Philips 74AHCT123A, 74AHC123A Datasheet

INTEGRATED CIRCUITS

DATA SH EET

74AHC123A; 74AHCT123A

Dual retriggerable monostable
multivibrator with reset

Product specification
File under Integrated Circuits, IC06

2000 Mar 15

Philips Semiconductors Product specification

Dual retriggerable monostable multivibrator
with reset

FEATURES

• ESD protection:
HBM EIA/JESD22-A114-A exceeds 2000 V
MM EIA/JESD22-A115-A exceeds 200 V
CDM EIA/JESD22-C101 exceeds 1000 V

• All inputs have Schmitt-trigger actions

• Inputs accept voltages higher than V

CC

• For AHC only: operates with CMOS input levels

• For AHCT only: operates with TTL input levels

• Specified from −40 to +85 °C and −40 to +125 °C

• DC triggered from active HIGH or active LOW inputs

• Retriggerable for very long pulses up to 100% duty

factor

• Direct reset terminates output pulse

• Output capability: standard (except for nR

EXT/CEXT

).

DESCRIPTION

The 74AHC/AHCT123A 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.

Once triggered, the basic output pulse width may be
extendedbyretriggeringthegatedactiveLOW-goingedge
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.
Alternativelyan output delay can beterminatedat any time
by a LOW-going edgeon input nRD, which also inhibitsthe
triggering.

An internal connection from nRDto the input gate makes it
possible to trigger the circuit by a positive-going signal at
input nRD as shown in the function table. Figs 8 and 9
illustrate pulse control by retriggering and early reset. The
basic output pulse width is essentially determined by the
value of the external timing components R
When C
definedas: tW=R
R

EXT

in pF. Schmitt-trigger action at all 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.

74AHC123A;

74AHCT123A

≥ 10 nF, the typical output pulse width is

EXT

× C

EXT

= external resistor in kΩ; C

wheretW= pulsewidth in ns;

EXT

= external capacitor

EXT

EXT

and C

EXT

.

The74AHC/AHCT123Aaredualretriggerablemonostable
multivibrators with output pulse width control by three
methods. The basic pulse time is programmed by
selection of an external resistor (R
(C

). The external resistor and capacitor are normally

EXT

) and capacitor

EXT

connected as shown in Fig.6.

2000 Mar 15 2

Philips Semiconductors Product specification

Dual retriggerable monostable multivibrator
with reset

QUICK REFERENCE DATA

GND = 0 V; T

SYMBOL PARAMETER CONDITIONS

t

PHL/tPLH

C

I

C

O

C

PD

Notes

1. C

is used to determine the dynamic power dissipation (PDin µW).

PD

PD=CPD× V
fi= input frequency in MHz;
fo= output frequency in MHz;
∑ (CL× V
D = duty factor in %;
CL= output load capacitance in pF;
C

= timing capacitance in pF;

EXT

VCC= supply voltage in Volts.

2. The condition is VI= GND to VCC.

=25°C; tr=tf≤3.0 ns.

amb

propagation delay CL= 15 pF; VCC=5V;

R

=5kΩ; C

n

A, nB to nQ, nQ 5.1 5.0 ns

n

RDto nQ, nQ 5.6 5.2 ns

EXT

input capacitance VI=VCCor GND 5 3 pF
output capacitance 4 4 pF
power dissipation capacitance CL= 50 pF; f = 1 MHz; notes 1

and 2

2

× fi+ ∑ (CL× V

CC

2

× fo) = sum of outputs;

CC

CC

2

× fo) × C

EXT

× V

2

× fo+D×16 × VCCwhere:

CC

EXT

74AHC123A;

74AHCT123A

TYPICAL

UNIT

AHC AHCT

=0pF

57 58 pF

2000 Mar 15 3

Philips Semiconductors Product specification

Dual retriggerable monostable multivibrator
with reset

74AHC123A;

74AHCT123A

FUNCTION TABLE

See note 1.

INPUTS OUTPUTS

R

n

D

nAnB nQ nQ

LXX L H
XHX L
XXL L
HL↑
H ↓ H
↑ LH

(2)
(2)

(3) (4)
(3) (4)
(3) (4)

(2)

H

(2)

H

Notes

1 H = HIGH voltage level;

L = LOW voltage level;
X = don’t care;

↑ = LOW-to-HIGH CP transition;
↓ = HIGH-to-LOW CP transition.

2 If the monostable multivibrator was triggered before this condition was established, the pulse will be continued as

programmed.
3 One HIGH-level output pulse.
4 One LOW-level output pulse.

