The Infineon BC 817-25W E6433 is an NPN general-purpose transistor in a SOT-323 (SC-70) surface-mount package. It is rated for 45 V collector-emitter breakdown and 500 mA continuous collector current, with a minimum DC current gain of 160 at 100 mA and a transition frequency of 170 MHz.
Parametric profile and application fit
With a 45 V VCEO and 500 mA Ic rating, this transistor suits low-to-medium power switching and amplification roles: relay drivers, LED drivers, signal amplification in audio or control circuits, and general-purpose switching up to a few MHz. The 170 MHz fT supports moderate-speed switching, though for higher-frequency RF applications a dedicated RF transistor would be needed. The SOT-323 footprint is compact, saving board space compared to SOT-23, but the 250 mW power limit means thermal dissipation must be checked in continuous-load designs — derating is required above 25 °C ambient.
hFE bin and family context
The -25W suffix denotes a specific hFE bin: minimum 160 at 100 mA, 1 V, with a typical range of 160 to 400. This is the medium-gain bin in the BC 817 family; the -16W bin offers lower gain (100 min) and the -40W bin higher gain (250 min). For designs requiring a tighter gain window at the operating point, the -25W bin is a common choice. The base part number BC 817 covers multiple package variants (SOT-23, SOT-323, SOT-89) and hFE bins, so a direct replacement must match both the package and the gain grade.