45 V, 500 mA NPN in SOT-323 — general-purpose switching transistor
The Infineon BC817K25WH6433XTMA1 is a 45 V, 500 mA NPN epitaxial silicon transistor in a SC-70/SOT-323 surface-mount package. It is designed for general-purpose switching and amplification in low-power circuits, with a transition frequency of 170 MHz and a DC current gain (hFE) of 160 minimum at 100 mA collector current.
That means the manufacturer has announced end-of-life and the final production window is closing. For any active BOM line using this transistor, the procurement decision is immediate: place a last-time-buy quantity to cover remaining production, or qualify a replacement.
The 45 V collector-emitter breakdown voltage gives headroom on 24 V industrial rails and 12 V automotive supplies, but does not leave margin for 48 V systems. The 500 mA continuous collector current handles relay coils, LED drivers, and small solenoid loads — derate for ambient temperature above 25 °C. The 250 mW power dissipation in the SOT-323 package limits continuous current at higher voltages; check the thermal derating curve for your operating point.