SN74LS123 [MOTOROLA]
RETRIGGERABLE MONOSTABLE MULTIVIBRATORS; 可重触发单稳态触发器
| 型号： | SN74LS123 |
| 厂家： | 
MOTOROLA |
| 描述： | RETRIGGERABLE MONOSTABLE MULTIVIBRATORS |
| 文件： | 总10页 (文件大小：280K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SN54/74LS122
SN54/74LS123
RETRIGGERABLE MONOSTABLE
MULTIVIBRATORS
These dc triggered multivibrators feature pulse width control by three meth-
ods. The basic pulse width is programmed by selection of external resistance
and capacitance values. The LS122 has an internal timing resistor that allows
the circuits to be used with only an external capacitor. Once triggered, the ba-
sic pulse width may be extended by retriggering the gated low-level-active (A)
or high-level-active (B) inputs, or be reduced by use of the overriding clear.
RETRIGGERABLE MONOSTABLE
MULTIVIBRATORS
LOW POWER SCHOTTKY
• Overriding Clear Terminates Output Pulse
• Compensated for V
and Temperature Variations
CC
• DC Triggered from Active-High or Active-Low Gated Logic Inputs
• Retriggerable for Very Long Output Pulses, up to 100% Duty Cycle
• Internal Timing Resistors on LS122
J SUFFIX
CERAMIC
CASE 620-09
16
1
SN54/74LS123 (TOP VIEW)
(SEE NOTES 1 THRU 4)
N SUFFIX
PLASTIC
CASE 648-08
16
1
D SUFFIX
SOIC
CASE 751B-03
16
1
J SUFFIX
CERAMIC
CASE 632-08
14
1
SN54/74LS122 (TOP VIEW)
(SEE NOTES 1 THRU 4)
N SUFFIX
PLASTIC
CASE 646-06
14
1
D SUFFIX
SOIC
CASE 751A-02
14
1
NOTES:
ORDERING INFORMATION
1. An external timing capacitor may be connected between C
2. To use the internal timing resistor of the LS122, connect R to V
3. For improved pulse width accuracy connect an external resistor between R /C
and R /C (positive).
ext ext
ext
.
SN54LSXXXJ Ceramic
SN74LSXXXN Plastic
SN74LSXXXD SOIC
int CC
and
ext ext
V
with R open-circuited.
int
CC
4. To obtain variable pulse widths, connect an external variable resistance between R /C
int ext
and V
.
CC
FAST AND LS TTL DATA
5-197
SN54/74LS122 • SN54/74LS123
LS122
LS123
FUNCTIONAL TABLE
FUNCTIONAL TABLE
INPUTS
OUTPUTS
INPUTS
A
OUTPUTS
CLEAR
A1
A2
B1
B2
Q
Q
CLEAR
B
Q
Q
L
X
X
X
H
H
H
H
H
H
H
↑
X
H
X
X
L
X
H
X
X
X
X
L
L
↓
↓
X
X
L
X
↑
X
X
X
L
H
↑
L
L
L
L
H
H
H
H
L
X
X
H
H
↑
X
H
X
L
↓
L
X
X
L
↑
H
H
L
L
L
H
H
H
L
H
↑
X
X
H
↓
↓
L
H
↑
H
H
H
H
H
H
H
H
H
H
H
H
X
L
↑
X
TYPICAL APPLICATION DATA
The output pulse t is a function of the external compo-
separate power supplies are used for V
tied to V , Figure 7 shows how K will vary with V
RC
temperature. Remember, the changes in R
and V . If V
RC
is
and
with
W
CC
CC
nents,C andR orC andR ontheLS122.Forvalues
ext ext ext int
CC
ext
of C
ext
≥ 1000 pF, the output pulse at V
= 5.0 V and V
RC
=
and C
ext
CC
5.0 V (see Figures 1, 2, and 3) is given by
temperature are not calculated and included in the graph.
