NPN transistor, 45 V, 500 mA — SOT-23 general-purpose switch
The Infineon BC 817-25 B5003 is an NPN epitaxial silicon transistor in a surface-mount SOT-23 package (PG-SOT23), designed for general-purpose switching and amplification up to 45 V collector-emitter breakdown and 500 mA continuous collector current. With a DC current gain (hFE) of 160 minimum at 100 mA, 1 V, and a transition frequency of 170 MHz, it suits medium-speed switching in power management, relay drivers, and signal preamplifier stages. Maximum power dissipation is 330 mW, and the junction temperature rating reaches 150 °C.
Obsolete — plan for last-time-buy or cross-reference
The BC 817-25 B5003 carries an Obsolete product status. For new designs or production continuity, a pin-compatible replacement within the BC 817 family should be evaluated — the base part number BC 817 covers multiple hFE grades and package variants that may still be active. For existing BOM lines, sourcing through independent distribution or surplus stock is the practical path; we can quote against an RFQ from our multi-source network.
Key ratings for BOM fit
The 45 V VCEO breakdown sets the maximum rail voltage this transistor can block in off-state — suitable for 24 V and 36 V industrial buses with margin. The 500 mA collector current rating covers solenoid, relay, and small motor drive stages; for continuous loads above 300 mA, derate for the 330 mW power limit in the SOT-23 package. Saturation voltage is 700 mV maximum at 50 mA base drive and 500 mA collector current, which matters for low-drop switching efficiency. The 100 nA collector cutoff current ensures negligible leakage in high-impedance or battery-powered circuits.