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Wednesday, February 4, 2009

How to identify the pin number on SMD packages?

Author: Chaonan Chen, Au Group Electronics
The article used some components from Au Group Electronics BB0703 to illustrate how to identify the first pin or the pin polarity for SMD chips, capacitors, LED, and diodes etc.

U1 is PIC18F2550, there is a "dot" mark on the chip and pin 1 is on the left side of the mark.

U3 and U4 are 24LC512 EEPROM, identify the "dot" mark on the chip, and pin 1 is located on the left side of the mark.

U5 is LM317L, U6 is FDC6420C, both chip has a "dot" mark next to the pin 1.

C15 is an aluminum electrolytic capacitor, there is a black mark on the top of the capacitor which represents the "negative side" of the capacitor.

C5, C12 and C14 are tantalum capacitors, the black mark on the top of the capacitor package represents the anode (positive termination) of the capacitor.

The SMD LEDs have a color make on the cathode (Negative termination).
The through hole type LED has a shorter pin which represents cathode (negative termination).

D5 is diode S1G, which has a mark on the cathode (Negative termination).

D100 is 1N4148, which has a mark on the cathode (Negative termination).

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