The BC 817-40 E6327: General-purpose NPN bipolar junction transistor in a SOT-23-3 surface-mount package. Rated for a collector current of 500 mA and a collector-emitter breakdown voltage of 45 V, with a minimum DC current gain of 250 at 100 mA collector current and 1 V VCE.
Listed as obsolete by Infineon. Sourcing is limited to independent distribution and surplus inventory. For new designs or volume production, a pin-compatible alternative within the BC 817 family should be evaluated.
The 500 mA collector current rating sets the maximum continuous load the transistor can handle; designs should derate for ambient temperature and power dissipation. The 45 V VCEO breakdown is the maximum voltage between collector and emitter with the base open — stay below this to avoid avalanche breakdown. The minimum hFE of 250 at 100 mA ensures consistent gain across devices, which simplifies bias network design. The 170 MHz transition frequency indicates the transistor can switch at tens of MHz with appropriate drive. Maximum power dissipation is 330 mW, which in the SOT-23-3 package limits continuous current at higher voltages.