How do you SYNC the L5991, it being a "slave"

[Flyback]

Hi,
We are using the L5991 PWM controller and want to SYNC it (its a slave).
Does SYNC'ing need a short pulse, or would a pulse as long as half of the switching period be OK?

Page 8 and 9 speak of it , but are not clear.
L5991 datasheet

L5991 - STMicroelectronics

L5991 - Current Mode PWM, L5991AD13TR, L5991D, L5991AD, L5991D013TR, STMicroelectronics

www.st.com

 

[ronsimpson]

Page 8 shows several examples. Usually there is a master and slave(s). I have sync(ed) PWM to other clocks to get all power switching to happen at the same time.

 

[Flyback]

Thanks, page 8 says the SYNC pin is "edge triggered"...but page 9 suggests that the SYNC pin being taken high, takes down the gate drive output, for as long as the SYNC pulse is high.......these details contradict each other

 

[ronsimpson]

I have not synced this part.
Another part, Sync=1=off time. If Sync=1 time is less than the Off Time, then the PWM operates like normal. But if Sync=1 for more than the "Off Time" then the sync pin extends the off time until Sync=0.
I do not know enough about this part.
My guess is that Sync edge resets the oscillator. and Sync=1 forces "off time".