HD74HC148
8-to-3-line Octal Priority Encoder
ADE-205-447 (Z)
1st. Edition
Sep. 2000
Description
The HD74HC148 encodes eight data lines to three-line (4-2-1) binary (octal). Cascading circuitry (enable
input EI and enable output EO) is provided to allow octal expansion without the need for external circuitry.
The data inputs and outputs are active at the low logic level.
Features
•
High Speed Operation: t
pd
(0 - 7 to A
0
- A
2
) = 15 ns typ (C
L
= 50 pF)
•
High Output Current: Fanout of 10 LSTTL Loads
•
Wide Operating Voltage: V
CC
= 2 to 6 V
•
Low Input Current: 1 µA max
•
Low Quiescent Supply Current: I
CC
(static) = 4 µA max (Ta = 25°C)
Function Table
Inputs
EI
H
L
L
L
L
L
L
L
L
L
H :
L :
X :
0
X
H
X
X
X
X
X
X
X
L
1
X
H
X
X
X
X
X
X
L
H
High level
Low level
Irrelevant
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
Outputs
A
2
H
H
L
L
L
L
H
H
H
H
A
1
H
H
L
L
H
H
L
L
H
H
A
0
H
H
L
H
L
H
L
H
L
H
GS
H
H
L
L
L
L
L
L
L
L
EO
H
L
H
H
H
H
H
H
H
H
HD74HC148
Pin Arrangement
4 1
5 2
Inputs
6 3
7 4
EI 5
A
2
6
Outputs
A
1
7
GND 8
(Top view)
A
1
A
0
0
5
6
7
EI
A
2
4
EO
GS
3
2
1
16 V
CC
15 EO
Outputs
14 GS
13 3
12 2
Inputs
11 1
10 0
9 A
0
Output
2
HD74HC148
DC Characteristics
Ta = 25°C
Item
Input voltage
Symbol
V
IH
Ta = –40 to
+85°C
Max
—
—
—
0.5
1.35
1.8
—
—
—
—
—
0.1
0.1
0.1
0.33
0.33
±1.0
40
µA
µA
I
OL
= 4 mA
I
OL
= 5.2 mA
Vin = V
CC
or GND
Vin = V
CC
or GND, Iout = 0
µA
V
I
OH
= –4 mA
I
OH
= –5.2 mA
Vin = V
IH
or V
IL
I
OL
= 20
µA
V
Vin = V
IH
or V
IL
I
OH
= –20
µA
V
Unit
V
Test Conditions
V
CC
(V) Min Typ Max Min
2.0
4.5
6.0
1.5 —
3.15 —
4.2 —
—
—
—
—
—
—
—
—
—
0.5
1.5
3.15
4.2
—
V
IL
2.0
4.5
6.0
1.35 —
1.8
—
1.9
4.4
5.9
4.13
5.63
—
—
—
Output voltage
V
OH
2.0
4.5
6.0
4.5
6.0
1.9 2.0 —
4.4 4.5 —
5.9 6.0 —
4.18 —
5.68 —
—
—
—
—
—
—
—
—
—
V
OL
2.0
4.5
6.0
4.5
6.0
0.0 0.1
0.0 0.1
0.0 0.1
—
—
—
—
0.26 —
0.26 —
±0.1
—
4.0
—
Input current
Quiescent supply
current
Iin
I
CC
6.0
6.0
3
HD74HC148
AC Characteristics
(C
L
= 50 pF, Input t
r
= t
f
= 6 ns)
Ta = 25°C
Item
Symbol
Ta = –40 to
+85°C
Max
290
58
49
315
63
54
340
68
58
290
58
49
315
63
54
340
68
58
90
19
16
10
pF
ns
ns
EI to EO
ns
EI to GS
ns
EI to A
0
- A
2
ns
0 - 7 to GS
ns
0 - 7 to EO
Unit
ns
Test Conditions
0 - 7 to A
0
- A
2
V
CC
(V) Min Typ Max Min
2.0
4.5
6.0
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
15
—
—
16
—
—
18
—
—
12
—
—
12
—
—
12
—
—
5
—
5
230 —
46
39
—
—
Propagation delay t
PLH
time
t
PHL
t
PLH
t
PHL
2.0
4.5
6.0
250 —
50
43
—
—
t
PLH
t
PHL
2.0
4.5
6.0
270 —
54
46
—
—
t
PLH
t
PHL
2.0
4.5
6.0
230 —
46
39
—
—
t
PLH
t
PHL
2.0
4.5
6.0
250 —
50
43
—
—
t
PLH
t
PHL
2.0
4.5
6.0
270 —
54
46
75
15
13
10
—
—
—
—
—
—
Output rise/fall
time
t
TLH
t
THL
2.0
4.5
6.0
Input capacitance
Cin
—
4
HD74HC148
Package Dimensions
Unit: mm
19.20
20.00 Max
16
9
1
1.3
1.11 Max
8
7.40 Max
6.30
0.51 Min
2.54 Min 5.06 Max
7.62
2.54
±
0.25
0.48
±
0.10
0.25
– 0.05
0° – 15°
Hitachi Code
JEDEC
EIAJ
Mass (reference value)
+ 0.13
DP-16
Conforms
Conforms
1.07 g
Unit: mm
10.06
10.5 Max
16
9
1
*0.22
±
0.05
0.20
±
0.04
8
0.80 Max
5.5
0.20
7.80
+ 0.30
–
2.20 Max
1.15
0° – 8°
0.70
±
0.20
1.27
*0.42
±
0.08
0.40
±
0.06
0.12 M
Hitachi Code
JEDEC
EIAJ
Mass (reference value)
FP-16DA
—
Conforms
0.24 g
*Dimension including the plating thickness
Base material dimension
0.10
±
0.10
0.15
5
