74LV123 Philips, 74LV123 Datasheet - Page 10

• Manufacturer Part Number: 74LV123
• Description: Dual retriggerable monostable multivibrator with reset
• Manufacturer: Philips

Philips Semiconductors
1998 Apr 28
Dual retriggerable monostable multivibrator
with reset
t
ns
W
external capacitor values at V
Figure 5.Typical output pulse width as a function of the
Figure 4. HCT typical “k” factor as a function of V
10
10
10
10
10
‘K’ factor
0
6
5
4
3
2
1
0.8
0.4
0
0
C
X
= 10 nF; R
1
10
2
X
V
= 10 KW to 100 KW.
CC
C
3
EXT
(V)
10
CC
2
(pF)
50kW
= 3.3V and T
R
100kW
4
EXT
=
5
SV00185
10
3
amb
2kW
6
= 25 C.
10kW
CC
SV00141
;
10
4
10
APPLICATION INFORMATION
Power-up considerations
When the monostable is powered-up it may produce an output
pulse, with a pulse width defined by the values of R
output pulse can be eliminated using the circuit shown in Figure 6.
Power-down considerations
A large capacitor (C
the monostable due to the energy stored in this capacitor. When a
system containing this device is powered-down or a rapid decrease
of V
the capacitor discharging through the input protection diodes. To
avoid this possibility, connect a damping diode (D
germanium or Schottky type diode able to withstand large current
surges as shown in Figure 7.
CC
Figure 6. Power-up output pulse elimination circuit
to zero occurs, the monostable may sustain damage, due to
A
B
Figure 7. Power-down protection circuit
C
nR
X
EXT
X
) may cause problems when powering-down
/C
EXT
nC
EXT
RESET
D
R
X
“123”
X
C
X
nR
R
EXT
X
Product specification
SV00152
/C
SV00154
X
EXT
74LV123
) preferably a
V
X
V
CC
Q
Q
CC
and C
V
CC
X
. This