50 V, 500 mA NPN in a SOT-23-3 — what it covers
The ROHM 2SD1484KT146Q is a general-purpose NPN bipolar transistor in a SOT-23-3 surface-mount package. The DC current gain (hFE) is guaranteed at a minimum of 120 when measured at 10 mA collector current and 3 V Vce. Maximum power dissipation is 200 mW. This part is suited for switching and linear amplification in circuits where the collector supply stays at or below 50 V and load current does not exceed 500 mA — common in relay drivers, solenoid pre-drivers, and low-power DC-DC converter feedback loops.
ROHS3 compliant.
Supplied in a TO-236-3 / SC-59 / SOT-23-3 case, surface-mount only. The SOT-23-3 footprint is standard and shared across many small-signal transistors, so board layout is straightforward. No exposed pad — all dissipation goes through the three leads and the plastic body.
The 50 V Vce breakdown sets the absolute maximum collector supply; for a 24 V or 48 V bus, derate by at least 20% for switching transients. The 500 mA continuous collector current defines the load-driving limit — a relay coil rated at 200 mA leaves margin; a 450 mA load is tight. The 250 MHz transition frequency means the transistor can switch at several tens of MHz, but the SOT-23-3 package limits practical switching speed due to thermal constraints above a few hundred milliamps. The 200 mW power budget means the product of Vce and Ic must stay under 200 mW — at 50 V the maximum continuous current is only 4 mA; at 5 V it is 40 mA. For switching applications, the average power is lower, but the thermal limit still governs.