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LMK5C33216: LMK5C33216

Part Number: LMK5C33216
Other Parts Discussed in Thread: LMK5B33216


We have the LMK5C33216 on our custom board connected to XO @ 20 MHz. I am attaching the TICS Pro file.

When we load the registers to the device, we get 156.25 MHz in all outputs except Out10 that is 3x higher (468.75)

The readback registers have the values they are supposed to have.

The same behavior for this output happens when I pick different frequencies, ZDM, have PLL activated etc .

The freq is measured using counters inside the FPGA.

What registers can I read to get the actual frequency . Anything strange that you see in TICS pro file?

Thanks so much!


  • Hello Michail,

    Interesting, I loaded the tcs file and measured all output clocks at 156.25 MHz with the EVM.

    Could you try probing with an oscilloscope?  Could there be some impedance mismatch which is causing the 3rd harmonic of 156.25 MHz to be measured?

    As a side note... the LMK5B33216 is pinout compatible with LMK5C33216, a slight change in the output format programming - but the PLL3 with the BAW operates at 2.5 GHz allowing you to get 156.25 MHz on all outputs with outstanding BAW type performance.


  • Hi Timothy,

    Thanks so much for the help. I left probing  the clocks as the last choice since the termination 201 caps were at a difficult spot. But after your confirmation I did it and indeed all clocks look as expected. I also appreciate the information about LMK5B33216 - indeed this is ideal for us and we will try to replace it if we get a hold of some of these. Thanks