Datasheet SN74LS123M, SN74LS123MEL, SN74LS123ML1, SN74LS123ML2, SN74LS123MR1 Datasheet (MOTOROLA)

 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

T emperature 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/Cext

Wiring Capacitance at

R

ext/Cext

Terminal

50 pF

LOW POWER SCHOTTKY

Device Package Shipping

ORDERING INFORMATION

SN74LS123N 16 Pin DIP
SN74LS123D 16 Pin

SOIC

D SUFFIX

CASE 751A

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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

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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/Cext

(positive).

2. T o use the internal timing resistor of the LS122, connect R

int

to VCC.

3. For improved pulse width accuracy connect an external resistor between R

ext/Cext

and VCC with R

int

open-circuited.

4. To obtain variable pulse widths, connect an external variable resistance between R

int/Cext

and VCC.

14 13 12 11 10 9

123456

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

1R

ext/

C

ext

14 13 12 11 10 9

123456

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.

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LS122 FUNCTIONAL TABLE

INPUTS OUTPUTS

CLEAR A1 A2 B1 B2 Q Q

L X X X X L H
X H HXXLH
X X XLXLH
X X XXLLH
H L X ↑ H
H L XH↑
H X L ↑ H
H X LH↑
H H ↓ HH
H ↓ ↓ HH
H ↓ HHH

↑ L XHH
↑ X L H H

LS123 FUNCTIONAL TABLE

INPUTS OUTPUTS

CLEAR A B Q Q

L X X L H
X H XLH

X X LLH
H L ↑
H ↓ H

↑ L H

TYPICAL APPLICATION DATA

The output pulse tW 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 VCC = 5.0

V and VRC = 5.0 V (see Figures 1, 2, and 3) is given by

tW = K R

ext Cext

where K is nominally 0.45

If C

ext

is on pF and R

ext

is in kΩ then tW 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/Cext

junction and the R

ext/Cext

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 VCC or VRC 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 VRC. If VCC is tied to VRC, Figure 7 shows how K will
vary with VCC 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 VCC and VRC are connected

to the same power supply. The pulse width tW in
nanoseconds is approximated by

tW = 6 + 0.05 C

ext

(pF) + 0.45 R

ext

(kΩ) C

ext

+ 11.6 R

ext

In order to trim the output pulse width, it is necessary to

include a variable resistor between VCC and the R

ext/Cext

pin

or between VCC 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.

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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

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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 VCC = MIN, IIN = –18 mA

V

OH

Output HIGH Voltage

2.7 3.5 V VCC = MIN, IOH = MAX, VIN = V

IH

or VIL per Truth Table

p

0.25 0.4 V IOL = 4.0 mA

VCC = VCC MIN,

VOLOutput LOW Voltage

0.35 0.5 V IOL = 8.0 mA

V

IN

=

V

IL

or

V

IH

per Truth Table

p

20 µA VCC = MAX, VIN = 2.7 V

IIHInput HIGH Current

0.1 mA VCC = MAX, VIN = 7.0 V

I

IL

Input LOW Current –0.4 mA VCC = MAX, VIN = 0.4 V

I

OS

Short Circuit Current (Note 1) –20 –100 mA VCC = MAX

pp

LS122 11

ICCPower 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, VCC = 5.0 V)

Limits

Symbol Parameter

Min Typ Max

Unit Test Conditions

t

PLH

Propagation Delay, A to Q

23 33

PLH

t

PHL

gy

Propagation Delay, A to Q

32 45

ns

C

e

xt

= 0

t

PLH

Propagation Delay, B to Q

23 44

ext

CL = 15 pF

PLH

t

PHL

gy

Propagation Delay, B to Q

34 56

ns

R

ext

= 5.0 kΩ

t

PLH

Propagation Delay, Clear to Q

28 45

ext

RL = 2.0 kΩ

PLH

t

PHL

gy

Propagation Delay, Clear to Q

20 27

ns

t

Wmin

A or B to Q 116 200 ns

C

ext

= 1000 pF, R

ext

= 10 kΩ,

tWQ A to B to Q 4.0 4.5 5.0 µs

ext ext

CL = 15 pF, RL = 2.0 kΩ

AC SETUP REQUIREMENTS (T

A

= 25°C, VCC = 5.0 V)

Limits

Symbol Parameter

Min Typ Max

Unit Test Conditions

t

W

Pulse Width 40 ns

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6

Figure 1. Figure 2.

Figure 3.

Figure 4.

V

CC

V

RC

V

CC

C

ext

0.1 µF

P

out

C

extRext

/

C

ext

V

CC

Q

CLR
B

CLR
B2
B1
A2
A1

1/2 LS123

LS122

R

ext

Q

GND

A

51 Ω

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 CAPACITANCE, C ( F)

µ

ext

V

CC

V

RC

V

CC

C

ext

0.1 µF

P

out

C

ext

R

ext

/

C

ext

V

CC

Q

R

ext

Q

GND

51 Ω

P

in

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7

Figure 5. K versus V

CC

Figure 6. K versus V

RC

Figure 7. K versus VCC and V

RC

V

CC

VCC = 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

VRC = 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 kΩ

R

ext

= 40 kΩ

R

ext

= 20 kΩ

R

ext

= 10 kΩ

R

ext

= 5 kΩ

, OUTPUT PULSE WIDTH (ns)

R

ext

= 260 kΩ

R

ext

= 160 kΩ

4.5 5 5.54.5 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

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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

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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

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10

P ACKAGE DIMENSIONS

17

14 8

B

A

DIM MIN MAX MIN MAX

MILLIMETERSINCHES

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

HG

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

71

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

INCHESMILLIMETERS

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 751A–03

ISSUE F

N SUFFIX

PLASTIC PACKAGE

CASE 646–06

ISSUE M

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P ACKAGE DIMENSIONS

N SUFFIX

PLASTIC PACKAGE

CASE 648–08

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

18

916

K

PLANE

–T–

M

A

M

0.25 (0.010) T

DIM MIN MAX MIN MAX

MILLIMETERSINCHES

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 751B–05

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.

18

16 9

SEATING

PLANE

F

J

M

R

X 45

_

G

8 PLP

–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

INCHESMILLIMETERS

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

____

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