The FMMT624TA is an NPN bipolar junction transistor in a SOT-23-3 package, rated for 125V collector-emitter breakdown and 1A continuous collector current.
What the gain and saturation specs mean for the BOM
DC current gain (hFE) is guaranteed minimum 300 at Ic=200mA, Vce=10V — this high gain means the base drive current can be kept low in a 200mA load leg, reducing the upstream driver stage dissipation. Vce(sat) is 250mV maximum at Ic=1A, Ib=50mA — the low saturation voltage keeps conduction losses under 250mW at full collector current, which is within the 625mW package limit even without a large copper pour. Transition frequency is 155MHz, sufficient for switching applications up to several megahertz — the SOT-23-3 package inductance and board layout will dominate the practical switching speed ceiling before the transistor's fT does.
Package, footprint, and board integration
Supplied in SOT-23-3 (TO-236-3, SC-59) surface-mount package, the collector is the center pin — the standard SOT-23 footprint with a small copper pad under the collector tab is adequate for 625mW dissipation in still air.