SN54/74LS122
SN54/74LS123
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.
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•
•
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RETRIGGERABLE MONOSTABLE
MULTIVIBRATORS
LOW POWER SCHOTTKY
Overriding Clear Terminates Output Pulse
Compensated for VCC 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
J SUFFIX
CERAMIC
CASE 620-09
16
1
SN54 / 74LS123 (TOP VIEW)
(SEE NOTES 1 THRU 4)
1 Rext/ 1
VCC Cext Cext
16
15
14
1Q
2Q
2
CLR
13
12
11
CLR Q
2
1B
3
1
CLR
2A
10
9
16
1
CLR
Q
Q
1
1A
2B
16
Q
4
1Q
5
2Q
1
6
2
Cext
8
7
2 GND
Rext/
Cext
Rext/
Cext
NC
13
12
Cext
11
NC
Rint
9
10
D SUFFIX
SOIC
CASE 751B-03
J SUFFIX
CERAMIC
CASE 632-08
14
SN54 / 74LS122 (TOP VIEW)
(SEE NOTES 1 THRU 4)
VCC
14
N SUFFIX
PLASTIC
CASE 648-08
1
Q
N SUFFIX
PLASTIC
CASE 646-06
8
Rint
Q
14
1
CLR Q
1
A1
2
A2
3
B1
4
B2
5
CLR
6
Q
7
GND
14
1
D SUFFIX
SOIC
CASE 751A-02
NC — NO INTERNAL CONNECTION.
NOTES:
1. An external timing capacitor may be connected between Cext and Rext/Cext (positive).
2. To use the internal timing resistor of the LS122, connect Rint to VCC.
3. For improved pulse width accuracy connect an external resistor between Rext/Cext and
VCC with Rint open-circuited.
4. To obtain variable pulse widths, connect an external variable resistance between Rint/Cext
and VCC.
FAST AND LS TTL DATA
5-1
ORDERING INFORMATION
SN54LSXXXJ
SN74LSXXXN
SN74LSXXXD
Ceramic
Plastic
SOIC