600W unidirectional transient suppressor for 33.3V rails
The STMicroelectronics SM6T39A is a 600W unidirectional TRANSIL™ TVS diode in a DO-214AA (SMB) surface-mount package, designed to clamp transients on DC power rails and signal lines with a 33.3V reverse standoff voltage.
Voltage thresholds and clamping margin
Three voltage numbers define where this part fits on a rail. The 33.3V reverse standoff is the maximum DC voltage the diode will not conduct at — a 24V nominal bus with 30% tolerance sits safely below it. Breakdown starts at 37.1V minimum, and clamping hits 69.7V maximum at the rated 57A peak pulse current. That 69.7V clamp is the voltage the protected circuitry must survive for the pulse duration; a 60V-rated downstream regulator would need a second stage or a higher-voltage part upstream.
Active lifecycle and BOM planning
The TRANSIL series has broad distribution coverage, which supports multi-source procurement without sole-source exposure.