1. SMA6J28A Substitution Conclusion The SMA6J28A can fully replace the original SMAJ28A, offering superior key protection performance. Both devices share identical core parameters—a reverse standoff voltage of 28 V and a minimum breakdown voltage of 31.1 V—and the same DO-214AC package, ensuring fundamental compatibility. The main differences are as follows: the clamping voltage of the SMA6J28A (44 V) is approximately 3 % lower than that of the original model (45.4 V), which limits the maximum voltage across the protected circuit to a lower level during a surge, thereby providing enhanced protection. Additionally, its peak pulse current (13.6 A) and power rating (600 W) are significantly higher than those of the original model (8.8 A, 400 W), indicating a greater capacity to absorb transient overvoltage energy, making it suitable for more demanding surge environments. In summary, while maintaining electrical compatibility and package consistency, the SMA6J28A delivers improved overvoltage clamping capability and surge endurance. It can be used as a direct replacement to enhance system reliability.