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SN54ALS160B THRU SN54ALS163B, SN54AS160 THRU SN54AS163
SN74ALS160B THRU SN74ALS163B, SN74AS160 THRU SN74AS163
SYNCHRONOUS 4 BIT DECADE AND BINARY COUNTERS
•
•
•
•
•
•
Internal Look-Ahead for Fast Counting
Carry Output for n-Bit Cascading
Synchronous Counting
Synchronously Programmable
Package Options include Plastic Small
Outline Packages, Ceramic Chip Carriers,
and Standard Plastic and Ceramic 300-mil
DIPs
Dependable Texas Instruments Quality and
Reliability
SN54ALS’, SN54AS’ . . . J PACKAGE
SN74ALS’, SN74AS’ . . . D OR N PACKAGE
(TOP VIEW)
SDAS024A − D2661, APRIL 1982 − REVISED MAY 1986
CLR
CLK
A
B
C
D
ENP
GND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
CC
RCO
Q
A
Q
B
Q
C
Q
D
ENT
LOAD
description
These synchronous, presettable counters feature
an internal carry look-ahead for application in
high-speed counting designs. The ’ALS160B,
’ALS162B, ’AS160, and ’AS162 are decade
counters, and the ’ALS161B, ’ALS163B, ’AS161,
and ’AS163 are 4-bit binary counters. Synchro-
nous operation is provided by having all flip-flops
clocked simultaneously so that the outputs
change coincident with each other when so
instructed by the count-enable inputs and internal
gating. This mode of operation eliminates the
output counting spikes that are normally asso-
ciated with asynchronous (ripple clock)
counters. A buffered clock input triggers the four
flip-flops on the rising (positive-going) edge of the
clock input waveform.
SN54ALS’, SN54AS’ . . . FK PACKAGE
(TOP VIEW)
A
B
NC
C
D
4
5
6
7
8
3 2 1 20 19
18
17
16
15
14
9 10 11 12 13
CLK
CLR
NC
VCC
RCO
Q
A
Q
B
NC
Q
C
Q
D
NC−No internal connection
Copyright
1986, Texas Instruments Incorporated
5BASIC
These counters are fully programmable; that is, they may be preset to any number between 0 and 9, or 15. As
presetting is synchronous, 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 for the ’ALS160B, ’ALS161B, ’AS160, and ’AS161 is asynchronous and a low level at the clear
input sets all four of the flip-flop outputs low regardless of the levels of the clock, load, or enable inputs. This
synchronous clear allows the count length to be modified easily by decoding the Q outputs for the maximum
count desired. The active-low output of the gate used for decoding is connected to the clear input to
synchronously clear the counter to 0000 (LLLL).
The carry look-ahead circuitry provides for cascading counters for n-bit synchronous applications without
additional gating. Instrumental in accomplishing this function are two count-enable inputs and a ripple carry
output. Both count-enable inputs (ENP and ENT) must be high to count, and ENT is fed forward to enable the
ripple carry output. The ripple carry output (RCO) thus enabled will produce 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 the ENP or ENT are allowed regardless of the level of the clock input.
These counters feature a fully independent clock circuit. Changes at control inputs (ENP, ENT, or LOAD) that
will 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) will be dictated solely by the conditions meeting
the stable setup and hold times.
The SN54ALS160B through SN54ALS163B and SN54AS160 through SN54AS163 are characterized for
operation over the full military temperature range of − 55°C to 125°C. The SN74ALS160B through
SN74ALS163B and SN74AS160 through SN74AS163 are characterized for operation from 0°C to 70°C.
