WEE Technology Company Limited
Manufacturer of Surface Mount (SMD) and Through Hole (DIP) Diodes & Rectifiers

NPN Silicon Epitaxial Planar Transistor for general purpose applications, SOT-23 Plastic Package

This type of transistor is subdivided into five groups , they are R, O,Y, P and L according to its DC current gain. As complementary type the PNP transistorMMBTSA733 is recommended. 

DC Current Gain at VCE = 6 V, IC = 1 mA 

MMBTSC945R:  40hFE Min and 80hFE Max.

MMBTSC945O: 70hFE Min and 140hFE Max.

MMBTSC945Y: 120hFE Min and 240hFE Max.

MMBTSC945P:200hFE Min and 400hFE Max.

MMBTSC945L 350hFE Min and 700hFE Max.

What's the difference between SOT-23 package and SOT-323 package in SMT (Surface Mounted Transistors)? How does them look the same? How to distinguish them?

the main difference between SOT-23 package and SOT-323 package is the size difference.  If put them together, the main body of SOT-323 is shorter and SOT-23 is longer. Compared with SOT-23, SOT-323 is much smaller; furthermore, the foot spacing of SOT-323 is also different, and SOT-323 is narrower than SOT-23.

To know more about this package, we would like to draw your attention that SOT is a surface mounted package with pins less than or equal to 5 small leads transistors. Such as SOT-23, SOT-323, SOT-523, SOT-223,SOT-23-3 and so on.

Small Outline Transistor (SOT) packages are very small dimensions, usually are plastic-molded packages with more than 3 leads on their two long sides. Due to their low cost and low profile, SOT's are commonly used in consumer electronics. The SOT-23 and the SC-70 packages are two of the most widely used SOT packages nowadays.

In electronics, packaging not only plays the role of installing, fixing, sealing, protecting chips and enhancing the electrothermal performance, but also connects the contacts on the chips to the pins of the package shell by wires. These pins are connected with other devices through wires on the printed circuit board, thus realizing the connection between the internal chip and the external circuit. Because the chip must be isolated from the outside world to prevent the corrosion of the chip circuit caused by impurities in the air, resulting in the decline of electrical performance. On the other hand, the encapsulated chip is more convenient to install and transport.

https://www.weetcl.com/Small_Signal_Transistors/WEET_Transistors_SOT-23_MMBTSC945.html

https://www.weetcl.com/pdf/WEET_Transistors_SOT-23_MMBTSC945.pdf