Texas Instruments SN74ALS561ADW, SN74ALS561ADWR, SN74ALS561AN, SNJ54ALS561AJ Datasheet
SN54ALS561A, SN74ALS561A
SYNCHRONOUS 4-BIT COUNTERS
WITH 3-STATE OUTPUTS
SDAS225A – DECEMBER 1982 – REVISED JANUARY 1995
Copyright 1995, Texas Instruments Incorporated
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
• Carry Output for n-Bit Cascading
• Buffer-Type Outputs Drive Bus Lines
Directly
• Choice of Asynchronous or Synchronous
Clearing and Loading
• Internal Look-Ahead Circuitry for Fast
Cascading
• Package Options Include Plastic
Small-Outline (DW) Packages, Ceramic
Chip Carriers (FK), and Standard Plastic (N)
and Ceramic (J) 300-mil DIPs
description
These binary counters are programmable and
offer synchronous and asynchronous clearing as
well as synchronous and asynchronous loading.
All synchronous functions are executed on the
positive-going edge of the clock.
The clear function is initiated by applying a low
level to either asynchronous clear (ACLR
) or
synchronous clear (SCLR
). ACLR (direct clear)
overrides all other functions of the device, while
SCLR
overrides only the other synchronous
functions. Data is loaded from the A, B, C, and D
inputs by applying a low level to asynchronous
load (ALOAD
) or by the combination of a low level
at synchronous load (SLOAD
) and a
positive-going clock transition. The counting
function is enabled only when enable P (ENP),
enable T (ENT), ACLR
, ALOAD, SCLR, and
SLOAD
are all high.
A high level at the output-enable (OE
) input forces the Q outputs into the high-impedance state, and a low level
enables those outputs. Counting is independent of OE
. ENT is fed forward to enable the ripple-carry output
(RCO) to produce a high-level pulse while the count is maximum (15). The clocked carry output (CCO) produces
a high-level pulse for a duration equal to that of the low level of the clock when RCO is high and the counter is
enabled (ENP and ENT are high); otherwise, CCO is low. CCO does not have the glitches commonly associated
with a ripple-carry output. Cascading is normally accomplished by connecting RCO or CCO of the first counter
to ENT of the next counter. However , for very high-speed counting, RCO should be used for cascading because
CCO does not become active until the clock returns to the low level.
The SN54ALS561A is characterized for operation over the full military temperature range of –55°C to 125°C.
The SN74ALS561A is characterized for operation from 0°C to 70°C.
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
ALOAD
CLK
A
B
C
D
ENP
ACLR
SCLR
GND
V
CC
RCO
CCO
OE
Q
A
Q
B
Q
C
Q
D
ENT
SLOAD
SN54ALS561A ...J PACKAGE
SN74ALS561A . . . DW OR N PACKAGE
(TOP VIEW)
3212019
910111213
4
5
6
7
8
18
17
16
15
14
CCO
OE
Q
A
Q
B
Q
C
B
C
D
ENP
ACLR
A
CLK
ALOAD
ENT
Q
RCO
SCLR
GND
SLOAD
V
CC
SN54ALS561A . . . FK PACKAGE
(TOP VIEW)
D
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.
SN54ALS561A, SN74ALS561A
SYNCHRONOUS 4-BIT COUNTERS
WITH 3-STATE OUTPUTS
SDAS225A – DECEMBER 1982 – REVISED JANUAR Y 1995
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
FUNCTION TABLE
INPUTS
OE ACLR ALOAD SCLR SLOAD ENT ENP CLK
OPERATION
H X X X X X X X Q outputs disabled
L L X X X X X X Asynchronous clear
L H L X X X X X Asynchronous load
L HHLXXX↑Synchronous clear
L HHHLXX↑Synchronous load
L HHHHHH↑ Count
L H H H H L X X Inhibit counting
L H H H H X L X Inhibit counting
logic symbol
†
CTRDIV16
C8
1
2
CLK
4,6D/8D
3
A
4
B
5
C
6
D
C6/1, 2, 3, 5+
M5 [COUNT]
Z7
CCO
18
7, 1, 2, 9
RCO
19
1 (CT=15) G9
16
15
14
13
CT=0
8
M4 [SYNC LOAD]
11
M3 [COUNT]
6CT=0 [SYNC CLR]
9
G2
7
ENP
G1
12
ENT
EN10
17
10
OE
SCLR
SLOAD
ACLR
ALOAD
Q
A
Q
B
Q
C
Q
D
†
This symbol is in accordance with ANSI/IEEE Std 91-1984 and IEC Publication 617-12.
SN54ALS561A, SN74ALS561A
SYNCHRONOUS 4-BIT COUNTERS
WITH 3-STATE OUTPUTS
SDAS225A – DECEMBER 1982 – REVISED JANUARY 1995
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
logic diagram (positive logic)
R
S
1D
C1
R
S
1D
C1
R
S
1D
C1
R
S
1D
C1
17
12
7
9
11
2
8
1
3
4
5
6
18
19
16
15
14
13
CCO
RCO
Q
A
Q
B
Q
C
Q
D
OE
ENT
ENP
SCLR
SLOAD
CLK
ACLR
ALOAD
A
B
C
D
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