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
;
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
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
; 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
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
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
-
-
s
5.0
C
EXT
= 100 nF;
R
EXT
= 10 k
;
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
;
note 1;
Figs 7 and 8
t
rt
retrigger time
nA, nB
110
-
-
ns
5.0
C
EXT
= 0 pF;
R
EXT
= 5 k
;
note 2; Fig. 7
R
EXT
external timing resistor
10
2
1000
1000
-
-
k
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
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
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
-
-
s
5.0
C
EXT
= 100 nF;
R
EXT
= 10 k
;
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
;
note 1; Figs 7 and
8
t
rt
retrigger time
nA, nB
110
-
-
ns
5.0
C
EXT
= 0 pF;
R
EXT
= 5 k
;
note 2; Fig.7
R
EXT
external timing resistor
2
1000
-
-
k
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
; 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
.
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
to 100 k
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
A
A
1
A
2
b
p
D
H
E
L
p
Q
detail X
E
Z
e
c
L
v
M
A
(A )
3
A
8
9
1
16
y
pin 1 index
UNIT
A
max.
A
1
A
2
A
3
b
p
c
D
(1)
E
(1)
(1)
e
H
E
L
L
p
Q
Z
y
w
v
REFERENCES
OUTLINE
VERSION
EUROPEAN
PROJECTION
ISSUE DATE
IEC
JEDEC
EIAJ
mm
inches
1.75
0.25
0.10
1.45
1.25
0.25
0.49
0.36
0.25
0.19
10.0
9.8
4.0
3.8
1.27
6.2
5.8
0.7
0.6
0.7
0.3
8
0
o
o
0.25
0.1
DIMENSIONS (inch dimensions are derived from the original mm dimensions)
Note
1. Plastic or metal protrusions of 0.15 mm maximum per side are not included.
1.0
0.4
SOT109-1
95-01-23
97-05-22
076E07S
MS-012AC
0.069
0.010
0.004
0.057
0.049
0.01
0.019
0.014
0.0100
0.0075
0.39
0.38
0.16
0.15
0.050
1.05
0.041
0.244
0.228
0.028
0.020
0.028
0.012
0.01
0.25
0.01
0.004
0.039
0.016
0
2.5
5 mm
scale
SO16: plastic small outline package; 16 leads; body width 3.9 mm
SOT109-1
1998 Jul 08
13
Philips Semiconductors
Product specification
Dual retriggerable monostable
multivibrator with reset
74HC/HCT423
SOLDERING
Introduction
There is no soldering method that is ideal for all IC
packages. Wave soldering is often preferred when
through-hole and surface mounted components are mixed
on one printed-circuit board. However, wave soldering is
not always suitable for surface mounted ICs, or for
printed-circuits with high population densities. In these
situations reflow soldering is often used.
This text gives a very brief insight to a complex technology.
A more in-depth account of soldering ICs can be found in
our
"Data Handbook IC26; Integrated Circuit Packages"
(order code 9398 652 90011).
DIP
S
OLDERING BY DIPPING OR BY WAVE
The maximum permissible temperature of the solder is
260
C; solder at this temperature must not be in contact
with the joint for more than 5 seconds. The total contact
time of successive solder waves must not exceed
5 seconds.
The device may be mounted up to the seating plane, but
the temperature of the plastic body must not exceed the
specified maximum storage temperature (T
stg max
). If the
printed-circuit board has been pre-heated, forced cooling
may be necessary immediately after soldering to keep the
temperature within the permissible limit.
R
EPAIRING SOLDERED JOINTS
Apply a low voltage soldering iron (less than 24 V) to the
lead(s) of the package, below the seating plane or not
more than 2 mm above it. If the temperature of the
soldering iron bit is less than 300
C it may remain in
contact for up to 10 seconds. If the bit temperature is
between 300 and 400
C, contact may be up to 5 seconds.
SO
R
EFLOW SOLDERING
Reflow soldering techniques are suitable for all SO
packages.
Reflow soldering requires solder paste (a suspension of
fine solder particles, flux and binding agent) to be applied
to the printed-circuit board by screen printing, stencilling or
pressure-syringe dispensing before package placement.
Several techniques exist for reflowing; for example,
thermal conduction by heated belt. Dwell times vary
between 50 and 300 seconds depending on heating
method. Typical reflow temperatures range from
215 to 250
C.
Preheating is necessary to dry the paste and evaporate
the binding agent. Preheating duration: 45 minutes at
45
C.
W
AVE SOLDERING
Wave soldering techniques can be used for all SO
packages if the following conditions are observed:
A double-wave (a turbulent wave with high upward
pressure followed by a smooth laminar wave) soldering
technique should be used.
The longitudinal axis of the package footprint must be
parallel to the solder flow.
The package footprint must incorporate solder thieves at
the downstream end.
During placement and before soldering, the package must
be fixed with a droplet of adhesive. The adhesive can be
applied by screen printing, pin transfer or syringe
dispensing. The package can be soldered after the
adhesive is cured.
Maximum permissible solder temperature is 260
C, and
maximum duration of package immersion in solder is
10 seconds, if cooled to less than 150
C within
6 seconds. Typical dwell time is 4 seconds at 250
C.
A mildly-activated flux will eliminate the need for removal
of corrosive residues in most applications.
R
EPAIRING SOLDERED JOINTS
Fix the component by first soldering two diagonally-
opposite end leads. Use only a low voltage soldering iron
(less than 24 V) applied to the flat part of the lead. Contact
time must be limited to 10 seconds at up to 300
C. When
using a dedicated tool, all other leads can be soldered in
one operation within 2 to 5 seconds between
270 and 320
C.
1998 Jul 08
14
Philips Semiconductors
Product specification
Dual retriggerable monostable
multivibrator with reset
74HC/HCT423
DEFINITIONS
LIFE SUPPORT APPLICATIONS
These products are not designed for use in life support appliances, devices, or systems where malfunction of these
products can reasonably be expected to result in personal injury. Philips customers using or selling these products for
use in such applications do so at their own risk and agree to fully indemnify Philips for any damages resulting from such
improper use or sale.
Data sheet status
Objective specification
This data sheet contains target or goal specifications for product development.
Preliminary specification
This data sheet contains preliminary data; supplementary data may be published later.
Product specification
This data sheet contains final product specifications.
Limiting values
Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one or
more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation
of the device at these or at any other conditions above those given in the Characteristics sections of the specification
is not implied. Exposure to limiting values for extended periods may affect device reliability.
Application information
Where application information is given, it is advisory and does not form part of the specification.
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