Semiconductor Components Industries, LLC, 1999
December, 1999 Rev. 6
1
Publication Order Number:
SN74LS122/D
SN74LS122 SN74LS123
Retriggerable Monostable
Multivibrators
These dc triggered multivibrators feature pulse width control by
three methods. 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 basic 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.
Overriding Clear Terminates Output Pulse
Compensated for V
CC
and Temperature Variations
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
GUARANTEED OPERATING RANGES
Symbol
Parameter
Min
Typ
Max
Unit
V
CC
Supply Voltage
4.75
5.0
5.25
V
T
A
Operating Ambient
Temperature Range
0
25
70
C
I
OH
Output Current High
0.4
mA
I
OL
Output Current Low
8.0
mA
R
ext
External Timing Resistance
5.0
260
k
W
C
ext
External Capacitance
No Restriction
R
ext
/C
ext
Wiring Capacitance at
R
ext
/C
ext
Terminal
50
pF
LOW POWER SCHOTTKY
Device
Package
Shipping
ORDERING INFORMATION
SN74LS123N
16 Pin DIP
SN74LS123D
16 Pin
SOIC
D SUFFIX
CASE 751A
http://onsemi.com
PLASTIC
N SUFFIX
CASE 646
14
1
14
1
SOIC
D SUFFIX
CASE 751B
PLASTIC
N SUFFIX
CASE 648
16
1
16
1
SN74LS122N
14 Pin DIP
2000 Units/Box
SN74LS122D
14 Pin
2500/Tape & Reel
2000 Units/Box
2500/Tape & Reel
SN74LS122 SN74LS123
http://onsemi.com
2
SN74LS122 (TOP VIEW)
(SEE NOTES 1 THRU 4)
SN74LS123 (TOP VIEW)
(SEE NOTES 1 THRU 4)
NOTES:
1. An external timing capacitor may be connected between C
ext
and R
ext
/C
ext
(positive).
2. To use the internal timing resistor of the LS122, connect R
int
to V
CC
.
3. For improved pulse width accuracy connect an external resistor between R
ext
/C
ext
and V
CC
with R
int
open-circuited.
4. To obtain variable pulse widths, connect an external variable resistance between R
int
/C
ext
and V
CC
.
14
13
12
11
10
9
1
2
3
4
5
6
8
7
V
CC
R
ext/
C
ext
NC
C
ext
NC
R
int
Q
A1
A2
B1
B2
CLR
Q
GND
CLR Q
Q
R
int
2
R
ext/
C
ext
1
C
ext
1 R
ext/
C
ext
14
13
12
11
10
9
1
2
3
4
5
6
7
16
15
8
V
CC
1A
1Q
2Q
2B
2
CLR
2A
1B
1
CLR
1Q
2Q
2
C
ext
GND
Q
Q
Q
Q
CLR
CLR
NC -- NO INTERNAL CONNECTION.
SN74LS122 SN74LS123
http://onsemi.com
3
LS122 FUNCTIONAL TABLE
INPUTS
OUTPUTS
CLEAR
A1
A2
B1
B2
Q
Q
L
X
X
X
X
L
H
X
H
H
X
X
L
H
X
X
X
L
X
L
H
X
X
X
X
L
L
H
H
L
X
H
H
L
X
H
H
X
L
H
H
X
L
H
H
H
H
H
H
H
H
H
H
H
H
L
X
H
H
X
L
H
H
LS123 FUNCTIONAL TABLE
INPUTS
OUTPUTS
CLEAR
A
B
Q
Q
L
X
X
L
H
X
H
X
L
H
X
X
L
L
H
H
L
H
H
L
H
TYPICAL APPLICATION DATA
The output pulse t
W
is a function of the external
components, C
ext
and R
ext
or C
ext
and R
int
on the LS122.
