ST M74HC148 User Manual

M74HC148

8 TO 3 LI NE PRIO RITY ENCODER

■ HIGH SPEED:

t

= 16ns (TYP.) at VCC = 6V

PD

■ LOW POWER DISSIPATION:

I

= 4µA(MAX.) at TA=25°C

CC

■ HIGH NOISE IMMUNITY:

V

= V

NIH

■ SYMMETRICAL OUTPUT IMPEDANCE:

|I

| = IOL = 4mA (MIN)

OH

■ BALANCED PROPAGATION DELAYS:

t

≅ t

PLH

■ WIDE OPERATING VOLTAGE RANGE:

V

(OPR) = 2V to 6V

CC

■ PIN AND FUNCTION COMPATIBLE WITH

= 28 % VCC (MIN.)

NIL

PHL

74 SERIES 148

DESCRIPTION

The M74HC148 is an hi gh speed CMOS 8 TO 3
LINE PRIORITY ENCODER fabricated with
silicon gate C

2

MOS technology.
The M74HC148 encodes eight data lines to
three-line (4-2-1) binary (octal). Cascading
circuitry (enable input EI and enab le output EO)

TSSOPDIP SOP

ORDER CODES

PACKAGE TUBE T & R

DIP M74HC148B1R

SOP M74HC148M1R M74HC148RM13TR

TSSOP M74HC148TTR

has been provided to allow octal expansion
without the need for external circuitry. Data inputs
are active at the low logic level.
All inputs are equipped with protection circuits
against static discharge and transient excess
voltage.

PIN CONNECTION AND IEC LOGIC SYMBOLS

1/11July 2001

M74HC148

INPUT AND OUTPUT EQUIVALENT CIRCUIT PIN DESCRIPTION

PIN No SYMBOL NAME AND FUNCTION

9, 7, 6 A

10, 11, 12,

13, 1, 2, 3, 4

15 EO Enable Output

5 EI Enable Input

14 GS Priority Flag Output

8 GND Ground (0V)

16 V

TRUTH TABLE

INPUTS OUTPUTS

E101234567A2A1A0GSE0

HXXXXXXXXHHHHH

LHHHHHHHHHHHHL
LXXXXXXXLLLLLH
LXXXXXXLHLLHLH
LXXXXXLHHLHLLH
LXXXXLHHHLHHLH
LXXXLHHHHHL LLH
LXXLHHHHHHLHLH
LXLHHHHHHHHL LH
LLHHHHHHHHHHLH

X : Don’t Care

to A2Data Outputs

0

0 to 7 Data Inputs

CC

Positive Supply Voltage

LOGIC DIAGRAM

This log i c diagram has not be used to est i m at e propagation delays

2/11

M74HC148

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

V

V

I

I

OK

I

I

or I

CC

P

T

T

Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is
not implied
(*) 500mW at 65

RECOMMENDED OPERATING CONDITIONS

Symbol Parameter Value Unit

V

V

V

T

t

r

Supply Voltage

CC

DC Input Voltage -0.5 to VCC + 0.5

I

DC Output Voltage -0.5 to VCC + 0.5

O

DC Input Diode Current

IK

DC Output Diode Current
DC Output Current

O

DC VCC or Ground Current

GND

Power Dissipation

D

Storage Temperature

stg

Lead Temperature (10 sec)

L

°C; derate to 300mW by 10mW/°C from 65°C to 85°C

Supply Voltage

CC

Input Voltage 0 to V

I

Output Voltage 0 to V

O

Operating Temperature

op

Input Rise and Fall Time VCC = 2.0V

, t

f

V
V

CC
CC

= 4.5V
= 6.0V

-0.5 to +7 V

± 20 mA
± 20 mA
± 25 mA
± 50 mA

500(*) mW

-65 to +150 °C

300 °C

2 to 6 V

CC
CC

-55 to 125 °C
0 to 1000 ns

0 to 500 ns
0 to 400 ns

V
V

V
V

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M74HC148

DC SPECIFICATIONS

Symbol Parameter

V

V

V

V

I

High Level Input

IH

Voltage

Low Level Input

IL

Voltage

High Level Output

OH

Voltage

Low Level Output

OL

Voltage

I

Input Leakage

I

Current
Quiescent Supply

CC

Current

Test Condition Value

V

(V)

CC

= 25°C

A

Min. Typ. Max. Min. Max. Min. Max.

-40 to 85°C -55 to 125°C

T

2.0 1.5 1.5 1.5

6.0 4.2 4.2 4.2

2.0 0.5 0.5 0.5

6.0 1.8 1.8 1.8

2.0

4.5

6.0

4.5

6.0

2.0

4.5

6.0

4.5

6.0

6.0

6.0

IO=-20 µA
I

=-20 µA

O

I

=-20 µA

O

I

=-4.0 mA

O

I

=-5.2 mA

O

IO=20 µA
I

=20 µA

O

I

=20 µA

O

I

=4.0 mA

O

I

=5.2 mA

O

= VCC or GND

V

I

= VCC or GND

V

I

1.9 2.0 1.9 1.9

4.4 4.5 4.4 4.4

5.9 6.0 5.9 5.9

4.18 4.31 4.13 4.10

5.68 5.8 5.63 5.60

0.0 0.1 0.1 0.1

0.0 0.1 0.1 0.1

0.0 0.1 0.1 0.1

0.17 0.26 0.33 0.40

0.18 0.26 0.33 0.40
± 0.1 ± 1 ± 1 µA

44080µA

Unit

V4.5 3.15 3.15 3.15

V4.5 1.35 1.35 1.35

V

V

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