1/11
July 2001
s
HIGH SPEED:
t
PD
= 16ns (TYP.) at V
CC
= 6V
s
LOW POWER DISSIPATION:
I
CC
= 4
A(MAX.) at T
A
=25C
s
HIGH NOISE IMMUNITY:
V
NIH
= V
NIL
= 28 % V
CC
(MIN.)
s
SYMMETRICAL OUTPUT IMPEDANCE:
|I
OH
| = I
OL
= 4mA (MIN)
s
BALANCED PROPAGATION DELAYS:
t
PLH
t
PHL
s
WIDE OPERATING VOLTAGE RANGE:
V
CC
(OPR) = 2V to 6V
s
PIN AND FUNCTION COMPATIBLE WITH
74 SERIES 148
DESCRIPTION
The M74HC148 is an high 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 enable output EO)
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.
M74HC148
8 TO 3 LINE PRIORITY ENCODER
PIN CONNECTION AND IEC LOGIC SYMBOLS
ORDER CODES
PACKAGE
TUBE
T & R
DIP
M74HC148B1R
SOP
M74HC148M1R
M74HC148RM13TR
TSSOP
M74HC148TTR
TSSOP
DIP
SOP
M74HC148
2/11
INPUT AND OUTPUT EQUIVALENT CIRCUIT
PIN DESCRIPTION
TRUTH TABLE
X : Don't Care
LOGIC DIAGRAM
This logic diagram has not be used to estimate propagation delays
PIN No
SYMBOL
NAME AND FUNCTION
9, 7, 6
A
0
to A
2
Data Outputs
10, 11, 12,
13, 1, 2, 3, 4
0 to 7
Data Inputs
15
EO
Enable Output
5
EI
Enable Input
14
GS
Priority Flag Output
8
GND
Ground (0V)
16
V
CC
Positive Supply Voltage
INPUTS
OUTPUTS
E1
0
1
2
3
4
5
6
7
A2
A1
A0
GS
E0
H
X
X
X
X
X
X
X
X
H
H
H
H
H
L
H
H
H
H
H
H
H
H
H
H
H
H
L
L
X
X
X
X
X
X
X
L
L
L
L
L
H
L
X
X
X
X
X
X
L
H
L
L
H
L
H
L
X
X
X
X
X
L
H
H
L
H
L
L
H
L
X
X
X
X
L
H
H
H
L
H
H
L
H
L
X
X
X
L
H
H
H
H
H
L
L
L
H
L
X
X
L
H
H
H
H
H
H
L
H
L
H
L
X
L
H
H
H
H
H
H
H
H
L
L
H
L
L
H
H
H
H
H
H
H
H
H
H
L
H
M74HC148
3/11
ABSOLUTE MAXIMUM RATINGS
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
C; derate to 300mW by 10mW/
C from 65
C to 85
C
RECOMMENDED OPERATING CONDITIONS
Symbol
Parameter
Value
Unit
V
CC
Supply Voltage
-0.5 to +7
V
V
I
DC Input Voltage
-0.5 to V
CC
+ 0.5
V
V
O
DC Output Voltage
-0.5 to V
CC
+ 0.5
V
I
IK
DC Input Diode Current
20
mA
I
OK
DC Output Diode Current
20
mA
I
O
DC Output Current
25
mA
I
CC
or I
GND
DC V
CC
or Ground Current
50
mA
P
D
Power Dissipation
500(*)
mW
T
stg
Storage Temperature
-65 to +150
C
T
L
Lead Temperature (10 sec)
300
C
Symbol
Parameter
Value
Unit
V
CC
Supply Voltage
2 to 6
V
V
I
Input Voltage
0 to V
CC
V
V
O
Output Voltage
0 to V
CC
V
T
op
Operating Temperature
-55 to 125
C
t
r
, t
f
Input Rise and Fall Time
V
CC
= 2.0V
0 to 1000
ns
V
CC
= 4.5V
0 to 500
ns
V
CC
= 6.0V
0 to 400
ns
M74HC148
4/11
DC SPECIFICATIONS
Symbol
Parameter
Test Condition
Value
Unit
V
CC
(V)
T
A
= 25C
-40 to 85C
-55 to 125C
Min.
