The Z0103DN 5AA4 is a logic-level triac from STMicroelectronics rated for 400 V off-state voltage and 1 A RMS on-state current. The 400 V off-state rating covers 230 VAC mains switching with adequate headroom for line transients, while the 1 A RMS continuous current suits small inductive loads like relays, solenoids, or low-power fan motors. The sensitive-gate design (3 mA max trigger current) lets this triac be driven directly from a microcontroller GPIO or logic-level output without an intermediate transistor stage — a common requirement in appliance control boards and solid-state relay modules. With a holding current of 7 mA max, the device latches reliably once triggered, preventing premature dropout on low-current loads. The 8.5 A non-repetitive surge rating (60 Hz) handles inrush from lamp filaments or capacitive loads during turn-on.
SOT-223 package — board integration for compact designs
The Z0103DN 5AA4 comes in the SOT-223 surface-mount package (TO-261-4, TO-261AA). This three-lead package with an exposed tab on the drain/MT2 terminal suits reflow assembly and keeps the board footprint small — about 6.5 mm × 3.5 mm — fitting into compact power-supply or control PCBs. At the upper end, the 1 A RMS rating should be derated per the device's thermal impedance; the SOT-223 tab can be soldered to a copper plane for improved heat spreading.
STMicroelectronics has marked the Z0103DN 5AA4 as obsolete. The part is no longer available through standard authorized distribution channels. Availability is lot-specific and confirmed at RFQ time.