ORDERING INFORMATION

PACKAGES

TYPE NUMBER

TEMPERATURE

RANGE

PINS PACKAGE MATERIAL CODE

74AHC123AD −40 to +125 °C 16 SO plastic SOT109-1
74AHC123APW 16 TSSOP plastic SOT403-1
74AHCT123AD 16 SO plastic SOT109-1
74AHCT123APW 16 TSSOP plastic SOT403-1

2000 Mar 15 4

Philips Semiconductors Product specification

Dual retriggerable monostable multivibrator
with reset

PINNING

PIN SYMBOL DESCRIPTION

1, 9 1
2, 10 1B, 2B trigger inputs (positive-edge triggered)
3, 11 1
4, 12 1
5, 13 2Q, 1Q outputs (active HIGH)
6, 14 2C
7, 15 2R
8 GND ground (0 V)
16 V

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

RD,2R

D

direct reset LOW and trigger action at positive edge

Q, 2Q outputs (active LOW)

, 1C

EXT
EXT/CEXT

CC

EXT

, 1R

EXT/CEXT

external capacitor connection
external resistor/capacitor connection

DC supply voltage

74AHC123A;

74AHCT123A

handbook, halfpage

2R

EXT/CEXT

1A

1
2

1B

1R

3

D

1Q

4

123

5

2Q

6

2C

EXT

7

GND

8

MNA514

Fig.1 Pin configuration.

16
15
14
13
12
11
10

9

V

CC

1R

EXT/CEXT

1C

EXT

1Q

2Q
2R

D

2B
2A

handbook, halfpage

11A
9

2

10 2B

3

11

2A

1B

1R

D

2R

D

Fig.2 Logic diagram.

1C

14

EXT

2C

1R

EXT/CEXT

2R

EXT/CEXT

S

Q

T

R

D

EXT

1Q
2Q 5

1QQ4
2Q 12

MNA515

6

15

7

13

2000 Mar 15 5

Philips Semiconductors Product specification

Dual retriggerable monostable multivibrator
with reset

handbook, halfpage

14
15

1
2

3

6
7

9
10

11

CX
RCX

&

R

CX
RCX

&

R

13

4

5

12

MNA516

handbook, halfpage

11A
9

2

10 2B

3

11

2A

1B

1R
2R

74AHC123A;

74AHCT123A

1C

14

EXT

2C

1R

EXT/CEXT

2R

EXT/CEXT

S

Q

T

R

D

D
D

EXT

1Q
2Q 5

1QQ4
2Q 12

MNA517

6

15

7

13

Fig.3 IEC logic symbol.

Fig.4 Functional diagram.

2000 Mar 15 6

Philips Semiconductors Product specification

Dual retriggerable monostable multivibrator
with reset

handbook, full pagewidth

R

D

CL

R

CL

V

CC

R

R

V

CC

nR

EXT/CEXT

V

CC

74AHC123A;

74AHCT123A

Q

Q

CL

MNA518

A

B

For minimum noise generation, it is recommended to ground pins 6 (2CEXT) and 14 (1CEXT) externally to pin 8 (GND).

R

CL CL

Fig.5 Logic diagram (one flip-flop).

2000 Mar 15 7

Philips Semiconductors Product specification

Dual retriggerable monostable multivibrator
with reset

handbook, halfpage

C

to nC

EXT

(pin 14 or 6)

EXT

V

to nR

EXT/CEXT

(pin 15 or 7)

CC

MNA519

R

EXT

74AHC123A;

74AHCT123A

Fig.6 Timing component connections.

RECOMMENDED OPERATING CONDITIONS

SYMBOL PARAMETER CONDITIONS

V

CC

V

I

V

O

T

amb

t

, t

r

f

R

EXT

C

EXT

DC supply voltage 2.0 5.0 5.5 4.5 5.0 5.5 V
input voltage 0 − 5.5 0 − 5.5 V
output voltage 0 − V
operating ambient

temperature
input rise and fall

time ratios
external timing

resistor

see DC and AC
characteristics per device

VCC= 3.3 ±0.3 V −−100 −−−ns/V
V

=5±0.5 V −−20 −−20 ns/V

CC

VCC=2V 5 −−5−−kΩ
V

>3V 1 −−1−−kΩ

CC

external timing
capacitor

74AHC 74AHCT

UNIT

MIN. TYP. MAX. MIN. TYP. MAX.

0 − V

CC

CC

V

−40 +25 +85 −40 +25 +85 °C

−40 +25 +125 −40 +25 +125 °C

no limits pF

2000 Mar 15 8