SMAJ58A-TR: 58V unidirectional TVS in the DO-214AC footprint
The STMicroelectronics SMAJ58A-TR is a unidirectional Zener transient voltage suppressor from the SMAJ / TRANSIL™ series, housed in a surface-mount DO-214AC (SMA) package. It is designed for general-purpose overvoltage protection, clamping transients at 93.6V maximum with a peak pulse current of 4.3A under the 10/1000µs waveform. The 400W peak pulse power rating and 58V reverse standoff voltage make it a direct fit for protecting 48V nominal rails or 58V DC buses against surges in industrial control, telecom, and automotive auxiliary circuits.
The minimum breakdown voltage of 64.4V ensures the device starts conducting before the protected circuitry sees damaging overvoltage, while the maximum clamping voltage of 93.6V at 4.3A defines the worst-case voltage the load must survive. For a 58V rail, this leaves about 6.4V of margin above the nominal operating voltage before leakage rises — typical for a TVS protecting a DC bus with ±10% tolerance. The 4.3A peak pulse current capability (10/1000µs) translates to roughly 400W of surge energy absorption, adequate for secondary protection in equipment rated to IEC 61000-4-5 Level 2 or similar.
For procurement, this translates to predictable lead times through authorized distribution and no forced last-time-buy planning.
The DO-214AC (SMA) package is a standard JEDEC outline for surface-mount TVS diodes, compatible with reflow soldering and automated pick-and-place. No power line protection feature is built in — this is a pure unidirectional transient clamp, not a steering diode array.