1500 W peak pulse — what that means for layout
The 1.5SMBJ43A-H: In a real transient, the power dissipated is the product of the clamping voltage and the surge current — at 21.7 A and 69.4 V that is roughly 1.5 kW for 1 ms. This is a unidirectional Zener TVS — one channel per package, with the cathode identified by the band. It is intended for signal and DC power lines, not AC mains; the 'Power Line Protection: No' spec confirms it should not be used on the line side of a rectifier or transformer.