Document
MM54HC148 MM74HC148 8-3 Line Priority Encoder
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 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
All inputs are protected from damage due to static discharge 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
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
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.