HD74LS123 Datasheet, PDF (4/9 Pages) Hitachi Semiconductor – Dual Retriggerable Monostable Multivibrators(with Clear)

HD74LS123
Switching Characteristics
(V_CC = 5 V, Ta = 25°C)
Item
Symbol Inputs Outputs min. typ. max. Unit
Condition
t_PLH
A
t_PHL
Q
—
23
33
Q
—
32
45
Propagation delay
t_PLH
B
time
t_PHL
Q
Q
—
—
23
34
44
56
ns
C_ext = 0, R_ext = 5 kΩ,
C_L = 15 pF, R_L = 2 kΩ
t_PLH
CLR
t_PHL
Q
—
20
27
Q
—
28
45
Output pulse width
t_(out)min
t_(out)
A, B
Q
—
116 200
C_ext = 1000 pF,
Q
4
4.5
5
µs R_ext = 10 kΩ,
C_L = 15 pF, R_L = 2 kΩ
Typical Application Data for HD74LS123
For pulse widths when C_ext ≤ 1000 pF, See Figure 3.
The output pulse is primarily a function of the external capacitor and resistor. For C_ext > 1000 pF, the output pulse
width (t_w) is defined as: t_w(out) = K • R_ext • C_ext; See Figure 4.
V_CC
Rext
+
Cext
–
to Cext to Rext/Cext
Rext (kΩ)
Cext (pF)
t_w(out) (ns)
Figure 2
Timing Component Connections
100,000
10,000
Rext = 160kΩ
Figure 3
1,000
100
10
1
Rext = 80kΩ
40kΩ
20kΩ
10kΩ
5kΩ
10
100
1,000
External capacitance Cext (pF)
Typical Output Pulse Width (Cext ≤ 1000 pF)
Rev.2.00, Feb.18.2005, page 4 of 8