• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 21 subscribers
  • Views 318 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

LMK04828: LMK04828's clk outs

dea ayd
Prodigy 40 points
Part Number: LMK04828
Other Parts Discussed in Thread: TSW14J57EVM, ADC12DJ3200EVM

Hi,

I'am currently working on a data capture system for a multiscale communications system. ADC12DJ3200EVM and TSW14J57EVM boards are more than enough for capturing desired analog signal for the project which is around 1.5 GHz sine-gaussian. On the other hand, I have an external circuit that needs to be clocked by ADC12DJ3200EVM. I want to use internal clocking solutions provided by LMK04828, there won't be any external VCO. ADC has 2 ports for DCLKOUT10P and DCLKOUT10N which are driven by LMK04828, J23 and J24. I can get a 1.5GHz clock pulse from those ports with proper divider configuration on ADC GUI but do we know the exact amplitudes of the pulses? The datasheet says "3.15-V to 3.45-V Operation".

Regards,

Dea

  • 0
    TI__Mastermind 33730 points

    Dea,

    At 1.5GHz, assuming LVPECL format as is standard for the EVM, I would expect the actual amplitude to be much lower than 3.3V nominal, maybe 600mV at each pin or 1200mV Vod. LMK04828 output amplitude begins to degrade significantly above 800MHz. I don't have exact numbers, and it's hard to give you exact numbers, because this will in some ways be a function of the cable length, the load capacitance, the dielectric losses at 1.5GHz etc. I wouldn't expect more than 800mV to 1000mV amplitude per pin (1600mV to 2000mV Vod) worst case, since this is nominal LVPECL spec.

    Regards,

    Derek Payne