For values of C
ext
1000 pF, the output pulse at V
CC
= 5.0
V and V
RC
= 5.0 V (see Figures 1, 2, and 3) is given by
t
W
= K R
ext
C
ext
where K is nominally 0.45
If C
ext
is on pF and R
ext
is in k
then t
W
is in nanoseconds.
The C
ext
terminal of the LS122 and LS123 is an internal
connection to ground, however for the best system
performance C
ext
should be hard-wired to ground.
Care should be taken to keep R
ext
and C
ext
as close to the
monostable as possible with a minimum amount of
inductance between the R
ext
/C
ext
junction and the R
ext
/C
ext
pin. Good groundplane and adequate bypassing should be
designed into the system for optimum performance to ensure
that no false triggering occurs.
It should be noted that the C
ext
pin is internally connected
to ground on the LS122 and LS123, but not on the LS221.
Therefore, if C
ext
is hard-wired externally to ground,
substitution of a LS221 onto a LS123 socket will cause the
LS221 to become non-functional.
The switching diode is not needed for electrolytic
capacitance application and should not be used on the LS122
and LS123.
To find the value of K for C
ext
1000 pF, refer to Figure 4.
Variations on V
CC
or V
RC
can cause the value of K to
change, 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 separate power supplies are used for V
CC
and V
RC
. If V
CC
is tied to V
RC
, Figure 7 shows how K will
vary with V
CC
and temperature. Remember, the changes in
R
ext
and C
ext
with temperature are not calculated and
included in the graph.
As long as C
ext
1000 pF and 5K
R
ext
260K, the
change in K with respect to R
ext
is negligible.
If C
ext
1000 pF the graph shown on Figure 8 can be used
to determine the output pulse width. Figure 9 shows how K
will change for C
ext
1000 pF if V
CC
and V
RC
are connected
to the same power supply. The pulse width t
W
in
nanoseconds is approximated by
t
W
= 6 + 0.05 C
ext
(pF) + 0.45 R
ext
(k
) C
ext
+ 11.6 R
ext
In order to trim the output pulse width, it is necessary to
include a variable resistor between V
CC
and the R
ext
/C
ext
pin
or between V
CC
and the R
ext
pin of the LS122. Figure 10, 11,
and 12 show how this can be done. R
ext
remote should be
kept as close to the monostable as possible.
Retriggering of the part, as shown in Figure 3, must not
occur before C
ext
is discharged or the retrigger pulse will not
have any effect. The discharge time of C
ext
in nanoseconds
is guaranteed to be less than 0.22 C
ext
(pF) and is typically
0.05 C
ext
(pF).
For the smallest possible deviation in output pulse widths
from various devices, it is suggested that C
ext
be kept
1000 pF.
SN74LS122 SN74LS123
http://onsemi.com
4
WAVEFORMS
EXTENDING PULSE WIDTH
OVERRIDING THE OUTPUT PULSE
B INPUT
Q OUTPUT
B INPUT
CLEAR INPUT
CLEAR PULSE
Q OUTPUT
OUTPUT WITHOUT CLEAR PULSE
RETRIGGER
PULSE
(See Application Data)
OUTPUT WITHOUT RETRIGGER
t
W
SN74LS122 SN74LS123
http://onsemi.com
5
DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE
(unless otherwise specified)
Limits
Symbol
Parameter
Min
Typ
Max
Unit
Test Conditions
V
IH
Input HIGH Voltage
2.0
V
Guaranteed Input HIGH Voltage for
All Inputs
V
IL
Input LOW Voltage
0.8
V
Guaranteed Input LOW Voltage for
All Inputs
V
IK
Input Clamp Diode Voltage
0.65
1.5
V
V
CC
= MIN, I
IN
= 18 mA
V
OH
Output HIGH Voltage
2.7
3.5
V
V
CC
= MIN, I
OH
= MAX, V
IN
= V
IH
or V
IL
per Truth Table
V
O
Output LOW Voltage
0.25
0.4
V
I
OL
= 4.0 mA
V
CC
= V
CC
MIN,
V
IN
= V
IL
or V
IH
V
OL
Output LOW Voltage
0.35
0.5
V
I
OL
= 8.0 mA
V
IN
= V
IL
or V
IH
per Truth Table
I
Input HIGH Current
20
A
V
CC
= MAX, V
IN
= 2.7 V
I
IH
Input HIGH Current
0.1
mA
V
CC
= MAX, V
IN
= 7.0 V
I
IL
Input LOW Current
0.4
mA
V
CC
= MAX, V
IN
= 0.4 V
I
OS
Short Circuit Current (Note 1)
20
100
mA
V
CC
= MAX
I
CC
Power Supply Current
LS122
11
mA
V
CC
= MAX
I
CC
Power Supply Current
LS123
20
mA
V
CC
= MAX
Note 1: Not more than one output should be shorted at a time, nor for more than 1 second.
