This part is a kind of semiconductor called AEO20A48-L.

Function of this product has DC-DC / Industry Standard Isolated Eighth Brick.

Manufacturers : Emerson

Image and pinout :

Some of the text within the PDF file :

Embedded Power for Business-Critical Continuity AEO/ALO Series 66/120 Watts Total Power: Up to 120 Watts Input Voltage: 48V # of Outputs: Single Rev. 09.30.08_100 AEO/ALO Series 1 of 4 Electrical Specifications Special Features Input Input ra­nge: Input surge: Input UVLO: Efficiency2: 36 - 75VDC 100V / 100ms 33-36 V (UVLO ON) 31-31 V (UVLO OFF) 93% @ 5V (typical) <0.1% vo (typical) Up to 25A for Vo < 1.8V 20mVPK-PK (typical for Vo < 2.5V) 2% typical deviation (50% to 75% Step Load) <100us settling time (typ) 130% Vo typ (autorecovery) 130% Io,max typ (autorecovery) • 2.3” x 0.9” Industry Standard 8th brick outline • Baseplate or Openframe construction • Low Ripple and Noise • Regulation to zero load • High Capacitive load start-up • Fixed Frequency Switching fo [ ... ]

AEO20A48-L PDF Datasheet Download