Automotive-grade TVS in a DO-214AA footprint
The 1.5SMBJ70A-H: AEC-Q101 qualification confirms this part is screened for automotive-grade reliability — operating junction temperature from -55 °C to 150 °C covers under-hood and engine-bay ambient conditions where the thermal cycling and surge exposure exceed commercial-grade limits.
Voltage clamping and pulse current profile
This means a 70 V nominal rail experiencing a load-dump or inductive kickback is clamped well below the typical 150 V abs-max of downstream DC-DC converters and ECUs — the margin is about 37 V below a 150 V device limit. The unidirectional configuration conducts the surge to ground in the forward direction and clamps the reverse polarity through Zener breakdown. For circuits that already have a reverse-polarity protection diode upstream, the unidirectional part is the standard choice; a bidirectional variant would be needed only if the signal swings below ground.
Package, mounting and sourcing posture
The SMB footprint is a standard JEDEC outline — the same pad layout used by the SMC (DO-214AB) family for higher power ratings, but with a smaller body that saves board area when 1500 W is sufficient.