Datasheet 74HCT4538U, 74HCT4538N, 74HCT4538DB, 74HCT4538D, 74HC4538DB Datasheet (Philips)

DATA SH EET

Product specification
File under Integrated Circuits, IC06

September 1993

INTEGRATED CIRCUITS

74HC/HCT4538

Dual retriggerable precision
monostable multivibrator

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

September 1993 2

Philips Semiconductors Product specification

Dual retriggerable precision monostable
multivibrator

74HC/HCT4538

FEA TURES

• Separate reset inputs

• Triggering from leading or trailing edge

• Output capability: standard

• ICC category: MSI

• Power-on reset on-chip

GENERAL DESCRIPTION

The 74HC/HCT4538 are high-speed Si-gate CMOS
devices and are pin compatible with “4538” of the “4000B”
series. They are specified in compliance with JEDEC
standard no. 7A.

The 74HC/HCT4538 are dual retriggerable-resettable
monostable multivibrators. Each multivibrator has an
active LOW trigger/retrigger input (n

A0), an active HIGH

trigger/retrigger input (nA1) , an overriding active LOW
direct reset input (nRD), an output (nQ) and its complement
(nQ), and two pins (nCTCand nRCTC) for connecting the
external timing components Ctand Rt. Typical pulse width
variation over temperature range is ± 0.2%.

The “4538” may be triggered by either the positive or the
negative edges of the input pulse. The duration and
accuracy of the output pulse are determined by the
external timing components Ctand Rt. The output pulse
width (T) is equal to 0.7 × Rt× Ct. The linear design
techniques guarantee precise control of the output pulse
width.

A LOW level at nRDterminates the output pulse
immediately.

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

QUICK REFERENCE DATA

GND = 0 V; T

amb

= 25 °C; tr= tf= 6 ns

Notes

1. C

PD

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

PD= CPD× V

CC

2

× fi+∑(CL× V

CC

2

× fo) +

+ 0.48 × C

EXT

× V

CC

2

× fo+ D × 0.8 × VCCwhere:
fi= input frequency in MHz
fo= output frequency in MHz
∑ (CL× V

CC

2

× fo) = sum of outputs
CL= output load capacitance in pF
VCC= supply voltage in V
D = duty factor in %
C

EXT

= timing capacitance in pF

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

CC

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

ORDERING INFORMATION

See

“74HC/HCT/HCU/HCMOS Logic Package Information”

.

SYMBOL PARAMETER CONDITIONS

TYPICAL

UNIT

HC HCT

t

PHL

/ t

PLH

propagation delay nA0,nA1to nQ, nQC

L

= 15 pF; VCC= 5 V 27 30 ns

C

I

input capacitance 3.5 3.5 pF

C

PD

power dissipation capacitance per multivibrator notes 1 and 2 136 138 pF

September 1993 3

Philips Semiconductors Product specification

Dual retriggerable precision monostable
multivibrator

74HC/HCT4538

PIN DESCRIPTION

PIN NO. SYMBOL NAME AND FUNCTION

1, 15 1C

TC

,2C

TC

external capacitor connections

2, 14 1RC

TC

, 2RC

TC

external resistor/capacitor connections

3, 13 1

RD,2R

D

direct reset inputs (active LOW)

4, 12 1A

1

,2A

1

trigger inputs (LOW-to-HIGH, edge-triggered)

5, 11 1

A0,2A

0

trigger inputs (HIGH-to-LOW, edge-triggered)
6, 10 1Q, 2Q pulse outputs
7, 9 1

Q, 2Q complementary pulse outputs
8 GND ground (0 V)
16 V

CC

positive supply voltage

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

September 1993 4

Philips Semiconductors Product specification

Dual retriggerable precision monostable
multivibrator

74HC/HCT4538

Fig.4 Functional diagram.

Fig.5 Connection of the external timing

components Rtand Ct.

(1) Connect CTC(pins 1 and 15) to GND (pin 8).

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

INPUTS OUTPUTS

nA

0

nA

1

nR

D

nQ nQ

↓ LH

H↑H

XXL LH

Fig.6 Timing diagram.

(1) Positive edge triggering.
(2) Positive edge retriggering (pulse

lengthening).
(3) Negative edge triggering.
(4) Reset (pulse shortening).
(5) V

ref1

and V

ref2

are internal reference voltages.

(6) T = 0.7 × Rt× Ct(see also Fig.5).

