DATA SHEET
Product specification
Supersedes data of December 1990
File under Integrated Circuits, IC06
1998 Jul 08
INTEGRATED CIRCUITS
74HC/HCT423
Dual retriggerable monostable
multivibrator with reset
For a complete data sheet, please also download:
•
The IC06 74HC/HCT/HCU/HCMOS Logic Family Specifications
•
The IC06 74HC/HCT/HCU/HCMOS Logic Package Information
•
The IC06 74HC/HCT/HCU/HCMOS Logic Package Outlines
1998 Jul 08
2
Philips Semiconductors
Product specification
Dual retriggerable monostable
multivibrator with reset
74HC/HCT423
FEATURES
•
DC triggered from active HIGH or active LOW inputs
•
Retriggerable for very long pulses up to 100% duty
factor
•
Direct reset terminates output pulse
•
Schmitt-trigger action on all inputs except for the reset
input
•
Output capability: standard (except for nR
EXT
/C
EXT
)
•
I
CC
category: MSI
GENERAL DESCRIPTION
The 74HC/HCT423 are high-speed Si-gate CMOS devices
and are pin compatible with low power Schottky TTL
(LSTTL). They are specified in compliance with JEDEC
standard no. 7A.
The 74HC/HCT423 are dual retriggerable monostable
multivibrators with output pulse width control by two
methods. The basic pulse time is programmed by
selection of an external resistor (R
EXT
) and capacitor
(C
EXT
). The external resistor and capacitor are normally
connected as shown in Fig.6.
Once triggered, the basic output pulse width may be
extended by retriggering the gated active LOW-going edge
input (nA) or the active HIGH-going edge input (nB). By
repeating this process, the output pulse period
(nQ = HIGH, nQ = LOW) can be made as long as desired.
When nR
D
is LOW, it forces the nQ output LOW, the
nQ output HIGH and also inhibits the triggering.
Figures 7 and 8 illustrate pulse control by reset. The basic
output pulse width is essentially determined by the values
of the external timing components R
EXT
and C
EXT
.
For pulse widths, when C
EXT
<
10 000 pF, see Fig.9.
When C
EXT
>
10 000 pF, the typical output pulse width is
defined as:
t
W
= 0.45
×
R
EXT
×
C
EXT
(typ.),
where, t
W
= pulse width in ns;
R
EXT
= external resistor in k
Ω
;
C
EXT
= external capacitor in pF.
Schmitt-trigger action in the nA and nB inputs, makes the
circuit highly tolerant to slower input rise and fall times.
The “423” is identical to the “123” but cannot be triggered
via the reset input.
QUICK REFERENCE DATA
GND = 0 V; T
amb
= 25
°
C; t
r
= t
f
= 6 ns
Notes
1. C
PD
is used to determine the dynamic power dissipation (P
D
in
µ
W):
P
D
= C
PD
×
V
CC
2
×
f
i
+ ∑
(C
L
×
V
CC
2
×
f
o
)
+
0.75
×
C
EXT
×
V
CC
2
×
f
o
+
D
×
16
×
V
CC
where:
f
i
= input frequency in MHz
f
o
= output frequency in MHz
D = duty factor in %
∑
(C
L
×
V
CC
2
×
f
o
) = sum of outputs
C
L
= output load capacitance in pF
V
CC
= supply voltage in V
C
EXT
= timing capacitance in pF
2. For HC the condition is V
I
= GND to V
CC
For HCT the condition is V
I
= GND to V
CC
−
1.5 V
SYMBOL
PARAMETER
CONDITIONS
TYPICAL
UNIT
HC
HCT
t
PHL
/ t
PLH
propagation delay
C
L
= 15 pF; V
CC
= 5 V;
R
EXT
= 5 k
Ω
; C
EXT
= 0 pF
nA, nB to nQ, nQ
25
26
ns
nR
D
to nQ, nQ
20
22
ns
C
I
input capacitance
3.5
3.5
pF
t
W
minimum output pulse width nQ, nQ
notes 1 and 2
75
75
ns
1998 Jul 08
3
Philips Semiconductors
Product specification
Dual retriggerable monostable
multivibrator with reset
74HC/HCT423
ORDERING INFORMATION
PIN DESCRIPTION
TYPE
NUMBER
PACKAGE
NAME
DESCRIPTION
VERSION
74HC423N;
74HCT423N
DIP16
plastic dual in-line package; 16 leads (300 mil); long body
SOT38-1
74HC423D;
74HCT423D
SO16
plastic small outline package; 16 leads; body width 3.9 mm;
low stand-off height
SOT109-1
PIN NO.
