Automotive-grade NPN in a SOT-23 footprint
Packaged in the industry-standard SOT-23-3 (PG-SOT23) surface-mount case, it delivers a 45 V collector-emitter breakdown and a 500 mA continuous collector current ceiling.
The 250 minimum hFE at 100 mA, 1 Vce means the base drive requirement is low: for a 100 mA load, you need less than 0.4 mA into the base to keep the transistor in the linear region. When switching near the 500 mA maximum, the Vce saturation spec of 700 mV max at 50 mA base drive / 500 mA collector current tells you the on-state power dissipation: at 500 mA, figure about 350 mW worst-case, leaving 150 mW headroom before hitting the 500 mW package power limit. That margin shrinks at elevated ambient — derate against the 150°C junction maximum.
AEC-Q101 — what the automotive grade buys you
For a procurement decision, that certification lifts the part above the commercial BC817-40 variant — it is the version to specify when the BOM requires a PPAP submission or when the end product ships into under-hood or chassis-domain electronics. The 150°C junction temperature rating supports 125°C ambient operation with adequate derating for self-heating.
This is a standard catalog transistor that moves through both authorized distribution and the independent spot market. For production runs, qualify it into the BOM with confidence; the AEC-Q101 suffix is the automotive-screened variant, so confirm your tier's paperwork requirements at quote time.