54LS123 View Datasheet(PDF) - Motorola => Freescale
Part Name
Description
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54LS123 Datasheet PDF : 10 Pages
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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.
• 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
SN54 / 74LS123 (TOP VIEW)
(SEE NOTES 1 THRU 4)
VCC
1ĂRext/
Cext
1
Cext
16
15
14
1Q
13
2Q
12
2
CLR
11
2B
10
2A
9
Q
CLR Q
CLR
Q
Q
1
1A
2
1B
3
1
CLR
4
1Q
5
2Q
6
2
Cext
7
8
2
GND
Rext/
Cext
SN54 / 74LS122 (TOP VIEW)
(SEE NOTES 1 THRU 4)
Rext/
VCC
Cext
NC
Cext
NC
Rint
Q
14
13
12
11
10
9
8
Rint
Q
Q
CLR
1
A1
2
A2
3
B1
NC Ċ NO INTERNAL CONNECTION.
4
B2
5
CLR
6
7
Q
GND
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.
SN54/74LS122
SN54/74LS123
RETRIGGERABLE MONOSTABLE
MULTIVIBRATORS
LOW POWER SCHOTTKY
16
1
16
1
16
1
14
1
J SUFFIX
CERAMIC
CASE 620-09
N SUFFIX
PLASTIC
CASE 648-08
D SUFFIX
SOIC
CASE 751B-03
J SUFFIX
CERAMIC
CASE 632-08
14
1
14
1
N SUFFIX
PLASTIC
CASE 646-06
D SUFFIX
SOIC
CASE 751A-02
ORDERING INFORMATION
SN54LSXXXJ Ceramic
SN74LSXXXN Plastic
SN74LSXXXD SOIC
FAST AND LS TTL DATA
5-197
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