Hello,
We are planning on implementing the LTC6909 muti-phase clock in our product. However, we have multiple different LT regulators operating, and these will be connected with SYNC/PLLIN to LTC6909.
There is a section in the LTC6909 datasheet that covers the topic of start-up issues, where problems can arise if the regulator does not ignore external clock signal at start-up. The datasheet mentions that most switching regulators from LT ignore the clock input until a power good state is achieved. However, we understand that this does not apply to all LT switching regulators, and it might be necessary to utilize some sort of PGOOD common connection that enables clock IC through PH0-PH1-PH2. We would rather like to avoid such a solution.
The datasheets of the LT switching regulators do not explicitly state if the external clock signal is ignored at start-up, so we are wondering how we can determine from the datasheet if the regulator supports such operation?
We are especially interested in knowing whether the LTC3895, LT8365 and LT8331 regulators will ignore the external clock from LTC6909 at start-up.
Best regards,
Tobias