74HC4059 datasheet(13/20 Pages) PHILIPS

13 / 20 page

1998 Jul 08

Philips Semiconductors

Product speciﬁcation

Programmable divide-by-n counter

74HC/HCT4059

The arrangement shown in Fig.12 is easy to follow; once

during every cycle the programmed digits are jammed in

(15 616 in this example) and then a round number of

11 000 is jammed in, nine times in succession, by forcing

the JAM inputs via AND/OR gates.

Numbers larger than the extended counter range can also

be produced by cascading the PC74HC/HCT4059 with

some other counting devices. Figure 13 shows such an

arrangement where only one fixed divide-by number is

desired. The dual flip-flop wired to produce a divide-by-3

count can be replaced by other counters such as the “190”,

“191”, “192”, “193”, “4017”, “4510” and “4516”.

In Fig.13 the divide-by-n sub-system is preset once to a

number which represents the least significant digits of the

divide-by number (15 690 in the example shown in Fig.13).

The sub-system is then preset twice to a round number

(8 000 in the example shown in Fig.13) and multiplied by

the number of the divide-by mode (2 in the example shown

in Fig.13).

To verify:

15 690

+ 2 × 8 000 × 2 = 47 690.

It is important that the second counting device has an

output that is HIGH or LOW during only one of its counting

states.

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