2SA503-O Bipolar Transistor

• Type: PNP
• Collector-Emitter Voltage, max: -50 V
• Collector-Base Voltage, max: -60 V
• Emitter-Base Voltage, max: -5 V
• Collector Current − Continuous, max: -0.6 A
• Collector Dissipation: 6 W
• DC Current Gain (h_fe): 50 to 150
• Transition Frequency, min: 130 MHz
• Operating and Storage Junction Temperature Range: -65 to +175 °C
• Package: TO-39

Here is an image showing the pin diagram of this transistor.The 2SA503-O transistor can have a current gain of 50 to 150. The gain of the 2SA503 will be in the range from 30 to 300, for the 2SA503-GR it will be in the range from 100 to 300, for the 2SA503-R it will be in the range from 30 to 90.Sometimes the "2S" prefix is not marked on the package - the 2SA503-O might only be marked "A503-O".The complementary NPN transistor to the 2SA503-O is the 2SC503-O.The FMMTA55 (SOT-23) and KST55 (SOT-23) is the SMD version of the 2SA503-O transistor. These transistors are of the same type, have similar parameters and are designed for surface mounting.You can replace the 2SA503-O with the 2N2102, 2N2102A, 2N4235, 2N4236, 2N5322, 2N5323, 2N5679, 2SA510, 2SA510-O, 2SA512, 2SA512-O, BC161 or BC461.