800 V Alternistor for inductive loads — no snubber needed
The STMicroelectronics T635T-8T is a 6 A RMS Alternistor TRIAC from the Snubberless™ series, rated for 800 V off-state voltage and housed in a TO-220 through-hole package. It is designed for AC load switching in industrial and appliance environments where inductive kickback would otherwise demand an external RC snubber — the Snubberless™ construction handles the dv/dt transient internally. Typical applications include motor speed controllers, heating-element drivers, solid-state relays, and lighting ballasts where the 150°C junction temperature rating provides margin for thermally constrained enclosures.
Gate drive and triggering
The T635T-8T triggers with a maximum gate current of 35 mA and a maximum gate voltage of 1.3 V. A holding current of 40 mA ensures the device latches once triggered, so the gate drive can be removed after the half-cycle. For designs using a microcontroller or optocoupler output, confirm the driver can source 35 mA peak into the gate — many logic-level couplers need a buffer transistor at this level.
Through-hole TO-220-3 package with a standard TO-220AB footprint. The tab is electrically common with the center pin (MT2), so heatsink mounting requires an insulating washer and thermal compound if the heatsink is grounded.
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