View bdx53-54 datasheet:

BDX53A/53B/53C BDX54B/54C COMPLEMENTARY SILICON POWER DARLINGTON TRANSISTORS BDX53B, BDX53C, BDX54B AND BDX54C ARE SGS-THOMSON PREFERRED SALESTYPES APPLICATIONS AUDIO AMPLIFIERS LINEAR AND SWITCHING INDUSTRIAL 3 2 EQUIPMENT 1 TO-220 DESCRIPTION The BDX53A, BDX53B and BDX53C are silicon epitaxial-base NPN power transistors in monolithic Darlington configuration and are mounted in Jedec TO-220 plastic package. They are intented for use in hammer drivers, audio amplifiers and other medium power linear and INTERNAL SCHEMATIC DIAGRAM switching applications. The complementary PNP types for BDX53B and BDX53C are the BDX54B and BDX54C respectively. R Typ. = 10 K? R Typ. = 150 ? 1 2 ABSOLUTE MAXIMUM RATINGS Symbol Parameter Value Unit NPN BDX53A BDX53B BDX53C PNP