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
POST OFFICE BOX 1443 HOUSTON, TEXAS 77001
•
•
ENP
GND
NC
LOAD
ENT
1
SDAS024A − D2661, APRIL 1982 − REVISED MAY 1986
SN54ALS160B, SN54ALS162B, SN54AS160, SN54AS162
SN74ALS160B, SN74ALS162B, SN74AS160, SN74AS162
SYNCHRONOUS 4 BIT BINARY COUNTERS
logic symbols
†
’ALS160B AND ’AS160 BINARY
COUNTERS WITH DIRECT CLEAR
CTRDIV10
CLR
LOAD
1
9
CT=0
M1
M2
ENT
ENP
CLK
A
B
C
D
10
7
2
3
4
5
6
G3
G4
C5/2,3,4+
1,5D
[1]
[2]
[4]
[8]
14
13
12
11
QA
QB
QC
QD
3CT = 9
15
RCO
ENT
ENP
CLK
A
B
C
D
CLR
LOAD
1
9
M1
M2
10
7
2
3
4
5
6
G3
G4
C5/2,3,4+
1,5D
[1]
[2]
[4]
[8]
14
13
12
11
QA
QB
QC
QD
3CT = 9
15
RCO
’ALS162B AND ’AS162 BINARY
COUNTERS WITH SYNCHRONOUS CLEAR
CTRDIV10
5CT=0
’ALS160B and ’AS160 logic diagram (positive logic)
1
CLR
9
LOAD
10
ENT
7
ENP
2
C1
1D
R
A
3
14
QA
15
RCO
CLK
C1
1D
R
B
4
13
QB
C
5
C1
1D
R
12
QC
C1
1D
R
D
6
11
QD
† These symbols are in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
Pin numbers shown are for D, J, and N packages.
’ALS162B and ’AS162 decade counters are similar; however the clear is synchronous as shown for the ’ALS163B and ’AS163 binary counters.
2
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
POST OFFICE BOX 1443 HOUSTON, TEXAS 77001
•
•
SN54ALS161B, SN54ALS163B, SN54AS161, SN54AS163
SN74ALS161B, SN74ALS163B, SN74AS161, SN74AS163
SYNCHRONOUS 4 BIT BINARY COUNTERS
SDAS024A − D2661, APRIL 1982 − REVISED MAY 1986
logic symbols
†
’ALS161B AND ’AS161 BINARY
COUNTERS WITH DIRECT CLEAR
CTRDIV16
CLR
LOAD
1
9
CT=0
M1
M2
ENT
ENP
CLK
A
B
C
D
10
7
2
3
4
5
6
G3
G4
C5/2,3,4+
1,5D [1]
[2]
[4]
[8]
14
13
12
11
QA
QB
QC
QD
3CT = 15
15
RCO
ENT
ENP
CLK
A
B
C
D
CLR
LOAD
1
9
M1
M2
10
7
2
3
4
5
6
G3
G4
C5/2,3,4+
1,5D [1]
[2]
[4]
[8]
14
13
12
11
QA
QB
QC
QD
3CT = 15
15
RCO
’ALS163B AND ’AS163 BINARY
COUNTERS WITH SYNCHRONOUS CLEAR
CTRDIV16
5CT=0
’ALS163B and ’AS163 logic diagram (positive logic)
CLR
LOAD
ENT
ENP
1
9
10
7
15
RCO
CLK
2
C1
1D
3
14
QA
A
C1
1D
B
4
13
QB
C1
1D
C
5
12
QC
C1
1D
D
6
11
QD
† These symbols are in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
Pin numbers shown are for D, J, and N packages.
’ALS161B and ’AS161 synchronous binary counters are similar; however the clear is asynchronous as shown for the ’ALS160B and ’AS160 decade
counters.
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
POST OFFICE BOX 1443 HOUSTON, TEXAS 77001
•
•
3
SDAS024A − D2661, APRIL 1982 − REVISED MAY 1986
SN54ALS160B, SN54ALS162B, SN54AS160, SN54AS162
SN74ALS160B, SN74ALS162B, SN74AS160, SN74AS162
SYNCHRONOUS 4 BIT DECADE COUNTERS
typical clear, preset, count, and inhibit sequences
’ALS160B, ’AS160, ’ALS162B, ’AS162
Illustrated below is the following sequence:
1. Clear outputs to zero (’ALS160B and ’AS160 are asynchronous; ’ALS162B and ’AS1162 are synchronous)
2. Preset to BCD seven
3. Count to eight, nine, zero, one, two, and three
4. Inhibit
CLR
LOAD
A
B
Data
Inputs
C
D
CLK
ENP
ENT
QA
QB
Outputs
QC
QD
RCO
7
8
9
0
1
Count
Sync Preset
Clear
2
3
Inhibit
Async
Clear
4
POST OFFICE BOX 655303 DALLAS, TEXAS 75265
POST OFFICE BOX 1443 HOUSTON, TEXAS 77001
•
•
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