1-27
Figure 1-29.—J-K flip-flop discrete component and an IC.
IC PACKAGE LEAD IDENTIFICATION (NUMBERING)
When you look at an IC package you should notice that the IC could be connected incorrectly into a
circuit. Such improper replacement of a component would likely result in damage to the equipment. For
this reason, each IC has a REFERENCE MARK to align the component for placement. The dual inline
package (both plastic and ceramic) and the flat pack have a notch, dot, or impression on the package.
When the package is viewed from the top, pin 1 will be the first pin in the counterclockwise direction next
to the reference mark. Pin 1 may also be marked directly by a hole or notch or by a tab on it (in this case
pin 1 is the counting reference). When the package is viewed from the top, all other pins are numbered
consecutively in a counterclockwise direction from pin 1, as shown in figure 1-30, views (A) and (B).