As long as C
(SN74LS122/123) or 5K ≤ R
ext
the change in K with respect to R
≥ 1000 pF and 5K ≤ R
≤ 260K
≤ 160 K (SN54LS122/123),
ext
ext
t
= K R where K is nominally 0.45
C
W
ext ext
If C
The C
is on pF and R is in kΩ then t is in nanoseconds.
ext
ext
W
is negligible.
ext
terminal of the LS122 and LS123 is an internal
ext
If C ≤ 1000 pF the graph shown on Figure 8 can be used
ext
connection to ground, however for the best system perfor-
mance C should be hard-wired to ground.
to determine the output pulse width. Figure 9 shows how K will
ext
changeforC ≤1000pFifV
andV
areconnectedtothe
ext
CC
RC
Care should be taken to keep R
and C as close to the
ext
monostableaspossiblewithaminimumamountofinductance
between the R /C junction and the R /C pin. Good
ext
same power supply. The pulse width t in nanoseconds is
W
approximated by
ext ext ext ext
groundplane and adequate bypassing should be designed
into the system for optimum performance to insure that no
false triggering occurs.
t
= 6 + 0.05 C
ext
(pF) + 0.45 R
ext
(kΩ) C
+ 11.6 R
ext ext
W
In order to trim the output pulse width, it is necessary to
includeavariableresistorbetweenV andtheR /C pin
or between V
and12showhowthiscanbedone.R remoteshouldbekept
ext
as close to the monostable as possible.
It should be noted that the C
pin is internally connected
ext
CC
ext ext
to ground on the LS122 and LS123, but not on the LS221.
Therefore, if C is hard-wired externally to ground, substitu-
and the R
pin of the LS122. Figure 10, 11,
CC
ext
ext
tion of a LS221 onto a LS123 socket will cause the LS221 to
become non-functional.
Retriggering of the part, as shown in Figure 3, must not
The switching diode is not needed for electrolytic capaci-
tance application and should not be used on the LS122 and
LS123.
occur before C
have any effect. The discharge time of C
ext
guaranteed to be less than 0.22 C
is discharged or the retrigger pulse will not
in nanoseconds is
(pF) and is typically 0.05
ext
ext
To find the value of K for C
≥ 1000 pF, refer to Figure 4.
C
(pF).
ext
can cause the value of K to change,
ext
For the smallest possible deviation in output pulse widths
Variationson V
or V
CC
RC
as can the temperature of the LS123, LS122. Figures 5 and
6 show the behavior of the circuit shown in Figures 1 and 2 if
from various devices, it is suggested that C
≥ 1000 pF.
be kept
ext
FAST AND LS TTL DATA
5-198
SN54/74LS122 • SN54/74LS123
GUARANTEED OPERATING RANGES
Symbol
Parameter
Min
Typ
Max
Unit
V
CC
Supply Voltage
54
74
4.5
4.75
5.0
5.0
5.5
5.25
V
T
A
Operating Ambient Temperature Range
54
74
–55
0
25
25
125
70
°C
I
I
Output Current — High
Output Current — Low
54, 74
–0.4
mA
mA
OH
54
74
4.0
8.0
OL
R
External Timing Resistance
External Capacitance
54
74
5.0
5.0
180
260
kΩ
ext
ext
C
R
54, 74
54, 74
No Restriction
50
/C
ext ext
Wiring Capacitance at R /C
ext ext
Terminal
pF
WAVEFORMS
EXTENDING PULSE WIDTH
OVERRIDING THE OUTPUT PULSE
FAST AND LS TTL DATA
5-199
SN54/74LS122 • SN54/74LS123
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified)
Limits
Min
Typ
Max
Symbol
Parameter