September 1993 5

Philips Semiconductors Product specification

Dual retriggerable precision monostable
multivibrator

74HC/HCT4538

handbook, full pagewidth

MBA338

V

ref2

ref1

V

GND

nC

TC

nRC

TC

enable

enable

V

CC

power - on reset

V

CC

nR

D

nA

1

nA

0

nQ

nQ

Fig.7 Logic diagram (V

ref1

and V

ref2

are internal reference voltages).

September 1993 6

Philips Semiconductors Product specification

Dual retriggerable precision monostable
multivibrator

74HC/HCT4538

DC CHARACTERISTICS FOR 74HC

For the DC characteristics see

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

.

Output capability: standard
ICCcategory: MSI

AC CHARACTERISTICS FOR 74HC

GND = 0 V; t

r

= tf= 6 ns; CL= 50 pF

SYMBOL PARAMETER

T

amb

(°C)

UNIT

TEST CONDITIONS

74HC

V

CC

(V)

OTHER+25 −40 to +85 −40 to +125

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

t

PLH

propagation delay

nA0,nA1to nQ

85
31
25

265
53
45

330
66
56

400
80
68

ns 2.0

4.5

6.0

Fig.8

t

PHL

propagation delay

nA0,nA1to nQ

83
30
24

265
53
45

330
66
56

400
80
68

ns 2.0

4.5

6.0

Fig.8

t

PHL

propagation delay

nRDto nQ

80
29
23

265
53
45

330
66
56

400
80
68

ns 2.0

4.5

6.0

Fig.8

t

PLH

propagation delay

nRDto nQ

83
30
24

265
53
45

340
68
58

400
80
68

ns 2.0

4.5

6.0

Fig.8

t

THL

/ t

TLH

output transition
time

19
7
6

75
15
13

95
19
16

110
22
19

ns 2.0

4.5

6.0

Fig.8

t

W

nA0pulse width

LOW

80
16
14

17
6
5

100
20
17

120
24
20

ns 2.0

4.5

6.0

Fig.8

t

W

nA1pulse width

HIGH

80
16
14

17
6
5

100
20
17

120
24
20

ns 2.0

4.5

6.0

Fig.8

t

W

nRDpulse width

LOW

80
16
14

19
7
6

100
20
17

120
24
20

ns 2.0

4.5

6.0

Fig.8

t

W

nQ, nQ pulse width

HIGH or LOW

0.63 0.70 0.77 0.602 0.798 0.595 0.805 ms 5.0 Fig.8;
Rt= 10 kΩ;
Ct= 0.1 µF

t

rem

removal time

RDto nA0,nA

1

35
7
6

6
2
2

45
9
8

55
11
9

ns 2.0

4.5

6.0

Fig.8

September 1993 7

Philips Semiconductors Product specification

Dual retriggerable precision monostable
multivibrator

74HC/HCT4538

NON-STANDARD DC CHARACTERISTICS FOR 74HC

Voltages are referenced to GND (ground = 0 V)

Note

1. This measurement can only be carried out after a trigger pulse is applied.

t

rt

retrigger time

nA0,nA

1

−

−

−

455+X
80+X
55+X

−

−

−

−

−

−

ns 2.0

4.5

6.0

Fig.8
X=C

EXT

/

(4.5 × VCC)

R

EXT

external timing

resistor

10
2

1000
1000

kΩ 2.0

5.0

C

EXT

external timing

capacitor

no limits

pF 5.0

SYMBOL PARAMETER

T

amb

(°C)

UNIT

TEST CONDITIONS

74HC

V

CC

(V)

V

I

(V)

OTHER

+25 −40 to +85 −40 to +125

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

±I

I

input leakage current

nRC

EXT

0.5 5.0 10.0 µA 6.0 2.0
or
GND

VCCor GND;
note 1

SYMBOL PARAMETER

T

amb

(°C)

UNIT

TEST CONDITIONS

74HC

V

CC

(V)

OTHER+25 −40 to +85 −40 to +125

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

September 1993 8

Philips Semiconductors Product specification

Dual retriggerable precision monostable
multivibrator

74HC/HCT4538

DC CHARACTERISTICS FOR 74HCT

For the DC characteristics see

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

.

