120V dual PNP in a SC-74A — what it brings to the board
The Toshiba HN4A51JTE85LF is a dual PNP small-signal transistor in a surface-mount SC-74A (SOT-753) package. Each transistor is rated for a collector-emitter breakdown of 120V, a continuous collector current of 100mA, and a transition frequency of 100MHz. The 300mW power dissipation limit applies to the whole package, not per transistor. With a DC current gain (hFE) of 200 minimum at 2mA collector current and 6V Vce, it offers consistent gain for analog stages. The 150°C junction temperature rating gives thermal headroom in warm environments like industrial control cabinets or automotive auxiliary circuits.
Saturation voltage and cutoff — the switching margins
Vce saturation is specified at 300mV maximum with a 1mA base current driving 10mA collector current — a low enough drop for logic-level relay and solenoid drivers. Collector cutoff current is 100nA maximum, which keeps leakage negligible in high-impedance bias networks or off-state loads.