Philips 74hc hct123 DATASHEETS

INTEGRATED CIRCUITS

DATA SH EET

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

74HC/HCT123

Dual retriggerable monostable
multivibrator with reset

Product specification
Supersedes data of September 1993
File under Integrated Circuits, IC06

1998 Jul 08

Philips Semiconductors Product specification

Dual retriggerable monostable
multivibrator with reset

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/CEXT

)

• ICC category: MSI

GENERAL DESCRIPTION

The 74HC/HCT123 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/HCT123 are dual
retriggerable monostable
multivibrators with output pulse width
control by three methods. The basic
pulse time is programmed by
selection of an external resistor

) and capacitor (C

(R

EXT

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.
Alternatively an output delay can be
terminated at any time by a
LOW-going edge on input nRD, which
also inhibits the triggering.

and early reset. The basic output
pulse width is essentially determined
by the values of the external timing
components R
pulse widths, when C
see Fig.9.

When C
output pulse width is defined as:

tW= 0.45 × R

QUICK REFERENCE DATA

GND = 0 V; T

SYMBOL PARAMETER CONDITIONS

t

PHL

C

I

C

PD

Notes

1. C

2. For HC the condition is VI= GND to V

74HC/HCT123

where:
t

= pulse width in ns;

W

R

= external resistor in kΩ;

EXT

and C

EXT

> 10 000 pF, the typical

EXT

× C

EXT

=25°C; tr=tf=6ns

amb

/ t

propagation delay CL=15pF;

PLH

n

A, nB to nQ, nQ2626ns

nRD to nQ, nQ

input capacitance 3.5 3.5 pF
power dissipation

capacitance per
monostable

is used to determine the dynamic power dissipation (PD in µW):

PD

PD=CPD× V

2

× V

× fo+ D × 16 × VCC where:

CC

CC

2

fi= input frequency in MHz
fo= output frequency in MHz
D = duty factor in %
CL= output load capacitance in pF
VCC= supply voltage in V
C

= timing capacitance in pF

EXT

∑ (CL× V

2

× fo) sum of outputs

CC

For HCT the condition is VI= GND to VCC− 1.5 V

. For

EXT

< 10 000 pF,

EXT

(typ.),

EXT

× fi+ ∑(CL× V

C

= external capacitor in pF.

EXT

Schmitt-trigger action in the nA and
nB inputs, makes the circuit highly
tolerant to slower input rise and fall
times.

The ‘123’ is identical to the ‘423’ but
can be triggered via the reset input.

TYPICAL

HC HCT

VCC=5V;
R

=5kΩ;

C

EXT
EXT

=0pF

20 23 ns

notes 1 and 2 54 56 pF

2

× fo) + 0.75 × C

CC

CC

EXT

UNIT

An internal connection from nRD to
the input gates makes it possible to
trigger the circuit by a positive-going
signal at input nRD as shown in the
function table. Figures 7 and 8
illustrate pulse control by retriggering

1998 Jul 08 2

Philips Semiconductors Product specification

Dual retriggerable monostable
multivibrator with reset

ORDERING INFORMATION

TYPE

NUMBER

74HC123N;
74HCT123N

74HC123D;
74HCT123D

74HC123DB;
74HCT123DB

74HC123PW;
74HCT123PW

PIN DESCRIPTION

PIN NO. SYMBOL NAME AND FUNCTION

1, 9 1
2, 10 1B, 2B trigger inputs (positive-edge triggered)
3, 11 1
4, 12 1
72R
8 GND ground (0 V)
13, 5 1Q, 2Q outputs (active HIGH)
14, 6 1C
15 1R
16 V

NAME DESCRIPTION VERSION

DIP16 plastic dual in-line package; 16leads (300 mil); long body SOT38-1

SO16 plastic small outline package; 16 leads; body width 3.9 mm SOT109-1

SSOP16 plastic shrink small outline package; 16 leads; body width 5.3 mm SOT338-1

TSSOP16 plastic thin shrink small outline package; 16 leads; body width 4.4 mm SOT403-1

A, 2A trigger inputs (negative-edge triggered)

RD, 2R

D

Q, 2Q outputs (active LOW)

EXT/CEXT

, 2C

EXT
EXT/CEXT

CC

EXT

PACKAGE

direct reset LOW and trigger action at positive edge

external resistor/capacitor connection

external capacitor connection
external resistor/capacitor connection
positive supply voltage

74HC/HCT123

Fig.1 Pin configuration. Fig.2 Logic symbol. Fig.3 IEC logic symbol.

