25 A RMS, 600 V — the Snubberless™ alternistor for inductive loads
The BTA24-600BW is a 25 A RMS Snubberless™ alternistor triac from STMicroelectronics, rated for 600 V off-state blocking. The Snubberless™ construction means the device is designed to commutate inductive loads — motors, solenoids, transformer primaries — without the external RC snubber network that standard triacs need to prevent false turn-on from dV/dt transients.
STMicroelectronics has marked the BTA24-600BW as Obsolete. For a BOM line that already uses this triac, the TO-220 footprint and 25 A / 600 V rating are the parameters to match when selecting a replacement — the Snubberless™ alternistor topology is not unique to this part number, and several manufacturers offer functionally equivalent devices in the same package.
TO-220 package — board-fit and thermal management
The BTA24-600BW comes in a standard TO-220-3 through-hole package. The metal tab is the MT2 terminal and is electrically live — it must be isolated from the heatsink unless the heatsink is at the same potential. For a 25 A RMS load, the tab-to-ambient thermal resistance dictates the heatsink size; the junction temperature must stay within the -40°C to 125°C range. The 260 A surge rating means the die can handle short-term overloads, but the steady-state thermal design governs the continuous current the part can actually carry in a given enclosure.