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LMK00306: LMK00306

Arnaud CHOPIN
Prodigy 10 points
Part Number: LMK00306

Dear,

For a project in development, we work with the ZCU102 Evaluation Kit (including Zynq UltraScale+ ZU9EG) for a demonstrator.

And to drive RF switch from 50 MHz (with Duty cycle at 50% max) to ~ 3.3MHz (with duty cycle at 3%), we use LVDS interface of FPGA.

I was looking for a buffer LVDS, with one input and several outputs, and I find LMK00306 from TI.

Several LMK00306 are used (qty = 5), to drive 15 RF switch at the same time (with a margin).

Each LMK 00306 has a synchronized LVDS signal generated by the FPGA.

For us, timings Trise and Tfall are very important. With LMK00306, 300ps for Tr and Tf, it's acceptable.

I am looking to assess the min / max delay between the slowest and the fastest of the control signals, to know the margin.

It has specification of Duty cycle (page 9 of datasheet), specififed between 45% to 55% for 50% input clock duty cycle. And Output Skew Timing on page 13.

How understand these informations, on pages 9 and 13 of LMK00306 datasheet, about "Output Clock duty cycle" and "Duty Cycle skew" ?


For a signal on input of LMK00306, What signal do I find at the output ?
With what delay ?

Thanks.

Best Regards.

Arnaud CHOPIN

Uses_Case.pdfLMK00306_Pages9and13.pdf

  • 0
    TI__Genius 10875 points

    Hi Arnaud,

    I'm not entirely following your ask. 

    The datasheet states that for an input clock with a 50% Duty Cycle, the output Duty Cycle was measured to vary between 45% and 55%. Since we only tested the LMK00306 with a 50% duty cycle, you may test how the device behaves with a 3% duty cycle using the IBIS model found here.

    Propagation delay is the time it takes the output signal to go from HIGH to LOW or LOW to HIGH.

    Output Skew refers to the propagation delay difference between 2 outputs at identical transitions (see note 18 below). It's typically measured from the rising edge of one output to the rising edge of another output.

    Part-to-Part Output Skew refers to the output skew across other LMK00306 devices. e.g. the propagation delay between CLKoutA0 on device 1 and CLKoutA1 on device 2.

    We have this apps note on how we define the timing terminology. It may provide you with further understanding.

    Regards,

    Jennifer