SYMBOL
NAME AND FUNCTION
1, 9
1A, 2A
trigger inputs (negative-edge triggered)
2, 10
1B, 2B
trigger inputs (positive-edge triggered)
3, 11
1R
D
, 2R
D
direct reset action (active LOW)
4, 12
1Q, 2Q
outputs (active LOW)
7
2R
EXT
/C
EXT
external resistor/capacitor connection
8
GND
ground (0 V)
13, 5
1Q, 2Q
outputs (active HIGH)
14, 6
1C
EXT
, 2C
EXT
external capacitor connection
15
1R
EXT
/C
EXT
external resistor/capacitor connection
16
V
CC
positive supply voltage
Fig.1 Pin configuration.
Fig.2
Fig.3 IEC logic symbol.
1998 Jul 08
4
Philips Semiconductors
Product specification
Dual retriggerable monostable
multivibrator with reset
74HC/HCT423
FUNCTION TABLE
Notes
1. H = HIGH voltage level
L = LOW voltage level
X = don’t care
↑
= LOW-to-HIGH transition
↓
= HIGH-to-LOW transition
= one HIGH level output pulse
= one LOW level output pulse
2. If the monostable was triggered before this condition was established, the pulse will continue as programmed.
INPUTS
OUTPUTS
nR
D
nA
nB
nQ
nQ
L
X
X
L
H
X
H
X
L
(2)
H
(2)
X
X
L
L
(2)
H
(2)
H
L
↑
H
↓
H
Fig.4 Functional diagram.
1998 Jul 08
5
Philips Semiconductors
Product specification
Dual retriggerable monostable
multivibrator with reset
74HC/HCT423
Fig.5 Logic diagram.
It is recommended to ground pins 6 (2C
EXT
) and 14
(1C
EXT
) externally to pin 8 (GND).
Fig.6 Timing component connections.
1998 Jul 08
6
Philips Semiconductors
Product specification
Dual retriggerable monostable
multivibrator with reset
74HC/HCT423
DC CHARACTERISTICS FOR 74HC
For the DC characteristics see
“74HC/HCT/HCU/HCMOS Logic Family Specifications”
.
Output capability: standard (except for nR
EXT
/C
EXT
)
I
CC
category: MSI
AC CHARACTERISTICS FOR 74HC
GND = 0 V; t
r
= t
f
= 6 ns; C
L
= 50 pF
SYMBOL
PARAMETER
T
amb
(
°
C)
UNIT
TEST CONDITIONS
74HC
V
CC
(V)
WAVEFORMS/
NOTES
+
25
−
40 to
+
85
−
40 to
+
125
min. typ. max
min max min.
max.
