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74HC148 Datasheet PDF
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February 1988
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 cir-
cuitry (enable input EI and enable output EO) has been pro-
vided to allow octal expansion without the need for external
circuitry All data inputs and outputs are active at the low
logic level
All inputs are protected from damage due to static dis-
charge by internal diode clamps to VCC and ground
Features
Y Typical propagation delay 13 ns
Y Wide supply voltage range 2V – 6V
Connection Diagram
Dual-In-Line Package
Truth Table
Order Number MM54HC148 or MM74HC148
TL F 9390 – 1
Inputs
Outputs
EI 0 1 2 3 4 5 6 7 A2 A1 A0 GS EO
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 XXXXX LHH L H L L H
L XXXX LHHH L H H L H
L XXX LHHHH H L L L H
L XX LHHHHH H L H L H
L X LHHHHHH H H L L H
L LHHHHHHH H H H L H
H e High L e Low X e irrelevant
C1995 National Semiconductor Corporation TL F 9390
RRD-B30M105 Printed in U S A


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Absolute Maximum Ratings (Notes 1 2)
If Military Aerospace specified devices are required
please contact the National Semiconductor Sales
Office Distributors for availability and specifications
Supply Voltage (VCC)
DC Input Voltage (VIN)
DC Output Voltage (VOUT)
Clamp Diode Current (IIK IOK)
DC Output Current per pin (IOUT)
DC VCC or GND Current per pin (ICC)
Storage Temperature Range (TSTG)
Power Dissipation (PD)
(Note 3)
S O Package only
b0 5 to a7 0V
b1 5 to VCC a1 5V
b0 5 to VCC a0 5V
g20 mA
g25 mA
g50 mA
b65 C to a150 C
600 mW
500 mW
Lead Temperature (TL)
(Soldering 10 sec )
260 C
Operation Conditions
Min Max Units
Supply Voltage (VCC)
DC Input or Output Voltage
2
0
(VIN VOUT)
Operating Temperature Range (TA)
MM74HC
b40
6
VCC
a85
V
V
C
MM54HC
b55 a125 C
Input Rise or Fall Times
(tr tf)
VCC e 2 0V
VCC e 4 5V
VCC e 6 0V
1000
500
400
ns
ns
ns
DC Electrical Characteristics (Note 4)
Symbol
Parameter
Conditions
74HC
54HC
VCC TA e 25 C TA e b40 to 85 C TA e b55 to 125 C Units
Typ Guaranteed Limits
VIH Minimum High Level
Input Voltage
2 0V
4 5V
6 0V
15
3 15
42
15
3 15
42
15 V
3 15 V
42 V
VIL Maximum Low Level
Input Voltage
2 0V
4 5V
6 0V
05
1 35
18
05
1 35
18
05 V
1 35 V
18 V
VOH
Minimum High Level VIN e VIH or VIL
Output Voltage
lIOUTl s 20 mA
2 0V 2 0 1 9
4 5V 4 5 4 4
6 0V 6 0 5 9
19
44
59
19 V
44 V
59 V
VIN e VIH or VIL
lIOUTl s 4 0 mA
lIOUTl s 5 2 mA
4 5V 4 7 3 96
6 0V 5 2 5 48
VOL Maximum Low Level VIN e VIH or VIL
Output Voltage
lIOUTl s 20 mA
2 0V 0 0 1
4 5V 0 0 1
6 0V 0 0 1
3 84
5 34
01
01
01
37 V
52 V
01 V
01 V
01 V
VIN e VIH or VIL
lIOUTl s 4 0 mA
lIOUTl s 5 2 mA
4 5V 0 2 0 26
6 0V 0 2 0 26
IIN Maximum Input VIN e VCC or GND 6 0V
Current
g0 1
0 33
0 33
g1 0
04
04
g1 0
V
V
mA
ICC Maximum Quiescent VIN e VCC or GND 6 0V
Supply Current
IOUT e 0 mA
80
80
160 mA
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 derating plastic ‘‘N’’ package b12 mW C from 65 C to 85 C ceramic ‘‘J’’ package b12 mW C from 100 C to 125 C
Note 4 For a power supply of 5V g10% the worst case output voltages (VOH and VOL) occur for HC at 4 5V Thus the 4 5V values should be used when designing
with this supply Worst case VIH and VIL occur at VCC e 5 5V and 4 5V respectively (The VIH value at 5 5V is 3 85V ) The worst case leakage current (IIN ICC and
IOZ) occur for CMOS at the higher voltage and so the 6 0V values should be used
VIL limits are currently tested at 20% of VCC The above VIL specification (30% of VCC) will be implemented no later than Q1 CY’89
2


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AC Electrical Characteristics VCC e 5V TA e 25 C CL e 15 pF tr e tf e 6 ns
Symbol
Parameter
Conditions
Typ
tPHL tPLH
Maximum Propagation Delay
Any Input to Any Output
14
Units
ns
AC Electrical Characteristics VCC e 2 0V to 6 0V CL e 50 pF tr e tf e 6 ns (unless otherwise specified)
Symbol
Parameter
VCC
TA e 25 C
Typ
74HC
b40 C to a85 C
54HC
b55 C to a125 C
Guaranteed Limits
Units
tPHL tPLH
Inputs 0–7
to Outputs
A0 A1 A2
2 0V
140
4 5V
14
28
6 0V
24
175
35
30
210 ns
42 ns
36 ns
tPHL tPLH
Inputs 0–7
to
Output EO
2 0V
140
4 5V
15
28
6 0V
24
175
35
30
210 ns
42 ns
36 ns
tPHL tPLH
Inputs 0–7
to
Output GS
2 0V
160
4 5V
17
32
6 0V
27
200
40
34
240 ns
48 ns
41 ns
tPHL tPLH
Input EI
to Outputs
A0 A1 A2
2 0V
160
4 5V
17
32
6 0V
27
200
40
34
240 ns
48 ns
41 ns
tPHL tPLH
Input EI
to
Output GS
2 0V
100
4 5V
12
20
6 0V
17
125
25
21
150 ns
30 ns
26 ns
tPHL tPLH
Input EI
to
Output EO
2 0V
100
4 5V
12
20
6 0V
17
125
25
21
150 ns
30 ns
26 ns
tf tr
Maximum
2 0V
75
Output Rise
4 5V
7
15
and Fall Time
6 0V
13
95
19
16
110 ns
22 ns
19 ns
Cpd Power Dissipation
52
Capacitance (Note 5)
pF
Cin Maximum Input
Capacitance
5 10
10
Note 5 Cpd determines the no load dynamic power consumption and the no load dynamic current consumption
10
pF
3


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Logic Diagram
Physical Dimensions inches (millimeters)
TL F 9390 – 2
Ceramic Dual-In-Line Package (J)
Order Number MM54HC148 or MM74HC148
NS Package Number J16A
5


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Physical Dimensions inches (millimeters) (Continued)
Molded Dual-In-Line Package (N)
Order Number MM54HC148 or MM74HC148
NS Package Number N16E
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL
SEMICONDUCTOR CORPORATION As used herein
1 Life support devices or systems are devices or
systems which (a) are intended for surgical implant
into the body or (b) support or sustain life and whose
failure to perform when properly used in accordance
with instructions for use provided in the labeling can
be reasonably expected to result in a significant injury
to the user
2 A critical component is any component of a life
support device or system whose failure to perform can
be reasonably expected to cause the failure of the life
support device or system or to affect its safety or
effectiveness
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