Output capability: standard
ICCcategory: MSI

Note to HCT types

The value of additional quiescent supply current (∆ICC) 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

= tf= 6 ns; CL= 50 pF

INPUT UNIT LOAD COEFFICIENT

n

A0,nA

1

nR

D

0.50

0.65

SYMBOL PARAMETER

T

amb

(°C)

UNIT

TEST CONDITIONS

74HCT

V

CC

(V)

OTHER

+25 −40 to +85 −40 to +125

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

t

PLH

propagation delay

nA0,nA1to nQ

35 60 75 90 ns 4.5 Fig.8

t

PHL

propagation delay

nA0,nA1to nQ

35 60 75 90 ns 4.5 Fig.8

t

PHL

propagation delay

nRDto nQ

35 60 75 90 ns 4.5 Fig.8

t

PLH

propagation delay

nRDto nQ

35 60 75 90 ns 4.5 Fig.8

t

THL

/ t

TLH

output transition time 7 15 19 21 ns 4.5 Fig.8

t

W

nA0pulse width

LOW

20 11 25 30 ns 4.5 Fig.8

t

W

nA1pulse width

HIGH

16 5 20 24 ns 4.5 Fig.8

t

W

nRDpulse width

LOW

20 11 25 30 ns 4.5 Fig.8

t

W

nQ, nQ pulse width

HIGH or LOW

0.63 0.70 0.77 0.602 0.798 0.595 0.805 ms 5.0 Fig.8; Rt= 10 kΩ;
Ct= 0.1 µF

t

rem

removal time

RDto nA0, nA1

7 2 9 11 ns 4.5 Fig.8

t

rt

retrigger time

nA0,nA

1

− 80+X −−ns 4.5 Fig.8

X=C

EXT

/

(4.5 × VCC)

R

EXT

external timing

resistor

2 1000 kΩ 5.0

C

EXT

external timing

capacitor

no limits

pF 5.0

September 1993 9

Philips Semiconductors Product specification

Dual retriggerable precision monostable
multivibrator

74HC/HCT4538

NON-STANDARD DC CHARACTERISTICS FOR 74HCT

Voltages are referenced to GND (ground = 0 V)

Note

1. This measurement can only be carried out after a trigger pulse is applied.

AC WAVEFORMS

SYMBOL PARAMETER

T

amb

(°C)

UNIT

TEST CONDITIONS

74HCT

V

CC

(V)

V

I

(V)

OTHER

+25 −40 to +85 −40 to +125

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

±I

I

input leakage current

nRC

EXT

0.5 5.0 10.0 µA 5.5 2.0
or
GND

VCCor GND;
note 1

Fig.8 Waveforms showing the input (nA1,nA0,nRD) to output (nQ, nQ) propagation delays, the output transition

times, the input and output pulse widths, the removal time from direct reset (nRD) to input (nA1,nA0), and
the input retrigger time.

(1) HC : VM= 50%; VI= GND to VCC.

HCT: V

M

= 1.3 V; VI= GND to 3 V.

September 1993 10

Philips Semiconductors Product specification

Dual retriggerable precision monostable
multivibrator

74HC/HCT4538

APPLICATION INFORMATION

Fig.9 Retriggerable monostable circuitry.

(a) rising-edge triggered; (b) falling-edge triggered.

(a) (b)

Fig.10 Non-retriggerable monostable circuitry.

(a) rising-edge triggered; (b) falling-edge triggered.

(a) (b)

September 1993 11

Philips Semiconductors Product specification

Dual retriggerable precision monostable
multivibrator

74HC/HCT4538

Fig.11 Power-down protection circuit.

Power-down considerations

A large capacitor (CX) 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 VCCto zero occurs,
the monostable may sustain damage, due to the capacitor
discharging through the input protection diodes. To avoid
this possibility, use a damping diode (DX) preferably a
germanium or Schottky type diode able to withstand large
current surges and connect as shown in Fig.11.

Fig.12 Typical pulse width accuracy versus external capacitance; VCC= 4.5 V; T

amb

= 25 °C.

Fig.13 Typical pulse width accuracy versus external resistance; VCC= 4.5 V; T

amb

= 25 °C.

September 1993 12

Philips Semiconductors Product specification

Dual retriggerable precision monostable
multivibrator

74HC/HCT4538

Fig.14 Typical pulse width accuracy versus external capacitance; R

EXT

= 10 kΩ;VCC= 4.5 V; T

amb

= 25 °C.

Fig.15 Typical pulse width accuracy versus power supply; C

EXT

= 1 nF; T

amb

= 25 °C.

Fig.16 Typical pulse width accuracy versus power supply; C

EXT

= 100 nF; T

amb

= 25 °C.

September 1993 13

Philips Semiconductors Product specification

Dual retriggerable precision monostable
multivibrator

74HC/HCT4538

PACKAGE OUTLINES

See

“74HC/HCT/HCU/HCMOS Logic Package Outlines”

.

Fig.17 Typical pulse width accuracy versus temperature; C

EXT

= 1 nF; VCC= 4.5 V.

Fig.18 Typical pulse width accuracy versus temperature; C

EXT

=1µF; VCC= 4.5 V.