View bu508aw datasheet:

Philips Semiconductors Product specification Silicon Diffused Power Transistor BU508AW GENERAL DESCRIPTION High voltage, high-speed switching npn transistors in a plastic envelope, primarily for use in horizontal deflection circuits of colour television receivers. QUICK REFERENCE DATA SYMBOL PARAMETER CONDITIONS TYP. MAX. UNIT VCESM Collector-emitter voltage peak value VBE = 0 V - 1500 V VCEO Collector-emitter voltage (open base) - 700 V IC Collector current (DC) - 8 A ICM Collector current peak value - 15 A Ptot Total power dissipation Tmb ? 25 ?C - 125 W VCEsat Collector-emitter saturation voltage IC = 4.5 A; IB = 1.6 A - 1.0 V ICsat Collector saturation current f = 16 kHz 4.5 - A tf Fall time ICsat = 4.5 A; f = 16kHz 0.7 - µs PINNING - SOT429 PIN CONFIGURATION SYMBOL P