The Infineon BAS40-04B5003 is a dual Schottky diode in a series-connected configuration, housed in a standard SOT-23-3 surface-mount package. This part is qualified to AEC-Q101, making it suitable for automotive under-hood and cabin electronics, as well as industrial control, power supply OR-ing, and high-speed switching where fast recovery and low forward drop matter.
40 V reverse voltage and 120 mA — what that buys you
The series configuration (cathode of one diode to anode of the other) lets you build a voltage doubler or a bidirectional clamp in one package, saving board space over two discrete SOT-23s.
AEC-Q101 and junction temperature
AEC-Q101 qualification means this diode has passed automotive-grade stress tests including HBM ESD, temperature cycling, and high-temperature reverse bias. The active lifecycle status means Infineon is still manufacturing this part — no last-time-buy risk for production runs.
SOT-23-3 — field-swappable footprint
The SOT-23-3 package (also known as TO-236-3 or SC-59) is one of the most common three-pin surface-mount footprints. It is easy to hand-solder with a fine-tip iron, and the part marking is usually legible under a loupe. No hot-air station needed for rework — a field swap is straightforward if you have tweezers and a steady hand.