Typ.
Max.
Min.
Max.
Min.
Max.
V
IH
High Level Input
Voltage
2.0
1.5
1.5
1.5
V
4.5
3.15
3.15
3.15
6.0
4.2
4.2
4.2
V
IL
Low Level Input
Voltage
2.0
0.5
0.5
0.5
V
4.5
1.35
1.35
1.35
6.0
1.8
1.8
1.8
V
OH
High Level Output
Voltage
2.0
I
O
=-20
A
1.9
2.0
1.9
1.9
V
4.5
I
O
=-20
A
4.4
4.5
4.4
4.4
6.0
I
O
=-20
A
5.9
6.0
5.9
5.9
4.5
I
O
=-4.0 mA
4.18
4.31
4.13
4.10
6.0
I
O
=-5.2 mA
5.68
5.8
5.63
5.60
V
OL
Low Level Output
Voltage
2.0
I
O
=20
A
0.0
0.1
0.1
0.1
V
4.5
I
O
=20
A
0.0
0.1
0.1
0.1
6.0
I
O
=20
A
0.0
0.1
0.1
0.1
4.5
I
O
=4.0 mA
0.17
0.26
0.33
0.40
6.0
I
O
=5.2 mA
0.18
0.26
0.33
0.40
I
I
Input Leakage
Current
6.0
V
I
= V
CC
or GND
0.1
1
1
A
I
CC
Quiescent Supply
Current
6.0
V
I
= V
CC
or GND
4
40
80
A
M74HC148
5/11
AC ELECTRICAL CHARACTERISTICS (C
L
= 50 pF, Input t
r
= t
f
= 6ns)
CAPACITIVE CHARACTERISTICS
1) C
PD
is defined as the value of the IC's internal equivalent capacitance which is calculated from the operating current consumption without
load. (Refer to Test Circuit). Average operating current can be obtained by the following equation. I
CC(opr)
= C
PD
x V
CC
x f
IN
+ I
CC
Symbol
Parameter
Test Condition
Value
Unit
V
CC
(V)
T
A
= 25C
-40 to 85C
-55 to 125C
Min.
Typ.
Max.
Min.
Max.
Min.
Max.
t
TLH
t
THL
Output Transition
Time
2.0
30
75
95
110
ns
4.5
8
15
19
22
6.0
7
13
16
19
t
PLH
t
PHL
Propagation Delay
Time (In - A0, A1,
A2)
2.0
60
150
190
225
ns
4.5
19
30
38
45
6.0
16
26
32
38
t
PLH
t
PHL
Propagation Delay
Time (In - EO, GS)
2.0
60
150
190
225
ns
4.5
19
30
38
45
6.0
16
26
32
38
t
PLH
t
PHL
Propagation Delay
Time ( EI -EO)
2.0
40
115
145
175
ns
4.5
14
23
29
35
6.0
12
20
25
30
t
PLH
t
PHL
Propagation Delay
Time (EI -GS)
2.0
40
115
145
175
ns
4.5
14
23
29
35
6.0
12
20
25
30
t
PLH
t
PHL
Propagation Delay
Time (EI - A0, A1,
A2)
2.0
40
115
145
175
ns
4.5
14
23
29
35
6.0
12
20
25
30
Symbol
Parameter
Test Condition
Value
Unit
V
CC
(V)
T
A
= 25C
-40 to 85C
-55 to 125C
Min.
Typ.
Max.
Min.
Max.
Min.
Max.
C
IN
Input Capacitance
5.0
5
10
10
10
pF
C
PD
Power Dissipation
Capacitance (note
1)
5.0
60
pF
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