Input HIGH Voltage
Unit
Test Conditions
Guaranteed Input HIGH Voltage for
All Inputs
V
IH
2.0
V
54
74
0.7
0.8
Guaranteed Input LOW Voltage for
All Inputs
V
V
V
Input LOW Voltage
V
IL
Input Clamp Diode Voltage
Output HIGH Voltage
–0.65
3.5
–1.5
V
V
V
V
V
= MIN, I = –18 mA
IN
IK
CC
54
74
2.5
2.7
= MIN, I
OH
= MAX, V = V
IN
CC
IH
OH
or V per Truth Table
IL
3.5
V
V
= V
CC
MIN,
= V or V
IL IH
54, 74
74
0.25
0.35
0.4
0.5
V
V
I
I
= 4.0 mA
= 8.0 mA
CC
IN
OL
V
Output LOW Voltage
Input HIGH Current
OL
per Truth Table
OL
20
0.1
µA
mA
mA
mA
V
V
V
V
= MAX, V = 2.7 V
IN
CC
CC
CC
CC
I
IH
= MAX, V = 7.0 V
IN
I
I
Input LOW Current
–0.4
–100
11
= MAX, V = 0.4 V
IN
IL
Short Circuit Current (Note 1)
–20
= MAX
OS
LS122
LS123
I
Power Supply Current
mA
V
= MAX
CC
CC
20
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS (T = 25°C, V
CC
= 5.0 V)
A
Limits
Typ
23
Min
Max
33
Symbol
Parameter
Unit
Test Conditions
t
t
Propagation Delay, A to Q
Propagation Delay, A to Q
PLH
PHL
ns
32
45
C
C
= 0
ext
L
= 15 pF
23
44
t
t
Propagation Delay, B to Q
Propagation Delay, B to Q
PLH
PHL
ns
ns
34
56
R
R
= 5.0 kΩ
= 2.0 kΩ
ext
L
28
45
t
t
Propagation Delay, Clear to Q
Propagation Delay, Clear to Q
PLH
PHL
20
27
t
t
A or B to Q
A to B to Q
116
4.5
200
5.0
ns
W min
C
C
= 1000 pF, R
= 10 kΩ,
ext
L
ext
= 15 pF, R = 2.0 kΩ
L
Q
W
4.0
µs
AC SETUP REQUIREMENTS (T = 25°C, V
CC
= 5.0 V)
A
Limits
Typ
Min
Max
Symbol
Parameter
Unit
Test Conditions
t
W
Pulse Width
40
ns
FAST AND LS TTL DATA
5-200
SN54/74LS122 • SN54/74LS123
µ
µ
LS122
1/2 LS123
Ω
Ω
Figure 1
Figure 2
Figure 3
≤
≤
Figure 4
FAST AND LS TTL DATA
5-201
SN54/74LS122 • SN54/74LS123
°
°
°
°
K
K
K
°
°
°
°
°
°
°
°
°
°
°
V
V
V V
CC = RC
CC
RC
Figure 5. K versus V
CC
Figure 6. K versus V
RC
Figure 7. K versus V
and V
RC
CC
Ω
Ω
Ω
Ω
Ω
Ω
Ω
Figure 8
FAST AND LS TTL DATA
5-202
SN54/74LS122 • SN54/74LS123
°
°
°
°
°
Figure 9
Figure 10. LS123 Remote Trimming Circuit
FAST AND LS TTL DATA
5-203
SN54/74LS122 • SN54/74LS123
Figure 11. LS122 Remote Trimming Circuit Without R
ext
Figure 12. LS122 Remote Trimming Circuit with R
int
FAST AND LS TTL DATA
5-204
Case 751B-03 D Suffix
16-Pin Plastic
SO-16
-A-
16
1
9
8
P
C
-B-
R X 45°
G
-T-
J
M
F
D
°
°
°
°
K
Case 648-08 N Suffix
16-Pin Plastic
-A-
16
1
9
B
S
8
F
L
C
K
-T-
M
H
J
G
D
°
°
°
°
Case 620-09 J Suffix
16-Pin Ceramic Dual In-Line
-A-
16
9
-B-
1
8
L
C
-T-
K
M
N
E
J
F
G
D
°
°
°
°
FAST AND LS TTL DATA
5-205
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the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit,
andspecifically disclaims any and all liability, includingwithoutlimitationconsequentialorincidentaldamages. “Typical” parameters can and do vary in different
applications. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. Motorola does
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associated with such unintended or unauthorized use, even if such claim alleges that Motorola was negligent regarding the design or manufacture of the part.
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◊
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