70 V rail clamp for automotive 48 V and 24 V buses
With a 70 V reverse standoff voltage and a minimum breakdown voltage of 77.8 V, it sits above the nominal 48 V and 24 V automotive bus voltages, providing a guard band against steady-state overvoltage without conducting during normal operation. The 146 V clamping voltage at 27 A peak pulse current defines the maximum surge voltage the downstream circuitry must survive. Typical applications include clamping on 48 V mild-hybrid buses, 24 V truck/off-road vehicle power lines, and industrial 48 V DC supplies where automotive-grade robustness is specified.
Clamping voltage and surge current — what the ratings mean
The 146 V clamping voltage at 27 A (8/20 µs waveform) is the maximum voltage the TVS will let through during a surge event. For a 48 V bus protected by this part, that means the downstream DC/DC converter or load must be rated for at least 146 V transient withstand. For longer transients (10/1000 µs waveform, also listed at 27 A), the same current rating suggests the device has a flat power-handling characteristic across that pulse range, which is typical for a robust TVS design.
For the BOM, this removes the obsolescence risk that can force a last-minute redesign. The base product number is SM6T82, so the 'Y' suffix indicates the automotive-grade AEC-Q101 screening — the non-automotive variant (SM6T82A) is the same die without the automotive qualification step.
Package and footprint: DO-214AA (SMB)
The SM6T82AY is supplied in the DO-214AA (SMB) package, a standard surface-mount outline for TVS diodes with a 4.6 mm body length and 3.6 mm width. The SMB footprint is shared with many other TVS parts in the SM6T family, so a board layout designed for the SM6T82A (non-automotive) accepts the SM6T82AY without modification. The single unidirectional channel means it protects one rail; for bidirectional protection on AC or bipolar rails, two devices back-to-back are needed. No power line protection feature is built in — this is a standard TVS, not a dedicated ESD or surge-protection IC with integrated filtering.