The STMicroelectronics T835H-6G-TR is an 8 A RMS Snubberless Alternistor triac in a surface-mount D2PAK package, rated for 600 V off-state blocking. It belongs to the Snubberless series.
8 A RMS — sizing the load and the heatsink
The 8 A RMS on-state current is the continuous rating. The gate trigger voltage is 1 V maximum.
Snubberless Alternistor — what it saves you
A standard triac switching an inductive load needs a series RC snubber to limit dV/dt. The Snubberless Alternistor construction inherently withstands higher dV/dt, so you can omit the snubber.
Gate drive: 35 mA Igt, 1 V Vgt
The gate trigger current is 35 mA maximum, and the gate trigger voltage is 1 V maximum.
Package and mounting: D2PAK (TO-263AB)
The tab is electrically connected to the MT2 terminal.
There is no official replacement because the part is current; if you need a higher current rating in the same Snubberless family, the T3035H-6G-TR (30 A) shares the same 600 V blocking and 150°C Tj max, but in a through-hole or surface-mount package depending on suffix.