SYNCHRONOUS 4-BIT UP/DOWN COUNTER

SN74LS669
SYNCHRONOUS 4-BIT
UP/DOWN COUNTER
The SN54/74LS669 is a synchronous 4-bit up/down counter. The
LS669 is a 4-bit binary counter. For high speed counting applications,
this presettable counter features an internal carry lookahead for
cascading purposes. By clocking all flip-flops simultaneously so the
outputs change coincident with each other (when instructed to do so by
the count enable inputs and internal gating) synchronous operation is
provided. This helps to eliminate output counting spikes, normally
associated with asynchronous (ripple-clock) counters. The four
master-slave flip-flops are triggered on the rising (positive-going)
edge of the clock waveform by a buffered clock input.
Circuitry of the load inputs allows loading with the carry-enable
output of the cascaded counters. Because loading is synchronous,
disabling of the counter by setting up a low level on the load input will
cause the outputs to agree with the data inputs after the next clock
pulse.
Cascading counters for N-bit synchronous applications are provided
by the carry look-ahead circuitry, without additional gating. Two
count-enable inputs and a carry output help accomplish this function.
Count-enable inputs (P and T) must both be low to count. The level of
the up-down input determines the direction of the count. When the
input level is low, the counter counts down, and when the input is high,
the count is up. Input T is fed forward to enable the carry output. The
carry output will now produce a low level output pulse with a duration
9 equal to the high portion of the QA output when counting up and
when counting down 9 equal to the low portion of the QA output. This
low level carry pulse may be utilized to enable successive cascaded
stages. Regardless of the level of the clock input, transitions at the P or
T inputs are allowed. By diode-clamping all inputs, transmission line
effects are minimized which allows simplification of system design.
Any changes at control inputs (ENABLE P, ENABLE T, LOAD,
UP/DOWN) will have no effect on the operating mode until clocking
occurs because of the fully independant clock circuits. Whether
enabled, disabled, loading or counting, the function of the counter is
dictated entirely by the conditions meeting the stable setup and hold
times.
• Programmable Look-Ahead Up/Down Binary/Decade Counters
• Fully Synchronous Operation for Counting and Programming
• Internal Look-Ahead for Fast Counting
• Carry Output for n-Bit Cascading
• Fully Independent Clock Circuit
• Buffered Outputs
© Semiconductor Components Industries, LLC, 2006
July, 2006 − Rev. 6
1
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SYNCHRONOUS 4-BIT
UP/DOWN COUNTER
LOW POWER SCHOTTKY
16
J SUFFIX
CERAMIC
CASE 620-09
1
N SUFFIX
PLASTIC
CASE 648-08
16
1
16
1
D SUFFIX
SOIC
CASE 751B-03
ORDERING INFORMATION
SN54LSXXXJ
SN74LSXXXN
SN74LSXXXD
Ceramic
Plastic
SOIC
Publication Order Number:
SN74LS669/D
SN74LS669
CONNECTION DIAGRAM (TOP VIEW)
OUTPUTS
RIPPLE
CARRY
OUTPUT
VCC
16
15
RIPPLE
CARRY
OUTPUT
QB
QC
QD
14
13
12
11
10
QA
QB
QC
QD
ENABLE
T
LOAD
9
LOAD
UP/DOWN
1
U/D
ENABLE
T
QA
ENABLE
P
CK
A
B
C
D
2
CK
3
A
4
B
5
C
6
D
7
ENABLE
P
8
GND
DATA INPUTS
LOGIC DIAGRAM
(3)
DATA
(4)
DATA
(5)
DATA
(6)
DATA
P0
P1
P2
P3
(9) LOAD
(7) ENP
(10) ENT
(1) U/D
RCO (15)
(RIPPLE CARRY
OUTPUT)
CP
(2)
CP
D
CP
D
QA
(14)
QB
(13)
CP
D
CP
QC
(12)
D
QD
(11)
GUARANTEED OPERATING RANGES
Min
Typ
Max
Unit
VCC
Symbol
Supply Voltage
Parameter
54
74
4.5
4.75
5.0
5.0
5.5
5.25
V
TA
Operating Ambient Temperature Range
54
74
−55
0
25
25
125
70
°C
IOH
Output Current — High
54, 74
−0.4
mA
IOL
Output Current — Low
54
74
4.0
8.0
mA
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2
SN74LS669
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Limits
Symbol
VIH
Input HIGH Voltage
VIL
Input LOW Voltage
VIK
Input Clamp Diode Voltage
VOH
Output HIGH Voltage
VOL
Output LOW Voltage
IIH
Min
Parameter
Input HIGH Current
IIL
Input LOW Current
IOS
Short Circuit Current (Note 1)
ICC
Power Supply Current
Typ
Max
2.0
54
0.7
74
0.8
−0.65
−1.5
Unit
Test Conditions
V
Guaranteed Input HIGH Voltage for
All Inputs
V
Guaranteed Input LOW Voltage for
All Inputs
V
VCC = MIN, IIN = − 18 mA
54
2.5
3.5
V
74
2.7
3.5
V
VCC = MIN, IOH = MAX, VIN = VIH
or VIL per Truth Table
54, 74
0.25
0.4
V
IOL = 4.0 mA
74
0.35
0.5
V
IOL = 8.0 mA
Others
20
μA
Enable T
40
μA
Others
0.1
mA
Enable T
0.2
mA
Others
−0.4
mA
Enable T
−0.8
mA
−100
mA
VCC = MAX
34
mA
VCC = MAX
Max
Unit
−20
VCC = VCC MIN,
VIN = VIL or VIH
per Truth Table
VCC = MAX, VIN = 2.7 V
VCC = MAX, VIN = 7.0 V
VCC = MAX, VIN = 0.4 V
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS (TA = 25°C, VCC = 5.0 V)
Limits
Symbol
Parameter
Min
Typ
25
32
fMAX
Maximum Clock Frequency
tPLH
tPHL
Propagation Delay,
Clock to RCO
26
40
40
60
ns
tPLH
tPHL
Propagation Delay,
Clock to Any Q
18
18
27
27
ns
tPLH
tPHL
Enable to RCO
11
29
17
45
ns
tPLH
tPHL
U/D to RCO
22
26
35
40
ns
Max
Unit
Test Conditions
MHz
CL = 15 pF
AC SETUP REQUIREMENTS (TA = 25°C)
Limits
Symbol
Parameter
Min
Typ
tW
Clock Pulse Width
20
ns
ts
Data Setup Time
20
ns
ts
Enable Setup Time
35
ns
ts
Load Setup Time
25
ns
ts
U/D Setup Time
30
ns
th
Hold Time, Any Input
0
ns
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3
Test Conditions
VCC = 5.0 V
SN74LS669
PARAMETER MEASUREMENT INFORMATION
tw(clock)
CLOCK
INPUT
tw(clock)
3V
1.3 V
1.3 V
1.3 V
1.3 V
1.3 V
0V
ts
LOAD
INPUT
ts
th
1.3 V
3V
1.3 V
0V
ts
th
3V
DATA INPUTS
A,B,C, and D
1.3 V
1.3 V
0V
ts
th
1.3 V
ENABLE P or
ENABLE T
0V
1.3 V
3V
ts
1.3 V
UP/DOWN
INPUT
ts
th
1.3 V
th
1.3 V
3V
1.3 V
0V
VOLTAGE WAVEFORMS
3V
ENABLE T
INPUT
1.3 V
1.3 V
0V
tPHL
RIPPLE
CARRY
OUTPUT
tPLH
VOL
1.3 V
1.3 V
VOH
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SN74LS669/D