Package and mounting
The BAR43CFILM is a dual Schottky diode array from STMicroelectronics, with two diodes in a common-cathode configuration inside a single SOT-23-3 package. Each diode is rated for 30 V reverse voltage and 100 mA average rectified current — the numbers a repair tech checks first when a low-voltage rail or signal clamp has failed. The 5 ns reverse recovery time tells you this is a fast-switching Schottky, not a 50 Hz rectifier. It is meant for high-frequency steering, OR-ing, and clamping in circuits where a standard silicon diode would leave a voltage droop or a slow tail.
Leakage and forward drop — the numbers that decide standby draw
Reverse leakage is spec'd at 500 nA maximum at 30 V — low enough that it will not drain a battery in a power-path OR-ing application, but worth checking against the actual operating voltage because leakage rises with junction temperature. Forward voltage is 1 V maximum at 100 mA, which is typical for a small-signal Schottky at this current.
SOT-23-3 footprint and common-cathode pinout
The SOT-23-3 package (also listed as TO-236-3 / SC-59) is a standard three-lead surface-mount footprint.