January 1988
MM54HC192/MM74HC192
Synchronous Decade Up/Down Counters
MM54HC193/MM74HC193
Synchronous Binary Up/Down Counters
General Description
These high speed synchronous counters utilize advanced
silicon-gate CMOS technology to achieve the high noise im-
munity and low power consumption of CMOS technology,
along with the speeds of low power Schottky TTL. The
MM54HC192/MM74HC192 is a decade counter, and the
MM54HC193/MM74HC193 is a binary counter. Both coun-
ters have two separate clock inputs, an UP COUNT input
and a DOWN COUNT input. All outputs of the flip-flops are
simultaneously triggered on the low to high transition of ei-
ther clock while the other input is held high. The direction of
counting is determined by which input is clocked.
Both a BORROW and CARRY output are provided to en-
able cascading of both up and down counting functions. The
BORROW output produces a negative going pulse when the
counter underflows and the CARRY outputs a pulse when
the counter overflows. The counters can be cascaded by
connecting the CARRY and BORROW outputs of one de-
vice to the COUNT UP and COUNT DOWN inputs, respec-
tively, of the next device.
All inputs are protected from damage due to static dis-
charge by diodes to V
and ground.
CC
These counters may be preset by entering the desired data
on the DATA A, DATA B, DATA C, and DATA D inputs.
When the LOAD input is taken low the data is loaded inde-
pendently of either clock input. This feature allows the count-
ers to be used as divide-by-n counters by modifying the
count length with the preset inputs.
Features
Y
Typical propagation delay,
Count up to Q: 28 ns
Y
Y
Y
Typical operating frequency: 27 MHz
Wide power supply range: 2–6V
Low quiescent supply current: 80 mA maximum
(74HC Series)
In addition both counters can also be cleared. This is ac-
complished by inputting a high on the CLEAR input. All 4
internal stages are set to a low level independently of either
COUNT input.
Y
Y
Low input current: 1 mA maximum
4 mA output drive
Connection Diagram
Truth Table
Count
Dual-In-Line Package
Clear
Load
Function
Up
Down
H
u
X
L
L
H
H
X
L
Count Up
Count Down
Clear
u
H
X
H
L
X
X
Load
e
e
H
L
high level
low level
e
transition from low-to-high
u
X
e
don’t care
TL/F/5011–1
Order Number MM54HC192/193 or MM74HC192/193
C
1995 National Semiconductor Corporation
TL/F/5011
RRD-B30M115/Printed in U. S. A.