What the 20V standoff and 32.4V clamping mean for the board
The 1.5SMCJ20A-AQ is a unidirectional Zener-type TVS designed for automotive board-level protection — it sits across a rail and clamps transients once the standoff voltage is exceeded.
Junction thermal rating and automotive temperature exposure
Maximum junction temperature is 150 °C (TJ) — this sits at the upper end of the automotive Grade 1 range (-40 to 125 °C ambient), leaving the typical 25 °C delta as headroom for transient thermal rise during a clamping event. At the 46.3 A peak pulse the instantaneous dissipation is roughly 1.5 kW; the datasheet thermal impedance is what governs whether the TJ limit is breached on a repetitive surge sequence, so check the I²t and thermal derating curves if the board sees burst transients.
SMC package, strip packaging, and automotive assembly context
The SMC (DO-214AB) is the mid-size automotive TVS footprint — larger than the SMA (DO-214AC) and smaller than the SMB (DO-214AA), which determines the available land pattern and pad area on a typical ECU board. Supplied in strip format for pick-and-place; the exposed pad on the cathode side requires adequate solder wetting to manage thermal dissipation from the junction through the lead frame to the board copper.