M74HC148 [STMICROELECTRONICS]
8 TO 3 LINE PRIORITY ENCODER; 8至3线优先编码器
| 型号： | M74HC148 |
| 厂家： | 
ST |
| 描述： | 8 TO 3 LINE PRIORITY ENCODER |
| 文件： | 总11页 (文件大小：332K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
M74HC148
8 TO 3 LINE PRIORITY ENCODER
■
■
■
■
■
■
■
HIGH SPEED:
= 16ns (TYP.) at V = 6V
t
PD
CC
LOW POWER DISSIPATION:
= 4µA(MAX.) at T =25°C
I
CC
A
HIGH NOISE IMMUNITY:
= V = 28 % V (MIN.)
V
NIH
NIL
CC
DIP
SOP
TSSOP
T & R
SYMMETRICAL OUTPUT IMPEDANCE:
|I | = I = 4mA (MIN)
OH
OL
BALANCED PROPAGATION DELAYS:
t
t
ORDER CODES
PACKAGE
PLH
PHL
WIDE OPERATING VOLTAGE RANGE:
(OPR) = 2V to 6V
TUBE
V
CC
DIP
SOP
M74HC148B1R
M74HC148M1R
PIN AND FUNCTION COMPATIBLE WITH
74 SERIES 148
M74HC148RM13TR
M74HC148TTR
TSSOP
DESCRIPTION
The M74HC148 is an high speed CMOS 8 TO 3
LINE PRIORITY ENCODER fabricated with
silicon gate C MOS technology.
has been provided to allow octal expansion
without the need for external circuitry. Data inputs
are active at the low logic level.
2
The M74HC148 encodes eight data lines to
three-line (4-2-1) binary (octal). Cascading
circuitry (enable input EI and enable output EO)
All inputs are equipped with protection circuits
against static discharge and transient excess
voltage.
PIN CONNECTION AND IEC LOGIC SYMBOLS
July 2001
1/11
M74HC148
INPUT AND OUTPUT EQUIVALENT CIRCUIT
PIN DESCRIPTION
PIN No
SYMBOL
NAME AND FUNCTION
Data Outputs
9, 7, 6
A to A
0
2
10, 11, 12,
0 to 7
Data Inputs
13, 1, 2, 3, 4
15
5
EO
EI
Enable Output
Enable Input
14
8
GS
Priority Flag Output
Ground (0V)
GND
16
V
Positive Supply Voltage
CC
TRUTH TABLE
INPUTS
OUTPUTS
E1
0
1
2
3
4
5
6
7
A2
A1
A0
GS
E0
H
L
L
L
L
L
L
L
L
L
X
H
X
X
X
X
X
X
X
L
X
H
X
X
X
X
X
X
L
X
H
X
X
X
X
X
L
X
H
X
X
X
X
L
X
H
X
X
X
L
X
H
X
X
L
X
H
X
L
X
H
L
H
H
L
H
H
L
H
H
L
H
H
L
L
L
L
L
L
L
L
H
L
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
L
L
H
L
H
H
H
H
H
H
L
H
H
L
H
H
H
H
H
L
H
L
H
H
H
H
H
H
H
H
H
H
H
L
H
L
H
H
H
H
H
H
X : Don’t Care
LOGIC DIAGRAM
This logic diagram has not be used to estimate propagation delays
2/11
M74HC148
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
Unit
V
Supply Voltage
-0.5 to +7
V
V
CC
V
DC Input Voltage
-0.5 to V + 0.5
I
CC
V
DC Output Voltage
DC Input Diode Current
DC Output Diode Current
DC Output Current
-0.5 to V + 0.5
V
O
CC
I
± 20
± 20
mA
mA
mA
mA
mW
°C
IK
I
OK
I
± 25
O
I
or I
DC V
or Ground Current
CC
± 50
CC
GND
P
Power Dissipation
500(*)
-65 to +150
300
D
T
Storage Temperature
Lead Temperature (10 sec)
stg
T
°C
L
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
Supply Voltage
2 to 6
0 to V
V
V
CC
V
Input Voltage
I
CC
V
Output Voltage
0 to V
CC
V
O
T
Operating Temperature
Input Rise and Fall Time
-55 to 125
0 to 1000
0 to 500
0 to 400
°C
ns
ns
ns
op
V
V
V
= 2.0V
= 4.5V
= 6.0V
CC
CC
CC
t , t
r
f
3/11
M74HC148
DC SPECIFICATIONS
Test Condition
Value
T
= 25°C
Symbol
Parameter
-40 to 85°C -55 to 125°C Unit
A
V
CC
(V)
Min. Typ. Max. Min. Max. Min. Max.
