But I don’t understand how the internal step down temp (55C) can be the same for both the scenarios above -
max output external temp 56C at step down
low output external temp 38C at step down

It doesn’t make sense to me :question:

I’m guessing the temp sensor is facing up on the driver and therefore measuring air temp within the cavity. Had I turned the driver upside down then the temp sensor would be closer the heatsink and have a different reaction time to the above cases :?: maybe