AC CHARACTERISTICS
(T
A
= 25
C, V
CC
= 5.0 V)
Limits
Symbol
Parameter
Min
Typ
Max
Unit
Test Conditions
t
PLH
Propagation Delay, A to Q
23
33
ns
PLH
t
PHL
g
y
Propagation Delay, A to Q
32
45
ns
C
ext
= 0
t
PLH
Propagation Delay, B to Q
23
44
ns
ext
C
L
= 15 pF
PLH
t
PHL
g
y
Propagation Delay, B to Q
34
56
ns
R
ext
= 5.0 k
t
PLH
Propagation Delay, Clear to Q
28
45
ns
ext
R
L
= 2.0 k
PLH
t
PHL
g
y
Propagation Delay, Clear to Q
20
27
ns
t
W min
A or B to Q
116
200
ns
C
ext
= 1000 pF, R
ext
= 10 k
,
t
W
Q
A to B to Q
4.0
4.5
5.0
s
ext
ext
C
L
= 15 pF, R
L
= 2.0 k
AC SETUP REQUIREMENTS
(T
A
= 25
C, V
CC
= 5.0 V)
Limits
Symbol
Parameter
Min
Typ
Max
Unit
Test Conditions
t
W
Pulse Width
40
ns
SN74LS122 SN74LS123
http://onsemi.com
6
Figure 1.
Figure 2.
Figure 3.
Figure 4.
V
CC
V
RC
V
CC
C
ext
0.1
F
P
out
C
ext
R
ext
/
C
ext
V
CC
Q
CLR
B
CLR
B2
B1
A2
A1
1/2 LS123
LS122
R
ext
Q
GND
A
51
P
in
P
in
P
out
t
W
RETRIGGER
5K
R
ext
260K
10
1
0.1
0.01
0.001
0.3
0.35 0.4
0.45 0.5
0.55
K
EXTERNAL
CAP
ACIT
ANCE, C ( F)
ext
V
CC
V
RC
V
CC
C
ext
0.1
F
P
out
C
ext
R
ext
/
C
ext
V
CC
Q
R
ext
Q
GND
51
P
in
SN74LS122 SN74LS123
http://onsemi.com
7
Figure 5. K versus V
CC
Figure 6. K versus V
RC
Figure 7. K versus V
CC
and V
RC
V
CC
V
CC
= 5 V
C
ext
= 1000 pF
V
RC
C
ext
= 1000 pF
0.55
0.5
K
0.45
0.4
0.35
4.5
5
5.5
V
CC =
V
RC
125
C
70
C
25
C
0
C
55
C
V
RC
= 5 V
C
ext
= 1000 pF
125
C
70
C
0
C
55
C
125
C
25
C
0
C
55
C
70
C
25
C
100000
10000
1000
100
10
1
10
100
1000
t W
C
ext
, EXTERNAL TIMING CAPACITANCE (pF)
R
ext
= 80 k
R
ext
= 40 k
R
ext
= 20 k
R
ext
= 10 k
R
ext
= 5 k
, OUTPUT
PULSE WIDTH (ns)
R
ext
= 260 k
R
ext
= 160 k
4.5
5
5.5
4.5
5
5.5
0.55
0.5
K
0.45
0.4
0.35
0.55
0.5
K
0.45
0.4
0.35
Figure 8.
