400W bidirectional TVS for 40V automotive rails
It provides 400W peak pulse power dissipation (10/1000µs waveform) with a 40V reverse standoff voltage and an 84V maximum clamping voltage at the rated peak pulse current. The single bidirectional channel makes it a straightforward choice for protecting 40V nominal power buses, sensor lines, or signal pairs in automotive ECUs, body controllers, and ADAS modules.
The 44.4V minimum breakdown voltage is the threshold where the device starts conducting; below that, it appears as a high-impedance open circuit. The 84V maximum clamping voltage at the 27A peak pulse current (8/20µs waveform) is the voltage the protected circuitry must survive — a 40V-rated bus with 20% margin sees 84V as a hard transient ceiling. The 400W peak pulse power rating governs how much energy the part can absorb in a single surge event; for repetitive transients, derate per the datasheet's pulse derating curve, which is on page 7 of the SM4TY series application note.
AEC-Q101 qualification and temperature range
SMA package and board integration
The SM4T47CAY is housed in a DO-214AC (SMA) package, a standard surface-mount footprint for automotive TVS diodes. The SMA body is small enough for dense PCB layouts but still provides adequate thermal mass for the 400W pulse rating when the PCB copper is used as a heatsink.