LMK05028: JESD204B Support?

Hello Louis,

As you are aware, the LMK05028 doesn't support JESD204B by the datasheet. Technically you could make it work for a JESD204B application but you'd have some limitations you would want to be fully aware of...
1) LMK05028 can't generate a single (or group) of SYSREF pulses. You'd be stuck with a continuous output until you turn the output off. This mode can work... if the JESD204B receiver is able to turn on/off listening for sysref so you could power down (or up) the SYSREF without concern for glitches.
2) I think it is possible to turn the output off, and keep the divider running by simply powering down the output. This means you could later re-sync if needed without restarting everything. So that's good.
3) There is no ability to adjust phase between the outputs. This means to meet the setup and hold time for the SYSREF, you'd have to completely rely on the receiver to be able to adjust, or have routed the traces just perfect so it meets the setup and hold times for SYSREF to Device clock at the receiver.
4) I'm going to leave open the possibility that I've missed something here. But I think the highest risk thing is #3 unless your receiver can do the job for you.

If you compare with the LMK0482x/32 or LMK0461x. There is the ability to generate a 1-shot SYSREF pulse. There is also the ability to make fine adjustments of the SYSREF phase to the device clock. Take this video for example: https://www.youtube.com/watch?v=9fXAMOPrRYM.

73,
Timothy