SN74LS122 SN74LS123
http://onsemi.com
8
Figure 9.
Figure 10. LS123 Remote Trimming Circuit
C
ext
= 200 pF
0.65
0.6
K
0.55
0.5
4.5
4.75
5
5.25
5.5
V
CC
VOLTS
125
C
70
C
25
C
0
C
55
C
V
CC
R
ext
REMOTE
R
ext
C
ext
PIN 7
OR 15
PIN 6
OR 14
SN74LS122 SN74LS123
http://onsemi.com
9
Figure 11. LS122 Remote Trimming Circuit Without R
ext
Figure 12. LS122 Remote Trimming Circuit with R
int
OPEN
V
CC
R
ext
REMOTE
R
ext
C
ext
PIN 13
PIN 11
PIN 9
V
CC
R
ext
REMOTE
PIN 13
PIN 11
PIN 9
SN74LS122 SN74LS123
http://onsemi.com
10
PACKAGE DIMENSIONS
1
7
14
8
B
A
DIM
MIN
MAX
MIN
MAX
MILLIMETERS
INCHES
A
0.715
0.770
18.16
18.80
B
0.240
0.260
6.10
6.60
C
0.145
0.185
3.69
4.69
D
0.015
0.021
0.38
0.53
F
0.040
0.070
1.02
1.78
G
0.100 BSC
2.54 BSC
H
0.052
0.095
1.32
2.41
J
0.008
0.015
0.20
0.38
K
0.115
0.135
2.92
3.43
L
M
10
10
N
0.015
0.039
0.38
1.01
_
_
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION L TO CENTER OF LEADS WHEN
FORMED PARALLEL.
4. DIMENSION B DOES NOT INCLUDE MOLD FLASH.
5. ROUNDED CORNERS OPTIONAL.
F
H
G
D
K
C
SEATING
PLANE
N
T
14 PL
M
0.13 (0.005)
L
M
J
0.290
0.310
7.37
7.87
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSIONS A AND B DO NOT INCLUDE
MOLD PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.15 (0.006)
PER SIDE.
5. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR
PROTRUSION SHALL BE 0.127 (0.005) TOTAL
IN EXCESS OF THE D DIMENSION AT
MAXIMUM MATERIAL CONDITION.
A
B
G
P
7 PL
14
8
7
1
M
0.25 (0.010)
B
M
S
B
M
0.25 (0.010)
A
S
T
T
F
R
X 45
SEATING
PLANE
D
14 PL
K
C
J
M
_
DIM
MIN
MAX
MIN
MAX
INCHES
MILLIMETERS
A
8.55
8.75
0.337
0.344
B
3.80
4.00
0.150
0.157
C
1.35
1.75
0.054
0.068
D
0.35
0.49
0.014
0.019
F
0.40
1.25
0.016
0.049
G
1.27 BSC
0.050 BSC
J
0.19
0.25
0.008
0.009
K
0.10
0.25
0.004
0.009
M
0
7
0
7
P
5.80
6.20
0.228
0.244
R
0.25
0.50
0.010
0.019
_
_
_
_
D SUFFIX
PLASTIC SOIC PACKAGE
CASE 751A03
ISSUE F
N SUFFIX
PLASTIC PACKAGE
CASE 64606
ISSUE M
SN74LS122 SN74LS123
http://onsemi.com
11
PACKAGE DIMENSIONS
N SUFFIX
PLASTIC PACKAGE
CASE 64808
ISSUE R
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION L TO CENTER OF LEADS WHEN
FORMED PARALLEL.
