2SC3991 Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 500 V
• Collector-Base Voltage, max: 800 V
• Emitter-Base Voltage, max: 7 V
• Collector Current − Continuous, max: 50 A
• Collector Dissipation: 300 W
• DC Current Gain (h_fe): 15 to 50
• Transition Frequency, min: 18 MHz
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: TO-3P

Here is an image showing the pin diagram of this transistor.The 2SC3991 transistor can have a current gain of 15 to 50. The gain of the 2SC3991-L will be in the range from 15 to 30, for the 2SC3991-M it will be in the range from 20 to 40, for the 2SC3991-N it will be in the range from 30 to 50.Sometimes the "2S" prefix is not marked on the package - the 2SC3991 might only be marked "C3991".