LMX2572EVM: Phase synchronization using LMX2572

Nikolaus Metzger

Prodigy 60 points

Part Number: LMX2572EVM

Dear forum members

we are phase coherent switching between two frequencies using the LMX2572EVM.

We facilitated it in software through toggling VCP_PHASE_SYNC_EN:

Green and yellow is the 100MHz clock and 100MHz signal out - phase synchronization is nicely achieved.

We were not able to facilitate this using the external pin in the following configuration:

where we input a square wave (0 to 3.4V) into the Phase Sync pin on the evaluation board. However the phase of the clock on output signal are not aligned.

My question is do we have to set a register to achieve phase synchronisation?

Thank you Nikolaus

over 2 years ago

0 Noel Fung over 2 years ago

TI__Guru* 86080 points

Hi Nikolaus,

Did you uncheck the INPIN_IGNORE bit? This bit is located at User Controls page, Phase ADJ section.

0 Nikolaus Metzger over 2 years ago in reply to Noel Fung

Prodigy 60 points

Hello Noel,

yes I tried this but it is still not working - should my signal on the Phase Sync pin be high (3.3V) all the time? Also to double check, the Phase Sync Pin is the SMA connector next to the power in?

Again this only works if I switch the VCP_PHASE_SYNC_EN.

Thank you for your help, Nikolaus

0 Noel Fung over 2 years ago in reply to Nikolaus Metzger

TI__Guru* 86080 points

Hi Nikkolaus,

Yes, pull HIGH the SYNC pin either by checking the SYNC box in TICS Pro:

Or provide a HIGH signal to the SYNC SMA connector.

Clock & timing

Clock & timing forum

LMX2572EVM: Phase synchronization using LMX2572