The BCX54 from JSMicro Semiconductor is a Bipolar Junction Transistor with Emitter Base Voltage 5 V, Collector Base Voltage 45 V, Collector Cut off Current 20 µA, Collector Emitter Breakdown Voltage 45 V, Collector Emitter Voltage 45 V. Tags: Surface Mount, NPN Transistor. More details for BCX54 can be seen below.