1998 Jul 08 3

Philips Semiconductors Product specification

Dual retriggerable monostable
multivibrator with reset

FUNCTION TABLE

nRDnAnBnQ nQ

LXXL H
XHX L
XXL L
HL ↑

H↓ H
↑LH

Note

1. If the monostable was triggered
before this condition was

Fig.4 Functional diagram.

established, the pulse will
continue as programmed.

INPUTS OUTPUTS

(1)
(1)

(1)

H

(1)

H

74HC/HCT123

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

(1) For minimum noise generation,

it is recommended to ground pins 6 (2C
and 14 (1C

) externally to pin 8 (GND).

EXT

EXT

)

Fig.5 Logic diagram.

1998 Jul 08 4

Philips Semiconductors Product specification

Dual retriggerable monostable
multivibrator with reset

Fig.6 Timing component connections.

DC CHARACTERISTICS FOR 74HC

For the DC characteristics see
Output capability: standard (except for nR

ICC category: MSI

“74HC/HCT/HCU/HCMOS Logic Family Specifications”

EXT/CEXT

74HC/HCT123

.

)

1998 Jul 08 5

Philips Semiconductors Product specification

Dual retriggerable monostable
multivibrator with reset

AC CHARACTERISTICS FOR 74HC

GND = 0 V; t

SYMBOL PARAMETER

t

PLH

t

PLH

t

PHL

t

PLH

/ t

t

THL

TLH

t

W

t

W

t

W

t

W

t

W

t

rt

R

EXT

C

EXT

= 6 ns; CL=50pF

r=tf

propagation delay

nRD, nA, nB to nQ

propagation delay

nRD, nA, nB to nQ

propagation delay

nRD to nQ (reset)

propagation delay

nRD to nQ (reset)

output transition
time

trigger pulse width

nA = LOW

trigger pulse width

nB = HIGH

reset pulse width

nRD= LOW

output pulse width

nQ = HIGH
nQ = LOW

output pulse width

nQ = HIGH
nQ = LOW

retrigger time

nA, nB

external timing
resistor

external timing
capacitor

min. typ. max. min. max. min. max.

83
30
24

83
30
24

66
24
19

66
24
19

19
7
6

100

8

20

3

17

2

100

17

20

6

17

5

100

14

20

5

17

4

450 −−µs 5.0

75 −−ns 5.0

110 −−ns 5.0

10
2

T

(°C)

amb

74HC

+25 −40 to +85 −40 to +125

255
51
43

255
51
43

215
43
37

215
43
37

75
15
13

1000
1000

320
64

385
7765ns

54
320

64

385
7765ns

54
270

54

325
6555ns

46
270

54

325
6555ns

46
95

19

110
2219ns

16

125
25
21

125
25
21

125
25
21

150
30
26

150
30
26

150
30
26

−−kΩ

no limits pF 5.0 Fig.9; note 3

UNIT

ns

ns

ns

74HC/HCT123

TEST CONDITIONS

V

(V)

2.0

4.5

6.0

2.0

4.5

6.0

2.0

4.5

6.0

2.0

4.5

6.0

2.0

4.5

6.0

2.0

4.5

6.0

2.0

4.5

6.0

2.0

4.5

6.0

2.0

5.0

CC

WAVEFORMS/

NOTES

C

= 0 pF;

EXT

R

=5kΩ

EXT

C

= 0 pF;

EXT

R

=5kΩ

EXT

C

= 0 pF;

EXT

R

=5kΩ

EXT

C

= 0 pF;

EXT

R

=5kΩ

EXT

Fig.7

Fig.7

Fig.8

C

= 100 nF;

EXT

R

=10kΩ;

EXT

Figs 7 and 8
C

= 0 pF;

EXT

R

=5kΩ;

EXT

note 1; Figs 7 and 8
C

= 0 pF;

EXT

R

=5kΩ;

EXT

note 2; Fig.7
Fig.9

1998 Jul 08 6