BC257C Bipolar Transistor

• Type: PNP
• Collector-Emitter Voltage, max: -45 V
• Collector-Base Voltage, max: -50 V
• Emitter-Base Voltage, max: -6 V
• Collector Current − Continuous, max: -0.1 A
• Collector Dissipation: 0.3 W
• DC Current Gain (h_fe): 420 to 800
• Transition Frequency, min: 180 MHz
• Noise Figure, max: 2 dB
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: TO-92

The BC257C 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 BC257C transistor can have a current gain of 420 to 800. The gain of the BC257 will be in the range from 110 to 800, for the BC257A it will be in the range from 110 to 220, for the BC257B it will be in the range from 200 to 450.The complementary NPN transistor to the BC257C is the BC167C.The BC857 (SOT-23), BC857C (SOT-23), BC857CW (SOT-323), BC857W (SOT-323), BC860 (SOT-23), BC860C (SOT-23), BC860CW (SOT-323), BC860W (SOT-323), KST5087 (SOT-23) and MMBT5087 (SOT-23) is the SMD version of the BC257C transistor. These transistors are of the same type, have similar parameters and are designed for surface mounting.You can replace the BC257C with the 2SA1025, 2SA1025-E, 2SA1081, 2SA1081-E, 2SA1083, 2SA1083-E, 2SA1084, 2SA1084-E, 2SA1287, 2SA1287-G, 2SA1522, 2SA1523, 2SA1524, 2SA1525, 2SA1526, 2SA1527, 2SA1528, 2SA1529, 2SA990, 2SA990E, 2SA991 or 2SA991E.