What the 1.5SMCJ43CA-AQ does
The 1.5SMCJ43CA-AQ is a bidirectional Zener-based TVS (transient voltage suppressor) in the DO-214AB (SMC) surface-mount package. Bidirectional means it clamps both polarities of a voltage surge — a spike above the standoff threshold in either direction gets steered away from the protected node and clamped at the datasheet ceiling.
Voltage ratings and what they govern
The reverse standoff voltage of 43 V is the working DC rail the diode watches — it sits off-state across this voltage in normal operation and draws only leakage current. At 21.6 A through the device under surge, the clamping voltage of 69.4 V is the let-through the IC or MOSFET gate sees — sizing the downstream protection to tolerate that ceiling is the first design check. The 1.5 kW peak pulse rating (vs the common 1.2 kW SMC rating) gives additional headroom for the same package footprint, which matters when the surge threat profile is higher than nominal.
Automotive temperature grade and environment
The junction rating is the governing limit; the board-level temperature around the SMC solder pad determines whether the Tj ceiling is approached. Listed under automotive applications and shipped in strip packaging for pick-and-place assembly, the part fits the DO-214AB footprint standard — the same land pattern as any SMC-device migration path if a second source becomes necessary.
Diotec Semiconductor lists the 1.5SMCJ43CA-AQ as Active — orderable under the listed part number with availability and lead time confirmed at quote.