800 V / 16 A standard TRIAC for mains switching
The STMicroelectronics T1635H-8T is a standard TRIAC in the ECOPACK®2 series, rated for 800 V off-state voltage and 16 A RMS on-state current. Packaged in a TO-220-3 through-hole case, it is designed for AC load switching in industrial and commercial equipment such as motor drives, lighting ballasts, heating controls, and solid-state relays. The 35 mA maximum gate trigger current (Igt) and 1.3 V maximum gate trigger voltage (Vgt) define the drive requirements for the control circuit, typically an optocoupler or a low-power transistor driver.
Gate drive and surge handling
With a maximum gate trigger current of 35 mA, the T1635H-8T requires a gate drive capable of sourcing that current at the 1.3 V threshold. This is a standard drive level for a 16 A triac, compatible with most optocoupler output stages or a small-signal transistor. The hold current (Ih) is also 35 mA maximum, meaning the load must draw at least that much to keep the triac latched after the gate pulse ends — a consideration for low-current loads like small fans or indicator lamps where a minimum load resistor may be needed. For inrush or fault conditions, the non-repetitive surge current rating is 160 A at 50 Hz and 168 A at 60 Hz. This covers the typical cold-start inrush of a motor or the charging current of a capacitive load, but the single-pulse nature of the rating means repeated surges will accumulate damage — the designer should size the triac so that the worst-case inrush stays within the surge capability with margin.
The TO-220-3 through-hole package allows for heatsink attachment via the metal tab, which is electrically isolated from the die but should be considered in the thermal design — the 16 A RMS rating assumes adequate heatsinking, not free-air operation. The package is ROHS3 compliant and lead-free per the ECOPACK®2 designation.