t
PHL
/ t
PLH
propagation delay
nA, nB to nQ, nQ
80
255
320
385
ns
2.0
C
EXT
= 0 pF;
R
EXT
= 5 k
Ω
29
51
64
77
4.5
23
43
54
65
6.0
t
PHL
/ t
PLH
propagation delay
nR
D
to nQ, nQ
66
215
270
325
ns
2.0
C
EXT
= 0 pF;
R
EXT
= 5 k
Ω
24
43
54
65
4.5
19
37
46
55
6.0
t
THL
/ t
TLH
output transition time
19
75
95
110
ns
2.0
7
15
19
22
4.5
6
13
16
19
6.0
t
W
trigger pulse width
nA = LOW
100
11
125
150
ns
2.0
Fig.7
20
4
25
30
4.5
17
3
21
26
6.0
t
W
trigger pulse width
nB = HIGH
100
17
125
150
ns
2.0
Fig.7
20
6
25
30
4.5
17
5
21
26
6.0
t
W
reset pulse width
nR
D
= LOW
100
14
125
150
ns
2.0
Fig.8
20
5
25
30
4.5
17
4
21
26
6.0
t
W
output pulse width
nQ = HIGH
nQ = LOW
450
−
−
µ
s
5.0
C
EXT
= 100 nF;
R
EXT
= 10 k
Ω
;
Figs 7 and 8
t
W
output pulse width
nQ = HIGH
nQ = LOW
75
−
−
ns
5.0
C
EXT
= 0 pF;
R
EXT
= 5 k
Ω
;
note 1;
Figs 7 and 8
t
rt
retrigger time
nA, nB
110
−
−
ns
5.0
C
EXT
= 0 pF;
R
EXT
= 5 k
Ω
;
note 2; Fig. 7
R
EXT
external timing resistor
10
2
1000
1000
−
−
k
Ω
2.0
5.0
Fig.9
C
EXT
external timing capacitor
no limits
pF
5.0
Fig.9; note 3
1998 Jul 08
7
Philips Semiconductors
Product specification
Dual retriggerable monostable
multivibrator with reset
74HC/HCT423
DC CHARACTERISTICS FOR 74HCT
For the DC characteristics see
“74HC/HCT/HCU/HCMOS Logic Family Specifications”
.
Output capability: standard (except for nR
EXT
/C
EXT
)
I
CC
category: MSI
Note to HCT types
The value of additional quiescent supply current (
∆
I
CC
) for a unit load of 1 is given in the family specifications.
To determine
∆
I
CC
per input, multiply this value by the unit load coefficient shown in the table below.
AC CHARACTERISTICS FOR 74HCT
GND = 0 V; t
r
= t
f
= 6 ns; C
L
= 50 pF
INPUT
UNIT LOAD COEFFICIENT
nA, nB
0.35
nR
D
0.50
SYMBOL PARAMETER
T
amb
(
°
C)
UNIT
TEST CONDITIONS
74HCT
V
CC
(V)
WAVEFORMS/
NOTES
+
25
−
40 to
+
85
−
40 to
+
125
min. typ. max. min. max. min.
max.
t
PHL
/ t
PLH
propagation delay
nA, nB to nQ, nQ
30
51
64
77
ns
4.5
C
EXT
= 0 pF;
R
EXT
= 5 k
Ω
t
PHL
/ t
PLH
propagation delay
nR
D
to nQ, nQ
26
48
60
72
ns
4.5
C
EXT
= 0 pF;
R
EXT
= 5 k
Ω
t
THL
/ t
TLH
output transition time
7
15
19
22
ns
4.5
t
W
trigger pulse width
nA = LOW
20
5
25
30
ns
4.5
Fig.7
t
W
trigger pulse width
nB = HIGH
20
5
25
30
ns
4.5
Fig.7
t
W
reset pulse width
nR
D
= LOW
20
7
25
30
ns
4.5
Fig.8
t
W
output pulse width
nQ = HIGH
nQ = LOW
450
−
−
µ
s
5.0
C
EXT
= 100 nF;
R
EXT
= 10 k
Ω
;
Figs 7 and 8
t
W
output pulse width
nQ = HIGH
nQ = LOW
75
−
−
ns
5.0
C
EXT
= 0 pF;
R
EXT
= 5 k
Ω
;
note 1; Figs 7 and
8
t
rt
retrigger time
nA, nB
110
−
−
ns
5.0
C
EXT
= 0 pF;
R
EXT
= 5 k
Ω
;
note 2; Fig.7
R
EXT
external timing resistor
2
1000
−
−
k
Ω
5.0
Fig.9
C
EXT
external timing
capacitor
no limits
pF
5.0
Fig.9; note 3
1998 Jul 08
8
Philips Semiconductors
Product specification
Dual retriggerable monostable
multivibrator with reset
74HC/HCT423
Notes
1. For other R
EXT
and C
EXT
combinations see Fig.9.
If C
EXT
>
10 pF, the next formula is valid:
t
W
= K
×
R
EXT
×
C
EXT
(typ.)
where: t
W
= output pulse width in ns;
R
EXT
= external resistor in k
Ω
; C
EXT
= external capacitor in pF;
K
= constant = 0.45 for V
CC
= 5.0 V and 0.55 for V
CC
= 2.0 V.
