m Process
m Process
EPIC is a trademark of Texas Instruments Incorporated.
The 'ACT11190 is a synchronous, 4-bit decade reversable up/down
counter. Synchronous counting operation is provided by having all
flip-flops clocked simultaneously so that the outputs change
coincident with each other when so instructed by the steering
logic.This mode of operation eliminates the output counting spikes
normally associated with asynchronous
(ripple-clock) counters.
The outputs of the four flip-flops are triggered on a low-to-high
transition of the clock input if the enable input (
) is low. A high at inhibits counting. The direction
of the count is determined by the level of the down/up (D/U\) input.
When the D/U\ input is low, the counter counts up. When the D/U\
input is high, the counter counts down.
These counters feature a fully independent clock circuit. Changes
at control inputs ( and
D/U\) that will modify the operating mode have no effect on the
contents of the counter until clocking occurs. The function of the
counter is dictated solely by the condition meeting the stable setup
and hold times.
These counters are fully programmable; that is, it may be preset to any number between 0 and 9 by placing a low on the load input and entering the desired data at the data inputs. The outputs change to agree with the data inputs independently of the level of the clock input. This feature allows the counter to be used as modulo-N dividers by modifying the count length with the preset inputs.
Two outputs have been made available to perform the cascading
function: 
and MAX/MIN
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 (9)
counting up. The () produces a
low-level output pulse under those same conditions but only while the
clock input is low. The counter can 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 MAX/MIN count output can be used to accomplish
look-ahead for high-speed operation.
The 54ACT11190 is characterized for operation over the full military temperature range of - 55°C to 125°C. The 74ACT11190 is characterized for operation from - 40°C to 85°C.