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Review of LMK04828 Schematic

Jayden Park
Expert 1100 points
Other Parts Discussed in Thread: LMK04828, SN65LVEP11, CDCLVP1102

Hi!

Our customer will use LMK04828 device in RRH system.

So, Out customer want review of TI.

Also, I will recommend SN65LVEP11 instead of ICS85311 in 1:2 Fanout Buffer.

How about your think?

Please review attached schematic file.

 

LMK04828 Schematic.pdf
  • 0
    TI__Expert 4400 points

    You can recommend CDCLVP1102 for the 1:2 fanout buffer since it has much lower additive jitter than SN65LVEP11.

    Here are my comments on the schematics of LMK04828:

    - On outputs where LVDS signaling level is desired, it is better to configure outputs as LVDS and then use 100 ohm between P and N before AC coupling capacitors. You save more power this way. If SYSREF can be LVDS, please follow the same as above as well.

    - Use a pulldown on SYNC pin. This sets a default known state on the pin.

    - The loop filters are reversed. What is noted as PLL1 loop filter is for PLL2 and what is noted as PLL2 loop filter is for PLL1. Please correct these.

    - The power supply design is not optimal. It is better to isolate Vcc_CP2, Vcc_VCO, Vcc_PLL1, Vcc_PLL2, Vcc_DIG, Vcc_OSCin and Vcc_OSCout from rest of supplies using ferrite beads. You can group Vcc_VCO, Vcc_PLL1, Vcc_DIG using a ferrite bead (followed by an array of 10uF, 1uF, 0.01uF). You can group Vcc_PLL2, Vcc_CP2 using a ferrite bead (followed by an array of 1uF, 0.1uF, 0.01uF). You can group Vcc_OSCin and Vcc_OSCout using a ferrite bead (followed by 1uF, 0.1uF, 0.01uF). On output supplies (Vcc_CG[0-3]), please group them together and use a 1uF for each supply (total of 4). Please follow user guide for recommendations on supply network.