There is a small current (<100uA) in the internal charge pump of the MAX14912 when it is powered. The charge pump is not controlled by shutdown, so there is an instantaneous dither pulse upon powering up:
The power-up speed of the VDD power supply will affect the width of this pulse. When VDD climbs slowly, and EN = low, a dither pulse of around 300us (with/without load) can be seen at the output end of push-pull or high-side mode; if EN = high without any load, we can see an output pulse of around 6ms. The output pulse is around 300us when there is a 1kohm output load. When VDD climbs faster (24V hot-swappable power supply), and EN = high with 1kohm of output load, the output pulse will not be seen upon powering up. It is recommended that, when powering up VDD, EN should be set at low or a load should be added to the output end to reduce the output pulse.