2SA1091 Bipolar Transistor

• Type: PNP
• Collector-Emitter Voltage, max: -300 V
• Collector-Base Voltage, max: -300 V
• Emitter-Base Voltage, max: -8 V
• Collector Current − Continuous, max: -0.1 A
• Collector Dissipation: 0.4 W
• DC Current Gain (h_fe): 30 to 150
• Transition Frequency, min: 60 MHz
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: TO-92

The 2SA1091 is manufactured in a plastic TO-92 case. When looking at the flat side with the leads pointed downward, the three leads emerging from the transistor are, from left to right, the emitter, collector, and base leads.
Here is an image showing the pin diagram of this transistor.The 2SA1091 transistor can have a current gain of 30 to 150. The gain of the 2SA1091-O will be in the range from 50 to 150, for the 2SA1091-R it will be in the range from 30 to 90.Sometimes the "2S" prefix is not marked on the package - the 2SA1091 might only be marked "A1091".The complementary NPN transistor to the 2SA1091 is the 2SC2551.The 2SA1721 (SOT-23) is the SMD version of the 2SA1091 transistor. These transistors are of the same type, have similar parameters and are designed for surface mounting.