1

36-00-04-001

Ver. 1.0.0

Aeroflex Microelectronics Solutions - HiRel

UT54ACS191E

Synchronous 4-Bit Up-Down Binary Counters

March 2015

www.aeroflex.com/Logic

Datasheet

FEATURES

• Single down/up count control line

• Look-ahead circuitry enhances speed of cascaded counters

• Fully synchronous in count modes

• Asynchronously pre-settable with load control

•0.6μm CRH CMOS process

- Latchup immune

• High speed

• Low power consumption

• Wide power supply operating range of 3.0V to 5.5V

• Available QML Q or V processes

• 16-lead flatpack

• UT54ACS191E - SMD 5962-96564

DESCRIPTION

The UT54ACS191E is a performance and voltage enhanced

version of the UT54ACS191 synchronous 4-bit, reversible up-

down binary 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. Synchronous operation eliminates the output

counting spikes associated with asynchronous counters.

The outputs of the four flip-flops are triggered on a low-to-high-

level transition of the clock input if the enable input (CTEN) is

low. A logic one applied to CTEN inhibits counting. The direc-

tion of the count is determined by the level of the down/up (D/

U) input. When D/U is low, the counter counts up and when D/

U is high, it counts down.

The counter features a fully independant clock circuit. Changes

at control inputs (CTEN and D/U) that will modify the operating

mode have no effect on the contents of the counter until clocking

occcurs.

The counter is fully programmable. The outputs may be preset

to either logic level by placing a low on the load input and

entering the desired data at the data inputs. The output will

change to agree with the data inputs independently of the level

of the clock input. The asynchronous load allows counters to

be used as modulo-N dividers 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 (MAX/MIN)

count. The MAX/MIN 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 (RCO) produces a low-level output

pulse under those same conditions but only while the clock input

is low. The counters easily cascade by feeding the RCO to the

enable input of the succeeding counter if parallel clocking is

used, or to the clock input if parallel enabling is used. Use the

MAX/MIN count output to accomplish look-ahead for high-

speed operation.

The device is characterized over full military temperature range

PINOUT

16-Lead Flatpack

TopView

FUNCTION TABLE

FUNCTION

LOAD

CTEN

D/U

CLK

Count Up

H

L

L

-

Count Down

H

L

H

-

Asynchronous

Reset

L

X

X

X

No Change

H

H

X

X

1

2

3

4

5

7

6

16

15

14

13

12

10

11

89

B

CTEN

D/U

A

CLK

RCO

LOAD

C

D

MAX/MIN