V
High Level Input
Voltage
2.0
4.5
6.0
2.0
4.5
6.0
2.0
1.5
3.15
4.2
1.5
3.15
4.2
1.5
3.15
4.2
IH
V
V
V
Low Level Input
Voltage
0.5
1.35
1.8
0.5
1.35
1.8
0.5
1.35
1.8
IL
V
High Level Output
Voltage
I =-20 µA
1.9
4.4
5.9
2.0
4.5
6.0
1.9
4.4
1.9
4.4
OH
O
I =-20 µA
4.5
6.0
4.5
6.0
2.0
4.5
6.0
4.5
6.0
O
I =-20 µA
5.9
5.9
V
V
O
I =-4.0 mA
4.18 4.31
4.13
5.63
4.10
5.60
O
I =-5.2 mA
5.68
5.8
0.0
0.0
0.0
O
V
Low Level Output
Voltage
I =20 µA
0.1
0.1
0.1
0.1
0.1
0.1
0.1
OL
O
I =20 µA
O
I =20 µA
0.1
0.1
O
I =4.0 mA
0.17 0.26
0.18 0.26
0.33
0.33
0.40
0.40
O
I =5.2 mA
O
I
Input Leakage
Current
I
V = V
or GND
6.0
6.0
± 0.1
± 1
± 1
µA
µA
I
CC
CC
I
Quiescent Supply
Current
CC
V = V
or GND
4
40
80
I
4/11
M74HC148
AC ELECTRICAL CHARACTERISTICS (C = 50 pF, Input t = t = 6ns)
L
r
f
Test Condition
Value
-40 to 85°C -55 to 125°C Unit
T
= 25°C
Symbol
Parameter
A
V
CC
(V)
Min. Typ. Max. Min. Max. Min. Max.
t
t
Output Transition
Time
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
30
8
75
15
95
19
110
22
TLH THL
ns
ns
ns
ns
ns
ns
7
13
16
19
t
t
t
t
t
t
Propagation Delay
Time (In - A0, A1,
A2)
60
19
16
60
19
16
40
14
12
40
14
12
40
14
12
150
30
190
38
225
45
PLH PHL
26
32
38
t
Propagation Delay
Time (In - EO, GS)
150
30
190
38
225
45
PLH PHL
26
32
38
t
Propagation Delay
Time ( EI -EO)
115
23
145
29
175
35
PLH PHL
20
25
30
t
Propagation Delay
Time (EI -GS)
115
23
145
29
175
35
PLH PHL
20
25
30
t
Propagation Delay
Time (EI - A0, A1,
A2)
115
23
145
29
175
35
PLH PHL
20
25
30
CAPACITIVE CHARACTERISTICS
Test Condition
Value
-40 to 85°C -55 to 125°C Unit
T
= 25°C
Symbol
Parameter
A
V
CC
(V)
Min. Typ. Max. Min. Max. Min. Max.
C
Input Capacitance
5.0
5
10
10
10
pF
pF
IN
C
Power Dissipation
Capacitance (note
1)
PD
5.0
60
1) C is defined as the value of the IC’s internal equivalent capacitance which is calculated from the operating current consumption without
PD
load. (Refer to Test Circuit). Average operating current can be obtained by the following equation. I
= C x V x f + I
CC(opr)
PD CC IN CC
5/11
M74HC148
TEST CIRCUIT
C
R
= 50pF or equivalent (includes jig and probe capacitance)
L
T
= Z
of pulse generator (typically 50Ω)
OUT
WAVEFORM 1: PROPAGATION DELAY TIMES ,FOR INVERTING AND NON INVERTING OUTPUTS
(f=1MHz; 50% duty cycle)
6/11
M74HC148
TYPICAL APPLICATION
7/11
M74HC148
Plastic DIP-16 (0.25) MECHANICAL DATA
mm.
TYP
inch
TYP.
DIM.
MIN.
0.51
0.77
MAX.
MIN.
0.020
0.030
MAX.
a1
B
b
1.65
0.065
0.5
0.020
0.010
b1
D
E
e
0.25
20
0.787
8.5
2.54
17.78
0.335
0.100
0.700
e3
F
7.1
5.1
0.280
0.201
I
L
3.3
0.130
Z
1.27
0.050
P001C
8/11
M74HC148
SO-16 MECHANICAL DATA
mm.
inch
TYP.
DIM.
MIN.
TYP
MAX.
1.75
0.2
MIN.
MAX.
0.068
0.007
0.064
0.018
0.010
A
a1
a2
b
0.1
0.003
1.65
0.46
0.25
0.35
0.19
0.013
0.007
b1
C
0.5
0.019
c1
D
45° (typ.)
9.8
5.8
10
0.385
0.228
0.393
0.244
E
6.2
e
1.27
8.89
0.050
0.350
e3
F
3.8
4.6
0.5
4.0
5.3
0.149
0.181
0.019
0.157
0.208
0.050
0.024
G
L
1.27
0.62
M
S
8° (max.)
PO13H
9/11
M74HC148
TSSOP16 MECHANICAL DATA
mm.
inch
TYP.
DIM.
MIN.
TYP
MAX.
1.2
MIN.
MAX.
0.047
0.006
0.041
0.012
0.0089
0.201
0.260
0.176
A
A1
A2
b
0.05
0.8
0.15
1.05
0.30
0.20
5.1
0.002
0.031
0.007
0.004
0.193
0.244
0.169
0.004
0.039
1
0.19
0.09
4.9
c
D
5
6.4
0.197
0.252
E
6.2
6.6
E1
e
4.3
4.4
4.48
0.173
0.65 BSC
0.0256 BSC
K
0°
8°
0°
8°
L
0.45
0.60
0.75
0.018
0.024
0.030
A2
A
K
L
b
e
A1
c
E
D
E1
PIN 1 IDENTIFICATION
1
0080338D
10/11
M74HC148
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the
consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from
its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications
mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information
previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or
systems without express written approval of STMicroelectronics.
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11/11
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