The inherent test jig and pin capacitance at pins 15 and 7 (nR
EXT
/C
EXT
) is approximately 7 pF.
2. The time to retrigger the monostable multivibrator depends on the values of R
EXT
and C
EXT
.
The output pulse width will only be extended when the time between the active-going edges of the trigger input pulses
meets the minimum retrigger time.
If C
EXT
>
10 pF, the next formula (at V
CC
= 5.0 V) for the set-up time of a retrigger pulse is valid:
t
rt
= 30
+
0.19
×
R
EXT
×
C
EXT
0.9
+
13
×
R
EXT
1.05
(typ.)
where, t
rt
= retrigger time in ns;
C
EXT
= external capacitor in pF;
R
EXT
= external resistor in k
Ω
.
The inherent test jig and pin capacitance at pins 15 and 7 (nR
EXT
/C
EXT
) is 7 pF.
3. When the device is powered-up, initiate the device via a reset pulse, when C
EXT
<
50 pF.
AC WAVEFORMS
Fig.7 Output pulse control using retrigger pulse; nR
D
= HIGH.
Fig.8 Output pulse control using reset input nR
D
; nA = LOW.
1998 Jul 08
9
Philips Semiconductors
Product specification
Dual retriggerable monostable
multivibrator with reset
74HC/HCT423
Fig.9
Typical output pulse width as a function of the external capacitor values at V
CC
= 5.0 V and T
amb
= 25
°
C.
Fig.10 Typical ‘K’ factor; external capacitance = 10 nF, external resistance = 10 k
Ω
to 100 k
Ω
and T
amb
= 25
°
C.
1998 Jul 08
10
Philips Semiconductors
Product specification
Dual retriggerable monostable
multivibrator with reset
74HC/HCT423
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
X
and
C
X
, this output pulse can be eliminated using the circuit shown in Fig.11.
Power-down considerations
A large capacitor (C
X
) may cause problems when powering-down 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
CC
to zero occurs, the
monostable may substain damage, due to the capacitor discharging through the input protection diodes. To avoid this
possibility, use a damping diode (D
X
) preferably a germanium or Schottky-type diode able to withstand large current
surges and connect as shown in Fig.12.
Fig.11 Power-up output pulse elimination circuit.
Fig.12 Power-down protection circuit.
1998 Jul 08
11
Philips Semiconductors
Product specification
Dual retriggerable monostable
multivibrator with reset
74HC/HCT423
PACKAGE OUTLINES
UNIT
A
max.
1
2
b
1
c
E
e
M
H
L
REFERENCES
OUTLINE
VERSION
EUROPEAN
PROJECTION
ISSUE DATE
IEC
JEDEC
EIAJ
mm
inches
DIMENSIONS (inch dimensions are derived from the original mm dimensions)
SOT38-1
92-10-02
95-01-19
A
min.
A
max.
b
max.
w
M
E
e
1
1.40
1.14
0.055
0.045
0.53
0.38
0.32
0.23
21.8
21.4
0.86
0.84
6.48
6.20
0.26
0.24
3.9
3.4
0.15
0.13
0.254
2.54
7.62
0.30
8.25
7.80
0.32
0.31
9.5
8.3
0.37
0.33
2.2
0.087
4.7
0.51
3.7
0.15
0.021
0.015
0.013
0.009
0.01
0.10
0.020
0.19
050G09
MO-001AE
M
H
c
(e )
1
M
E
A
L
seating plane
A
1
w
M
b
1
e
D
A
2
Z
16
1
9
8
b
E
pin 1 index
0
5
10 mm
scale
Note
1. Plastic or metal protrusions of 0.25 mm maximum per side are not included.
(1)
(1)
D
(1)
Z
DIP16: plastic dual in-line package; 16 leads (300 mil); long body
SOT38-1
1998 Jul 08
12
Philips Semiconductors
Product specification
Dual retriggerable monostable
multivibrator with reset
74HC/HCT423
X
w
M
θ
A
A
1
A
2
b
p
D
H