6 Specifications

6.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted)(1)

MIN

MAX

UNIT

VCC

Supply voltage

–0.5

7

V

IIK

Input clamp current(2)

VI < 0 or VI > VCC

±20

mA

IOK

Output clamp current(2)

VO < 0 or VO > VCC

±20

mA

IO

Continuous output current

VO = 0 to VCC

±25

mA

Continuous current through VCC or GND

±50

mA

TJ

Junction temperature(3)

150

°C

Tstg

Storage temperature

–65

150

°C

(1)

Stresses beyond those listed under Absolute Maximum Rating may cause permanent damage to the device. These are stress

ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated

under Recommended Operating Condition. Exposure to absolute-maximum-rated conditions for extended periods may affect device

reliability.

(2)

The input and output voltage ratings may be exceeded if the input and output current ratings are observed.

(3)

Guaranteed by design.

6.2 Recommended Operating Conditions

over operating free-air temperature range (unless otherwise noted)

MIN

NOM

MAX

UNIT

VCC

Supply voltage

2

5

6

V

VIH

High-level input voltage

VCC = 2 V

1.5

V

VCC = 4.5 V

3.15

VCC = 6 V

4.2

VIL

Low-level input voltage

VCC = 2 V

0.5

V

VCC = 4.5 V

1.35

VCC = 6 V

1.8

VI

Input voltage

0

VCC

V

VO

Output voltage

0

VCC

V

tt

Input transition rise and fall time

VCC = 2 V

1000

ns

VCC = 4.5 V

500

VCC = 6 V

400

TA

Operating free-air temperature

SN54HC21

–55

125

°C

SN74HC21

–40

85

6.3 Thermal Information

THERMAL METRIC(1)

SN74HC21

UNIT

N (PDIP)

D (SOIC)

PW (TSSOP)

NS (SOP)

14 PINS

14 PINS

14 PINS

14 PINS

RθJA

Junction-to-ambient thermal

resistance

65.2

133.6

151.7

122.6

°C/W

RθJC(top)

Junction-to-case (top) thermal

resistance

44.9

89.0

79.4

81.8

°C/W

RθJB

Junction-to-board thermal

resistance

52.9

89.5

94.7

83.8

°C/W

ΨJT

Junction-to-top characterization

parameter

32.5

45.5

25.2

45.4

°C/W

ΨJB

Junction-to-board characterization

parameter

44.7

89.1

94.1

83.4

°C/W

SN74HC21, SN54HC21

SCLS087F – DECEMBER 1982 – REVISED JUNE 2021

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