This part is a kind of semiconductor called 3DD1555A.

Function of this product has CASE-RATED BIPOLAR TRANSISTOR.

Manufacturers : JILIN SINO

Image and pinout :

Some of the text within the PDF file :

CASE-RATED BIPOLAR TRANSISTOR FOR TYPE 3DD1555A FOR LOW FREQUENCY R 3DD1555A MAIN CHARACTERISTICS BVCBO IC VCE(sat) tf 1500 V 8A 3 V(max) 0.6 s(max) Package TO-3P(H)IS APPLICATIONS z z Horizontal deflection output for color TV. z3DD1555A RoHS NPN , FEATURES z 3DD1555A is high breakdown voltage of NPN bipolar transistor. The main process of manufacture: high voltage plane type process, triple diffused process etc, adoption of fully plastic packge. RoHS product. ORDER MESSAGE 123 EQUIVALENT CIRCUIT RBE=50 (Typ.) Order codes Marking 3DD1555A-O-A-N-D D1555A MARKING Halogen Free Package NO TO-3P(H)IS Packaging Foam Device Weight 5.50 g(typ) Trademark Part No. Year month For example 8 2008 10 10 october 200911C 1/6 R ABSOLUTE RATINGS (Tc=25 ) 3DD1555A Parameter Colle [ ... ]

3DD1555A PDF Datasheet Download