Hi,
We have multiple LMK04828 devices/channels. They all would have the same settings so basically just multiple copies of the exact same LMK04828 channels. We want to synchronize the DCLK/SYSREF generation across all of these LMK04828 channels and we're looking to synchronize the driving of the SYNC/SYSREF_REQ pins so that all of these LMK04828 devices would register the SYSREF requests at the same time and thus would generate the DCLK/SYSREF pairs at the same time accordingly.
We're feeding the CLKin1 with a 125 Mhz external clock. The VCO would run at 3Ghz and DCLKs run at 1GHz. We want all LMK04828 devices to generate SYSREF pulses on that same 1Ghz DCLK outputs at the same time.
We have a couple of questions.
1) How does the SYSREF_REQ signal get registered? Is it registered internally using 125 Mhz CLKIN1 input? Also is one clock cycle long enough for the duration of this request signal?
2) If we were to match the phase of the 125Mhz CLKIN1 to make sure all LMK04828 devices see the same clock and also the same SYSREF_REQ pulse timing-wise, can we assume all of these LMK04828 devices will generate DCLK/SYSREF pairs at the same time?
Thanks for the help,
Tyler
