • 0
    TI__Mastermind 33690 points

    Hi Joseph,

    The TICS Pro message can be ignored since the internal VCOs are not used. Instead, the CLKin1 external VCO or distribution mode frequency range should be used.

    That said, the datasheet actually shows a maximum external input frequency of 3100MHz, so the 3200MHz frequency is still beyond characterized maximum frequency. Note that even though the frequency is above the characterized maximum, the LMK04828 has enough margin on the timing parameters to be able to function with 3200MHz Fin input. Electrical characteristics at 3200MHz are not guaranteed... some electrical characteristics may deviate slightly outside of the minimum/maximum ranges listed. But the device will still function and distribute the 3200MHz clocks with performance roughly comparable to 3100MHz.

    For a device which is rated to >3200MHz, you can use the LMK04832 which is p2p-compatible with LMK04828. Conceivably you could even swap the LMK04828 on the board with an LMK04832. I'm not as familiar with the ADC12DJ EVM software, but I believe it is possible to use the register programming directly from the LMK04832 TICS Pro exported hex file... the GUI display of registers may be nonsensical if programming an LMK04832, but it should still load the programming to the device.

    Regards,

  • 0 in reply to Derek Payne
    Prodigy 170 points

    Hi Derek，

    Thanks for your confirmation. Situation has been tesed. It's working.