The Infineon BAS 40-04 B5003 is a dual series-connected Schottky diode in a SOT-23-3 surface-mount package. It handles up to 40 V reverse voltage and 120 mA average rectified current per diode, with a reverse recovery time of 100 ps — typical for a small-signal Schottky. The series configuration is useful for applications like high-speed switching, OR-ing diodes, and clamping in low-voltage, low-current rails. The 150 °C maximum junction temperature suits it for warm environments inside a power supply or industrial controller, though the SOT-23 package limits total dissipation.
Obsolete — what that means for a BOM line
Infineon lists the BAS 40-04 B5003 as obsolete. Any new design should avoid this part; for existing boards, the procurement team should qualify a pin-compatible replacement or secure a last-time-buy lot through a broker.
The 40 V reverse voltage rating covers typical 12 V and 24 V rails with margin, but not 48 V systems. The 120 mA average current per diode is a small-signal level — fine for logic-level OR-ing, signal clamping, or detector circuits, but not for power rectification. The 100 ps reverse recovery time is the headline spec for a Schottky: it enables clean switching in RF detectors, high-speed data-line protection, or switching regulators running above 1 MHz. Forward voltage drops 1 V at 40 mA, which is higher than some low-Vf Schottkys, so for battery-powered circuits with sub-100 mA loads the forward loss may matter. Reverse leakage is 1 µA at 30 V — typical for a 40 V Schottky, but worth checking if the circuit operates near the maximum reverse voltage at elevated temperature, where leakage climbs.