74HCT221
Dual non-retriggerable monostable multivibrator with reset
Rev. 3 — 26 October 2016
Product data sheet
1. General description
The 74HCT221 is a dual non-retriggerable monostable multivibrator. Each multivibrator
features edge-triggered inputs (nA and nB), either of which can be used as an enable
input. Pulse triggering occurs at a particular voltage level and is not directly related to the
transition time of the input pulse. Schmitt-trigger input circuitry for the nB inputs allow
jitter-free triggering from inputs with slow transition rates, providing the circuit with
excellent noise immunity. Once triggered, the outputs (nQ, nQ) are independent of further
transitions of nA and nB inputs. The output pulse width is defined by the following
relationship: t
W
= 0.7
C
EXT
R
EXT
The output pulses can be terminated by the active
LOW reset inputs (nRD). Pulse width stability is achieved through internal compensation
and is virtually independent of V
CC
and temperature. In most applications pulse stability
will only be limited by the accuracy of the external timing components. Inputs include
clamp diodes. This enables the use of current limiting resistors to interface inputs to
voltages in excess of V
CC
.
2. Features and benefits
Input levels:
For 74HCT221: TTL level
Pulse width variance is typically less than
5%
Direct reset terminates output pulse
Schmitt-trigger action on nB inputs
ESD protection:
HBM JESD22-A114F exceeds 2000 V
MM JESD22-A115-A exceeds 200 V
Specified from
40 C
to +85
C
and from
40 C
to +125
C
3. Ordering information
Table 1.
Ordering information
Temperature range
74HCT221D
40 C
to +125
C
Name
SO16
Description
plastic small outline package; 16 leads; body width 3.9 mm
Version
SOT109-1
Type number Package
Nexperia
74HCT221
Dual non-retriggerable monostable multivibrator with reset
4. Functional diagram
Fig 1.
Functional diagram
Fig 2.
Logic symbol
Fig 3.
IEC logic symbol
74HCT221
All information provided in this document is subject to legal disclaimers.
©
Nexperia B.V. 2017. All rights reserved
Product data sheet
Rev. 3 — 26 October 2016
2 of 19
Nexperia
74HCT221
Dual non-retriggerable monostable multivibrator with reset
Fig 4.
Logic diagram
It is recommended to connect pins nCEXT externally to the GND pin.
Fig 5.
Timing component connections
74HCT221
All information provided in this document is subject to legal disclaimers.
©
Nexperia B.V. 2017. All rights reserved
Product data sheet
Rev. 3 — 26 October 2016
3 of 19
Nexperia
74HCT221
Dual non-retriggerable monostable multivibrator with reset
5. Pinning information
5.1 Pinning
Fig 6.
Pin configuration for SO16
5.2 Pin description
Table 2.
Symbol
1A
1B
1RD
1Q
2Q
2CEXT
2REXT/CEXT
GND
2A
2B
2RD
2Q
1Q
1CEXT
1REXT/CEXT
V
CC
Pin description
Pin
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Description
negative-edge triggered input 1
positive-edge triggered input 1
direct reset LOW and positive-edge triggered input 1
active LOW output 1
active HIGH output 2
external capacitor connection 2
external resistor and capacitor connection 2
ground (0 V)
negative-edge triggered input 2
positive-edge triggered input 2
direct reset LOW and positive-edge triggered input 2
active LOW output 2
active HIGH output 1
external capacitor connection 1
external resistor and capacitor connection 1
supply voltage
74HCT221
All information provided in this document is subject to legal disclaimers.
©
Nexperia B.V. 2017. All rights reserved
Product data sheet
Rev. 3 — 26 October 2016
4 of 19
Nexperia
74HCT221
Dual non-retriggerable monostable multivibrator with reset
6. Functional description
Table 3.
Input
nRD
L
X
X
H
H
[1]
Function table
[1]
Output
nA
X
H
X
L
L
nB
X
X
L
H
H
[3]
[3]
nQ
L
L
[2]
L
[2]
nQ
H
H
[2]
H
[2]
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]
[3]
If the monostable was triggered before this condition was established, the pulse will continue as programmed.
For this combination the reset input must be LOW and the following sequence must be used:
pin nA must be set HIGH or pin nB set LOW; then pin nA must be LOW and pin nB set HIGH. Now the reset input goes from
LOW-to-HIGH and the device will be triggered.
7. Limiting values
Table 4.
Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134). Voltages are referenced to GND (ground = 0 V).
Symbol
V
CC
I
IK
I
OK
I
O
I
CC
I
GND
T
stg
P
tot
[1]
Parameter
supply voltage
input clamping current
output clamping current
output current
supply current
ground current
storage temperature
total power dissipation
Conditions
V
I
<
0.5
V or V
I
> V
CC
+ 0.5 V
V
O
<
0.5
V or V
O
> V
CC
+ 0.5 V
except for pins nREXT/CEXT;
V
O
=
0.5
V to (V
CC
+ 0.5 V)
Min
0.5
-
-
-
-
50
65
Max
+7
20
20
25
50
-
+150
500
Unit
V
mA
mA
mA
mA
mA
C
mW
SO16 package
[1]
-
For SO16 package: P
tot
derates linearly with 8 mW/K above 70
C.
74HCT221
All information provided in this document is subject to legal disclaimers.
©
Nexperia B.V. 2017. All rights reserved
Product data sheet
Rev. 3 — 26 October 2016
5 of 19
Microchip MCU
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