This part is a kind of semiconductor called BAS4.

Function of this product has Low-leakage diode.

Manufacturers : NXP

Image and pinout :

Some of the text within the PDF file :

DISCRETE SEMICONDUCTORS DATA SHEET book, halfpage M3D121 BAS45AL Low-leakage diode Product specification Supersedes data of 1999 May 04 1999 May 28 Philips Semiconductors Product specification Low-leakage diode FEATURES • Continuous reverse voltage: max. 125 V • Repetitive peak forward current: max. 625 mA • Low reverse current: max. 1 nA • Switching time: typ. 1.5 µs. APPLICATION • Low leakage current applications. handbook, 4 columns BAS45AL DESCRIPTION Epitaxial medium-speed switching diode with a low leakage current in a small SOD80C glass SMD package. k a MAM061 Fig.1 Simplified outline (SOD80C) and symbol. LIMITING VALUES In accordance with the Absolute Maximum Rating System (IEC 134). SYMBOL VRRM VR IF IFRM IFSM PARAMETER repetitive peak reverse voltage cont [ ... ]

BAS4 PDF Datasheet Download