Schottky pair in a small SOT-323
The STMicroelectronics BAT54CWFILM is a dual Schottky barrier diode in a common-cathode configuration, housed in an SOT-323 package. It is rated for 40 V reverse voltage and 300 mA average rectified current per diode, with a 5 ns reverse recovery time that suits high-frequency clamping and switching applications.
5 ns recovery — what it buys you
The 5 ns reverse recovery time (trr) is the headline switching parameter. In a flyback snubber or a high-side bootstrap clamp, that fast recovery means the diode stops conducting almost immediately after the voltage reverses, minimising the stored charge that would otherwise cause ringing or overshoot. For a 300 mA average current rating, the trr is comfortably inside the 500 ns threshold that qualifies as fast recovery.
Common-cathode layout reality
The SOT-323 footprint is 2.0 mm × 1.25 mm, so the layout engineer gets two diodes in the board area of a single small-signal SOT-23.