Hi Team,
I wanted to verify the startup operation of the TPS40090-Q1. According to the engineer i am working with he is seeing the following start up behavior, which in fact is not documented in the datasheet:
- When EN pin goes high the IC starts up in hiccup (7 SS ramp cycles) mode occasionally.
I’m not sure it’s a feature or bug, but it’s slightly inconvenient for us, since it messes up our power sequence a bit.
(In our design we don’t use the internal BP5 regulator, but we provide 5V directly instead. That 5V supply is present before EN is asserted.) - We are using it in 2-Phase configuration, but soft-start and shutdown ramps are always generated with only phase #1 active.
Likewise, I’m also unsure whether it’s a feature or bug, but datasheet does not mention such behavior to be exist.
During this time the only load is a ~25Ohm bleeder resistance on this 0.85V rail. It seems that after EN goes high the device starts in hiccup mode.
