CD54AC161 Datasheet, PDF (1/15 Pages) Texas Instruments – 4-BIT SYNCHRONOUS BINARY COUNTERS

CD54AC161, CD74AC161
4-BIT SYNCHRONOUS BINARY COUNTERS
SCHS239C – SEPTEMBER 1998 – REVISED MARCH 2003
D Internal Look-Ahead for Fast Counting
D Carry Output for n-Bit Cascading
D Synchronous Counting
D Synchronously Programmable
D SCR-Latchup-Resistant CMOS Process and
Circuit Design
D Exceeds 2-kV ESD Protection per
MIL-STD-883, Method 3015
description/ordering information
CD54AC161 . . . F PACKAGE
CD74AC161 . . . E OR M PACKAGE
(TOP VIEW)
CLR 1
CLK 2
A3
B4
C5
D6
ENP 7
GND 8
16 V_CC
15 RCO
14 Q_A
13 Q_B
12 Q_C
11 Q_D
10 ENT
9 LOAD
The ’AC161 devices are 4-bit binary counters.
These synchronous, presettable counters feature
an internal carry look-ahead for application in
high-speed counting These devices are fully programmable; that is, they can be preset to any number between
0 and 9 or 15. Presetting is synchronous; therefore, setting up a low level at the load input disables the counter
and causes the outputs to agree with the setup data after the next clock pulse, regardless of the levels of the
enable inputs.
The clear function is asynchronous. A low level at the clear (CLR) input sets all four of the flip-flop outputs low,
regardless of the levels of the CLK, load (LOAD), or enable inputs.
The carry look-ahead circuitry provides for cascading counters for n-bit synchronous applications without
additional gating. Instrumental in accomplishing this function are ENP, ENT, and a ripple-carry output (RCO).
Both ENP and ENT must be high to count, and ENT is fed forward to enable RCO. Enabling RCO produces a
high-level pulse while the count is maximum (9 or 15, with Q_A high). This high-level overflow ripple-carry pulse
can be used to enable successive cascaded stages. Transitions at ENP or ENT are allowed, regardless of the
level of CLK.
The counters feature a fully independent clock circuit. Changes at control inputs (ENP, ENT, or LOAD) that
modify the operating mode have no effect on the contents of the counter until clocking occurs. The function of
the counter (whether enabled, disabled, loading, or counting) is dictated solely by the conditions meeting the
stable setup and hold times.
ORDERING INFORMATION
TA
PACKAGE†
ORDERABLE
PART NUMBER
TOP-SIDE
MARKING
PDIP – E Tube
CD74AC161E
CD74AC161E
Tube
–55°C to 125°C SOIC – M
Tape and reel
CD74AC161M
AC161M
CD74AC161M96
CDIP – F Tube
CD54AC161F3A CD54AC161F3A
† _{Package drawings, standard packing quantities, thermal data, symbolization, and PCB}
design guidelines are available at www.ti.com/sc/package.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
• POST OFFICE BOX 655303 DALLAS, TEXAS 75265
Copyright  2003, Texas Instruments Incorporated
On products compliant to MIL-PRF-38535, all parameters are tested
unless otherwise noted. On all other products, production
processing does not necessarily include testing of all parameters.
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