I am investigating using an LTC6908 in an application with multiple power converters. In this application, it would run at a nominal frequency of 560 kHz (504 kHz to 616 kHz with spreading). I am hoping to confirm that all the converters that will be sync'd to it are able to do so -- in particular, I'm concerned about behavior with a spread spectrum clock into a converter that might, for example, have an undocumented PLL. The following converters are used in the design:
Can you confirm that all of these devices are expected to be able to synchronize to an LTC6908?
All of these converters do have an input for synchronization and are compatible with the LTC6908. In normal, steady state clocking, there should be no issues at all. Using the spread spectrum FM does require…
Yes, all are compatible with LTC6908
All of these converters do have an input for synchronization and are compatible with the LTC6908. In normal, steady state clocking, there should be no issues at all. Using the spread spectrum FM does require some thought at the system level though. If the switcher has too narrow of a closed loop bandwidth, then it will not be able to properly track the spread spectrum frequency modulation and output ripple may be worse than with a steady clock. The LTC6908 has three modulation rate settings to allow it to work with virtually all switchers. To know all implications for sure you would need to get feedback from the expert on each of the individual parts though.
Thank you, Doug. I'll come back with per-part questions (and more details -- capacitor-set frequencies, LTC6908 frequency and modulation rate, etc) once the design approaches finalization.