This part is a kind of semiconductor called BAT54.

Function of this product has SURFACT MOUNT SCHOTTKY BARRIER.

Manufacturers : Pan Jit International Inc.

Image and pinout :

Some of the text within the PDF file :

BAT54, BAT54A, BAT54C, BAT54S SURFACT MOUNT SCHOTTKY BARRIER VOLTAGE 30 Volts FEATURES • Low turn-on voltage • Fast switching • PN Junction Guard Ring for Transient and ESD Protection. CURRENT 0.2 Ampers PACKAGE SOT-23 MECHANICAL DATA Case: SOT-23, Plastic Terminals: Solderable per MIL-STD-202, Method 208 Approx. Weight: 0.008 gram Marking: L4, L42, L43, L44 MAXIMUM RATINGS AND ELECTRICAL CHARACTERISTICS Ratings at 25OC ambient temperature unless otherwise specified. Single phase, half wave, 60 Hz, resistive or inductive load. For capacitive load, derate current by 20%. Parameter Peak Repetitive Reverse Voltage Maximum Average Forward Current at Ta=25OC Peak Forward Surge Current, 8.3ms single half sine-wave superimposed on rated load (JEDEC method) Maximum Instantaneous Forwar [ ... ]

BAT54 PDF Datasheet Download