Im currently working on a DC/DC board in a two rail configuration. The schematic is identical to the schematic in the datasheet for the 12V dual rail example except there is a trim poti to set the output voltage. Currently the LTC7890 gets hot while the EPC2361 GaN-FETs themself stay cool. When not enabled (RUN=0V) the circuit draws about 11mA (with INTVCC=0V) and when enabled it draws about 15mA (with INTVCC=5.5V) and the output voltage is at 2.7V. Even in Off state the high side FETs get 0.8V on their gate while the Low Side Fet gets 0V on its gate. In RUN mode the high side fet has 2.7V on its gate.
When loaded the output drops to 800mV and the high side fet now has 800mV on its gate. The gate has no short circuit to drain or source.
Do you have any ideas what could be wrong?
