Other Parts Discussed in Thread: TPS54233
I am seeing a curious phenomenon in a circuit that uses a TPS54332 as the main regulator for a 6V rail, but which is backed up with a 5.5V LDO regulator (since the TPS54332 did not want to operate at 100% duty / pass-through mode). When the output rail is already at 5.5V the ENable threshold seems to move upwards - eg with 1.701V on the ENable pin, the TSP54332 still does not turn on, despite the typical ENable threshold being 1.25V and worst case 1.35V as per datasheet.
Is this expected behaviour from the part or should it still try to start up at 1.25V ENable voltage ?
If it is expected, then is there some documentation / design information which can be used to predict the actual ENable threshold ?
Best regards,
Patrick Herborn.