4. DIMENSION B DOES NOT INCLUDE MOLD FLASH.
5. ROUNDED CORNERS OPTIONAL.
A
B
F
C
S
H
G
D
J
L
M
16 PL
SEATING
1
8
9
16
K
PLANE
T
M
A
M
0.25 (0.010)
T
DIM
MIN
MAX
MIN
MAX
MILLIMETERS
INCHES
A
0.740
0.770
18.80
19.55
B
0.250
0.270
6.35
6.85
C
0.145
0.175
3.69
4.44
D
0.015
0.021
0.39
0.53
F
0.040
0.70
1.02
1.77
G
0.100 BSC
2.54 BSC
H
0.050 BSC
1.27 BSC
J
0.008
0.015
0.21
0.38
K
0.110
0.130
2.80
3.30
L
0.295
0.305
7.50
7.74
M
0
10
0
10
S
0.020
0.040
0.51
1.01
_
_
_
_
D SUFFIX
PLASTIC SOIC PACKAGE
CASE 751B05
ISSUE J
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSIONS A AND B DO NOT INCLUDE
MOLD PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.15 (0.006)
PER SIDE.
5. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR
PROTRUSION SHALL BE 0.127 (0.005) TOTAL
IN EXCESS OF THE D DIMENSION AT
MAXIMUM MATERIAL CONDITION.
1
8
16
9
SEATING
PLANE
F
J
M
R
X 45
_
G
8 PL
P
B
A
M
0.25 (0.010)
B
S
T
D
K
C
16 PL
S
B
M
0.25 (0.010)
A
S
T
DIM
MIN
MAX
MIN
MAX
INCHES
MILLIMETERS
A
9.80
10.00
0.386
0.393
B
3.80
4.00
0.150
0.157
C
1.35
1.75
0.054
0.068
D
0.35
0.49
0.014
0.019
F
0.40
1.25
0.016
0.049
G
1.27 BSC
0.050 BSC
J
0.19
0.25
0.008
0.009
K
0.10
0.25
0.004
0.009
M
0
7
0
7
P
5.80
6.20
0.229
0.244
R
0.25
0.50
0.010
0.019
_
_
_
_
SN74LS122 SN74LS123
http://onsemi.com
12
ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes
without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular
purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability,
including without limitation special, consequential or incidental damages. "Typical" parameters which may be provided in SCILLC data sheets and/or
specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be
validated for each customer application by customer's technical experts. SCILLC does not convey any license under its patent rights nor the rights of others.
SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications
intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or
death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold
SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable
attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim
alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer.
PUBLICATION ORDERING INFORMATION
ASIA/PACIFIC: LDC for ON Semiconductor Asia Support
Phone:
3036752121 (TueFri 9:00am to 1:00pm, Hong Kong Time)
Toll Free from Hong Kong 80044223781
Email: ONlitasia@hibbertco.com
JAPAN: ON Semiconductor, Japan Customer Focus Center
4321 NishiGotanda, Shinagawaku, Tokyo, Japan 1418549
Phone: 81354878345
Email: r14153@onsemi.com
Fax Response Line:
3036752167
8003443810 Toll Free USA/Canada
ON Semiconductor Website: http://onsemi.com
For additional information, please contact your local
Sales Representative.
SN74LS122/D
North America Literature Fulfillment:
Literature Distribution Center for ON Semiconductor
P.O. Box 5163, Denver, Colorado 80217 USA
Phone: 3036752175 or 8003443860 Toll Free USA/Canada
Fax: 3036752176 or 8003443867 Toll Free USA/Canada
Email: ONlit@hibbertco.com
N. American Technical Support: 8002829855 Toll Free USA/Canada
EUROPE: LDC for ON Semiconductor European Support
German Phone: (+1) 3033087140 (MF 2:30pm to 5:00pm Munich Time)
Email: ONlitgerman@hibbertco.com
French Phone: (+1) 3033087141 (MF 2:30pm to 5:00pm Toulouse Time)
Email: ONlitfrench@hibbertco.com
English Phone: (+1) 3033087142 (MF 1:30pm to 5:00pm UK Time)
Email: ONlit@hibbertco.com
PDF 
ZIP