Triac coupler with zero-crossing for clean switching
The Toshiba TLP268J(T2-TPL,E is a single-channel triac output optocoupler in a 6-SOP surface-mount package. It provides 3750Vrms isolation between the LED input and the triac output, with a 600 V off-state voltage rating. The built-in zero-crossing circuit triggers the output only near the AC zero-voltage point, which reduces inrush current when driving resistive or lightly inductive loads like solid-state relays, heater controls, and lamp ballasts.
The static dV/dt rating of 500 V/µs (typical) is the key parameter for avoiding false turn-on in electrically noisy environments — motor drives, inverter stages, and switching power supplies generate fast voltage transients across the off-state triac. A coupler with insufficient dV/dt immunity can self-trigger, causing partial conduction and load glitching. The 70 mA RMS on-state current limits the coupler to driving low-power loads directly (small fans, indicator lamps, solenoid pilots); for higher currents it drives an external power triac or SSR. The 200 µA typical holding current ensures the triac latches cleanly once triggered and does not drop out prematurely on a low-current load.
Package and temperature range for production assembly
The 1.27 V typical forward voltage and 30 mA max LED current are standard for the LED side; the 100 µs turn-on time is fast enough for 50/60 Hz line-frequency switching but not for high-speed PWM dimming.