National Semiconductor MM54HC148, MM74HC148 Service Manual
MM54HC148/MM74HC148
8-3 Line Priority Encoder
General Description
This priority encoder utilizes advanced silicon-gate CMOS
technology. It has the high noise immunity and low power
consumption typical of CMOS circuits, as well as the speeds
and output drive similar to LB-TTL.
This priority encoder accepts 8 input request lines 0–7 and
outputs 3 lines A0–A2. The priority encoding ensures that
only the highest order data line is encoded. Cascading circuitry (enable input EI and enable output EO) has been provided to allow octal expansion without the need for external
circuitry. All data inputs and outputs are active at the low
logic level.
Connection Diagram
Dual-In-Line Package
February 1988
All inputs are protected from damage due to static discharge by internal diode clamps to V
and ground.
CC
Features
Y
Typical propagation delay: 13 ns
Y
Wide supply voltage range: 2V– 6V
MM54HC148/MM74HC148 8-3 Line Priority Encoder
Order Number MM54HC148 or MM74HC148
TL/F/9390– 1
Truth Table
Inputs Outputs
EI01234567A2A1A0GSEO
HXXXXXXXX H H H H H
L HHHHHHHH H H H H L
L XXXXXXXL L L L L H
L XXXXXXLH L L H L H
L XXXXXLHH L H L L H
LXXXXLHHHL H H L H
LXXXLHHHHH L L L H
L XX L HHHHH H L H L H
L XLHHHHHH H H L L H
L LHHHHHHH H H H L H
HeHigh, LeLow, Xeirrelevant
C
1995 National Semiconductor Corporation RRD-B30M105/Printed in U. S. A.
TL/F/9390
Absolute Maximum Ratings (Notes1&2)
Operation Conditions
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales
Office/Distributors for availability and specifications.
Supply Voltage (V
CC
)
DC Input Voltage (VIN)
DC Output Voltage (V
OUT
)
Clamp Diode Current (IIK,IOK)
DC Output Current, per pin (I
OUT
)
DC VCCor GND Current, per pin (ICC)
Storage Temperature Range (T
STG
b
b
)
b
0.5 toa7.0V
1.5 to V
CC
0.5 to V
CC
g
g
b
g
65§Ctoa150§C
a
1.5V
a
0.5V
20 mA
25 mA
50 mA
Power Dissipation (PD)
Supply Voltage (V
DC Input or Output Voltage 0 V
(V
IN,VOUT
Operating Temperature Range (T
)26V
CC
)
MM74HC
MM54HC
Input Rise or Fall Times
)V
V
V
e
2.0V 1000 ns
CC
e
4.5V 500 ns
CC
e
6.0V 400 ns
CC
(t
r,tf
(Note 3) 600 mW
S.O. Package only 500 mW
Lead Temperature (T
(Soldering 10 sec.) 260
)
L
C
§
DC Electrical Characteristics (Note 4)
Symbol Parameter Conditions V
CC
A
e
T
25§C
Typ Guaranteed Limits
V
Minimum High Level 2.0V 1.5 1.5 1.5 V
IH
Input Voltage 4.5V 3.15 3.15 3.15 V
6.0V 4.2 4.2 4.2 V
V
Maximum Low Level 2.0V 0.5 0.5 0.5 V
IL
Input Voltage** 4.5V 1.35 1.35 1.35 V
6.0V 1.8 1.8 1.8 V
V
Minimum High Level V
OH
Output Voltage
e
VIHor V
l
IN
I
OUT
IL
s
20 mA 2.0V 2.0 1.9 1.9 1.9 V
l
4.5V 4.5 4.4 4.4 4.4 V
6.0V 6.0 5.9 5.9 5.9 V
e
V
VIHor V
IN
I
l
OUT
I
l
OUT
l
IN
I
OUT
e
V
Maximum Low Level V
OL
Output Voltage
IL
s
4.0 mA 4.5V 4.7 3.96 3.84 3.7 V
l
s
5.2 mA 6.0V 5.2 5.48 5.34 5.2 V
l
VIHor V
IL
s
20 mA 2.0V 0 0.1 0.1 0.1 V
l
4.5V 0 0.1 0.1 0.1 V
6.0V 0 0.1 0.1 0.1 V
e
V
VIHor V
IN
I
l
OUT
I
l
OUT
I
IN
I
CC
Maximum Input V
Current
Maximum Quiescent V
Supply Current I
Note 1: Absolute Maximum Ratings are those values beyond which damage to the device may occur.
Note 2: Unless otherwise specified all voltages are referenced to ground.
Note 3: Power Dissipation temperature deratingÐplastic ‘‘N’’ package:
Note 4: For a power supply of 5V
with this supply. Worst case V
) occur for CMOS at the higher voltage and so the 6.0V values should be used.
I
OZ
**V
limits are currently tested at 20% of VCC. The above VILspecification (30% of VCC) will be implemented no later than Q1, CY’89.
IL
g
and VILoccur at V
IH
e
IN
e
IN
OUT
10% the worst case output voltages (VOH, and VOL) occur for HC at 4.5V. Thus the 4.5V values should be used when designing
IL
s
4.0 mA 4.5V 0.2 0.26 0.33 0.4 V
l
s
5.2 mA 6.0V 0.2 0.26 0.33 0.4 V
l
VCCor GND 6.0V
g
0.1
VCCor GND 6.0V 8.0 80 160 mA
e
0 mA
b
12 mW/§C from 65§Cto85§C, ceramic ‘‘J’’ package:b12 mW/§C from 100§Cto125§C.
e
5.5V and 4.5V respectively. (The VIHvalue at 5.5V is 3.85V.) The worst case leakage current (IIN,ICC, and
CC
74HC 54HC
eb
T
40 to 85§CT
A
g
1.0
Min Max Units
)
A
b40a
b55a
eb
55 to 125§C Units
A
g
1.0 mA
CC
85§C
125§C
V
2
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