LSI DIGITAL CLOCK
The LSI clock chip forms the heart of modern digital timepieces. These digital clock chips are made as monolithic MOS ICs. Many a times, the MOS LSI chip, or die, is mounted directly on the PC board of a clock module. The tiny silicon die is sealed under an epoxy coating. Examples of the two packaging methods are shown in Fig. 47.5. An MOS LSI clock IC packaged in a 24 pin DIP is shown in Fig. 47.5 (a). Pin 1 of the IC is identified in the normal manner (pin 1 is immediately counter clockwise from the notch). A National semiconductor clock module is sketched in Fig. 47.5 (b). The back is a PC board with 22 edge connectors.
The numbering of the edge connectors is shown. A four digit LED display is premounted on the board with ...
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