M74HC148
8 TO 3 LINE PRIORITY ENCODER
s
s
s
s
s
s
s
HIGH SPEED:
t
PD
= 16ns (TYP.) at V
CC
= 6V
LOW POWER DISSIPATION:
I
CC
= 4µA(MAX.) at T
A
=25°C
HIGH NOISE IMMUNITY:
V
NIH
= V
NIL
= 28 % V
CC
(MIN.)
SYMMETRICAL OUTPUT IMPEDANCE:
|I
OH
| = I
OL
= 4mA (MIN)
BALANCED PROPAGATION DELAYS:
t
PLH
≅
t
PHL
WIDE OPERATING VOLTAGE RANGE:
V
CC
(OPR) = 2V to 6V
PIN AND FUNCTION COMPATIBLE WITH
74 SERIES 148
DIP
SOP
ORDER CODES
PACKAGE
DIP
SOP
TSSOP
TUBE
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)
bs
O
et
l
o
ro
P
e
uc
d
s)
t(
O
-
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.
so
b
te
le
M74HC148B1R
M74HC148M1R
ro
P
uc
d
s)
t(
TSSOP
T&R
M74HC148RM13TR
M74HC148TTR
PIN CONNECTION AND IEC LOGIC SYMBOLS
July 2001
1/11
M74HC148
INPUT AND OUTPUT EQUIVALENT CIRCUIT
PIN DESCRIPTION
PIN No
9, 7, 6
10, 11, 12,
13, 1, 2, 3, 4
15
5
14
8
16
SYMBOL
A
0
to A
2
0 to 7
EO
EI
GS
GND
V
CC
NAME AND FUNCTION
Data Outputs
Data Inputs
Enable Output
Enable Input
Priority Flag Output
Ground (0V)
Positive Supply Voltage
TRUTH TABLE
INPUTS
E1
H
L
L
L
L
L
L
L
L
L
0
X
H
X
X
X
X
X
X
X
L
1
X
H
X
X
X
X
X
X
L
H
2
X
H
X
X
X
X
X
L
H
H
3
X
H
X
X
X
X
L
H
H
H
4
X
H
X
X
X
L
H
H
H
H
5
X
H
X
X
L
H
H
H
H
H
6
X
H
X
L
H
H
H
H
H
H
7
X
H
L
H
H
H
H
H
H
H
A2
H
H
L
L
L
L
H
H
H
H
A1
H
H
L
L
H
H
L
L
H
H
OUTPUTS
X : Don’t Care
LOGIC DIAGRAM
bs
O
et
l
o
ro
P
e
uc
d
s)
t(
O
-
so
b
te
le
ro
P
uc
d
A0
H
H
L
H
L
H
L
H
L
H
s)
t(
E0
H
L
H
H
H
H
H
H
H
H
H
H
L
L
L
L
L
L
L
L
GS
This logic diagram has not be used to estimate propagation delays
2/11
M74HC148
ABSOLUTE MAXIMUM RATINGS
Symbol
V
CC
V
I
V
O
I
IK
I
OK
I
O
Supply Voltage
DC Input Voltage
DC Output Voltage
DC Input Diode Current
DC Output Diode Current
DC Output Current
Parameter
Value
-0.5 to +7
-0.5 to V
CC
+ 0.5
-0.5 to V
CC
+ 0.5
±
20
±
20
±
25
±
50
500(*)
-65 to +150
300
Unit
V
V
V
mA
mA
mA
mA
I
CC
or I
GND
DC V
CC
or Ground Current
P
D
Power Dissipation
T
stg
T
L
Storage Temperature
Lead Temperature (10 sec)
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
V
CC
V
I
V
O
T
op
t
r
, t
f
Supply Voltage
Input Voltage
Output Voltage
Operating Temperature
Input Rise and Fall Time
Parameter
bs
O
et
l
o
ro
P
e
uc
d
)-
(s
t
b
O
so
te
le
r
P
du
o
Value
2 to 6
ct
s)
(
mW
°C
°C
Unit
V
V
V
°C
ns
ns
ns
0 to V
CC
0 to V
CC
-55 to 125
0 to 1000
0 to 500
0 to 400
V
CC
= 2.0V
V
CC
= 4.5V
V
CC
= 6.0V
3/11
M74HC148
AC ELECTRICAL CHARACTERISTICS
(C
L
= 50 pF, Input t
r
= t
f
= 6ns)
Test Condition
Symbol
Parameter
V
CC
(V)
2.0
4.5
6.0
2.0
4.5
6.0
2.0
4.5
6.0
2.0
4.5
6.0
2.0
4.5
6.0
2.0
4.5
6.0
T
A
= 25°C
Min.
Typ.
30
8
7
60
19
16
60
19
16
40
14
12
40
14
12
40
14
12
Max.
75
15
13
150
30
26
150
30
26
115
23
20
115
23
20
115
23
20
Value
-40 to 85°C
Min.
Max.
95
19
16
190
38
32
190
38
32
145
29
25
145
29
25
145
29
25
-55 to 125°C
Min.
Max.
110
22
19
225
45
38
225
45
38
175
35
30
175
35
30
175
35
30
ns
Unit
t
TLH
t
THL
Output Transition
Time
t
PLH
t
PHL
Propagation Delay
Time (In - A0, A1,
A2)
t
PLH
t
PHL
Propagation Delay
Time (In - EO, GS)
t
PLH
t
PHL
Propagation Delay
Time ( EI -EO)
t
PLH
t
PHL
Propagation Delay
Time (EI -GS)
t
PLH
t
PHL
Propagation Delay
Time (EI - A0, A1,
A2)
ns
CAPACITIVE CHARACTERISTICS
Symbol
Parameter
C
IN
C
PD
Input Capacitance
b
O
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
et
l
so
Power Dissipation
Capacitance (note
1)
ro
P
e
uc
d
V
CC
(V)
5.0
5.0
Test Condition
T
A
= 25°C
Min.
Typ.
5
60
Max.
10
s)
t(
O
-
so
b
te
le
ro
P
uc
d
s)
t(
ns
ns
ns
ns
Value
-40 to 85°C
Min.
Max.
10
-55 to 125°C
Min.
Max.
10
pF
pF
Unit
5/11
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