XP Power has small green 180W AC-DC power supplies
They are medically approved, have average active mode efficiency of 93% and a no load power consumption of under 0.5W.
Convection cooled rating is 120W and the full Output power needs 10CFM of forced airflow.
Called ECP180they measure 2 x 4 x 1 inches.
Nominal outputs are 12, 15, 24, 28, 36 and 48 VDC.