Document
HD74LS123
Dual Retriggerable Monostable Multivibrators (with Clear)
REJ03D0429–0200 Rev.2.00
Feb.18.2005
This d-c triggered multivibrator features output pulse width control by three method. The basic pulse time is programmed by selection of external resistance and capacitance values. 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. Figure 1 illustrates pulse control by retriggering and early clear. This device is provided enough Schmitt hysteresis to ensure jitter-free triggering from the B input with transition rates as slow as 0.1 mV/ns.
Features
• Ordering Information
Part Name
Package Type
Package Code (Previous Code)
Package Abbreviation
HD74LS123P
DILP-16 pin
PRDP0016AE-B
P
(DP-16FV)
HD74LS123FPEL SOP-16 pin (JEITA)
PRSP0016DH-B (FP-16DAV)
FP
PRSP0016DG-A
HD74LS123RPEL SOP-16 pin (JEDEC) (FP-16DNV)
RP
Note: Please consult the sales office for the above package availability.
Taping Abbreviation (Quantity) —
EL (2,000 pcs/reel)
EL (2,500 pcs/reel)
A = "L" Clear = "H" B
Q
A = "L" B
Clear Q
Retrigger Pulse "H"
"L"
tw + tPLH "H"
tw
"L"
Output without retrigger
"H"
"L" "H"
"L"
Output without clear
"H" "L"
Figure 1
Typical Input / Output Pulse
Rev.2.00, Feb.18.2005, page 1 of 8
HD74LS123
Pin Arrangement
1A 1 1B 2 1CLR 3 1Q 4 2Q 5 2Cext 6 2Rext/Cext 7 GND 8
CLR QQ
QQ CLR
16 VCC 15 1Rext/Cext 14 1Cext 13 1Q 12 2Q 11 2CLR 10 2B 9 2A
(Top view)
Function Table
Inputs
Clear
A1
L
X
X
H
X
X
H
L
H
↓
↑
L
Notes: H; high level, L; low level, X; irrelevant
↑; transition from low to high level
↓; transition from high to low level
; one high-level pulse
; one low-level pulse
Block Diagram (1/2)
B2 X X L ↑ H H
External parameter
Outputs
Q
Q
L
H
L
H
L
H
A B
Clear
Cext Rext VCC /Cext QQ
QQ Clear
Rev.2.00, Feb.18.2005, page 2 of 8
HD74LS123
Absolute Maximum Ratings
Item
Symbol
Ratings
Unit
Supply voltage
VCC
7
V
Input voltage
VIN
7
V
Power dissipation Storage temperature
PT Tstg
400
mW
–65 to +150
°C
Note: Voltage value, unless otherwise noted, are with respect to network ground terminal.
Recommended Operating Conditions
Supply voltage
Item
Output current
Operating temperature
Input pulse width
“H” A, B
“L”
CLR “L”
External timing resistance
External capacitance
Wiring capacitance at Rext/Cext terminal
Symbol VCC IOH IOL Topr
tw (in)
Rext Cext
Min 4.75 — — –20 40 40 40
5
—
Typ
Max
Unit
5.00
5.25
V
—
–400
µA
—
8
mA
25
75
°C
—
—
ns
—
—
ns
—
—
ns
—
260
kΩ
Non restriction
—
50
pF
Electrical Characteristics
(Ta = –20 to +75 °C)
Item
Symbol
min.
typ.* max.
Unit
Condition
Input voltage
Output voltage
Input current Short-circuit output current
VIH
2.0
—
—
V
VIL
—
—
0.8
V
VOH
2.7
—
—
V
VCC = 4.75 V, VIH = 2 V, VIL = 0.8 V, IOH = –400 µA
VOL
— —
—
0.4
—
0.5
V
IOL = 4 mA IOL = 8.