I have an application for the TPS65251 in which I am generating 3.3V on Buck 1 and 1.8V and 1.2V on Buck 2 & 3. My power sequencing requirements are:
1.) 1.2V
2.) 1.8V & 3.3V
I noticed the datasheet explains to use capacitors on ENx pins to delay the start-up of each converter (1.6ms per nF). I had planned to cascade the Vout from each converter into the next converter's EN pin. However, the V(IH) threshold for the EN pins is >1.2V which would be my first supply up. I'm afraid this approach will not work. Is using capacitors the correct way to control power-up sequencing?
My next dilemma is power-down sequence in the reverse order. Any thoughts on how to achieve this?
Thanks,
Brian
