600 V, 4 A RMS standard TRIAC in I-PAK
The STMicroelectronics Z0409MH is a standard TRIAC rated for 600 V off-state voltage and 4 A RMS on-state current, with a non-repetitive surge capability of 15 A at 50 Hz and 16 A at 60 Hz — enough to handle inrush from a small motor or lamp load without external snubber in many designs. Housed in a TO-251-3 I-PAK through-hole package, it mounts directly into a PCB with short leads, suiting compact board layouts where a TO-220 would overhang the edge.
Gate drive and temperature envelope
Maximum gate trigger current (Igt) is 10 mA and gate trigger voltage (Vgt) is 1.3 V, so a standard 5 V logic output through a current-limiting resistor can fire it — no special driver needed for low-power control circuits. Hold current (Ih) is 10 mA max, meaning the TRIAC latches on once triggered and stays conducting until the load current drops below that threshold — important for inductive loads where the current zero-cross may not align with the gate pulse. Operating junction temperature range is -40°C to 125°C, covering industrial and outdoor equipment enclosures without derating at the high end.
Lifecycle and compliance
Part of the ECOPACK2 series, which means the package materials and plating meet ST's lead-free and halogen-free criteria per their internal green-packaging standard.