MMBT5550 Bipolar Transistor

• Type: NPN
• Collector-Emitter Voltage, max: 140 V
• Collector-Base Voltage, max: 160 V
• Emitter-Base Voltage, max: 6 V
• Collector Current − Continuous, max: 0.6 A
• Collector Dissipation: 0.35 W
• DC Current Gain (h_fe): 60 to 250
• Transition Frequency, min: 100 MHz
• Operating and Storage Junction Temperature Range: -55 to +150 °C
• Package: SOT-23

Here is an image showing the pin diagram of this transistor.The MMBT5550 transistor is marked as "1F".You can replace the MMBT5550 with the FMMT625 or KST5550.