74ACT11191

SYNCHRONOUS 4BIT UP/DOWN BINARY COUNTER

SCAS106A − D3455, FEBRUARY 1990 − REVISED APRIL 1993

POST OFFICE BOX 655303

POST OFFICE BOX 1443

2−2

description (continued)

These counters are fully programmable; that is, they may be preset to any number between 0 and 15 by placing

a low on the load input and entering the desired data at the data inputs. The outputs will change to agree with

the data inputs independently of the level of the clock input. This feature allows the counter to be used as a

modulo-N divider by simply modifying the count length with the preset inputs.

Two outputs have been made available to perform the cascading function: ripple clock and maximum/minimum

count. The latter output produces a high-level output pulse with a duration approximately equal to one complete

cycle of the clock while the count is zero (all outputs low) counting down or maximum (15) counting up. The

ripple clock output (ROC) produces a low-level output pulse under those same conditions but only while the

clock input is low. The counter can easily be cascaded by feeding the ripple clock output to the enable input

of the succeeding counter if parallel clocking is used, or to the clock input if parallel enabling is used. The

maximum/minimum count output can be used to accomplish look-ahead for high-speed operation.

The 74ACT11191 is characterized for operation from − 40

°C to 85°C.