Orientation and Lead Numbering
As shown in the diagram, leads are numbered consecutively from Pin 1. When the identifying notch in the package is at the top, Pin 1 is the top left corner of the device. Sometimes Pin 1 is identified with an indent or paint dot mark.
For example, for a 14-lead DIP, with the notch at the top, the left leads are numbered from 1 to 7 (top to bottom) and the right row of leads are numbered 8 to 14 (bottom to top).
Some DIP devices, such as segmented LED displays, or those that replace leads with a heat sink fin, skip some leads; the remaining leads are numbered as if all positions had leads.
In addition to providing for human visual identification of the orientation of the package, the notch allows automated chip-insertion machinery to confirm correct orientation of the chip by mechanical sensing.
Read more about this topic: Dual In-line Package
Famous quotes containing the words orientation, lead and/or numbering:
“Every orientation presupposes a disorientation.”
—Hans Magnus Enzensberger (b. 1929)
“Well, the wedding is over, the good folks are joined for better for worse—a shocking clause that!—’tis preparing one to lead a long journey, and to know the path is not altogether strewed with roses.”
—Frances Burney (1752–1840)
“The task he undertakes
Is numbering sands and drinking oceans dry.”
—William Shakespeare (1564–1616)