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MM74HC148 8-3 Line Priority Encoder
October 1987 Revised September 2001
MM74HC148 8-3 Line Priority Encoder
General Description
The MM74HC148 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
s Typical propagation delay: 13 ns s Wide supply voltage range: 2V-6V
Ordering Code:
Order Number MM74HC148M MM74HC148N Package Number M16A N16E Package Description 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150" Narrow 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide
Connection Diagram
Truth Table
Inputs EI H L L L L L L L L L 0 1 2 3 4 5 6 XXXXXXXX HHHHHHHH XXXXXXXL XXXXXXLH XXXXXLHH XXXXLHHH XXXLHHHH XXLHHHHH XLHHHHHH LHHHHHHH H H L L L L H H H H Outputs 7 A2 A1 A0 GS EO H H L L H H L L H H H H L H L H L H L H H H L L L L L L L L H L H H H H H H H H
H = HIGH L = LOW X = Irrelevant
(c) 2001 Fairchild Semiconductor Corporation
DS009390
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MM74HC148
Schematic Diagram
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MM74HC148
Logic Diagram
3
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MM74HC148
Absolute Maximum Ratings(Note 1)
(Note 2) 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 Lead Temperature (TL) (Soldering 10 sec.) 260C 600 mW 500 mW
Operation Conditions
Min Max 6 VCC Units V V Supply Voltage (VCC) DC Input or Output Voltage (VIN, VOUT) Operating Temperature Range (TA) MM74HC MM54HC Input Rise or Fall Times (tr, tf) VCC = 2.0V VCC = 4.5V VCC = 6.0V 1000 500 400 ns ns ns 2 0
-0.5 to +7.0V -1.5 to VCC +1.5V -0.5 to VCC +0.5V 20 mA 25 mA 50 mA -65C to +150C
-40
+85
C C
-55 +125
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: -12 mW/C from 65C to 85C.
DC Electrical Characteristics
Symbol VIH Parameter Minimum HIGH Level Input Voltage VIL Maximum LOW Level Input Voltage (Note 5) VOH Minimum HIGH Level Output Voltage
(Note 4)
VCC 2.0V 4.5V 6.0V 2.0V 4.5V 6.0V TA = 25C Typ 1.5 3.15 4.2 0.5 1.35 1.8 2.0 4.5 6.0 4.7 5.2 0 0 0 0.2 0.2 1.9 4.4 5.9 3.96 5.48 0.1 0.1 0.1 0.26 0.26 0.1 8.0 TA = -40 to 85C 1.5 3.15 4.2 0.5 1.35 1.8 1.9 4.4 5.9 3.84 5.34 0.1 0.1 0.1 0.33 0.33 1.0 80 TA = -55 to 125C 1.5 3.15 4.2 0.5 1.35 1.8 1.9 4.4 5.9 3.7 5.2 0.1 0.1 0.1 0.4 0.4 1.0 160 Units V V V V V V V V V V V V V V V V A A
Conditions
Guaranteed Limits
VIN = VIH or VIL |IOUT| 20 A 2.0V 4.5V 6.0V VIN = VIH or VIL |IOUT| 4.0 mA |IOUT| 5.2 mA 4.5V 6.0V 2.0V 4.5V 6.0V VIN = VIH or VIL |IOUT| 4.0 mA |IOUT| 5.2 mA 4.5V 6.0V 6.0V 6.0V
VOL
Maximum LOW Level Output Voltage
VIN = VIH or VIL |IOUT| 20 A
IIN ICC
Maximum Input Current Maximum Quiescent Supply Current
VIN = VCC or GND VIN = VCC or GND IOUT = 0 A
Note 4: For a power supply of 5V 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 with this supply. Worst case VIH and VIL occur at VCC = 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. Note 5: VIL limits are currently tested at 20% of VCC.
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MM74HC148
AC Electrical Characteristics
Symbol tPHL, tPLH Parameter Maximum Propagation Delay, Any Input to Any Output Conditions Typ 14 Guaranteed Limits Units ns
AC Electrical Characteristics
VCC = 2.0V to 6.0V, CL = 50 pF, tr = tf = 6 ns (unless otherwise specified) Symbol tPHL, tPLH Inputs 0-7 to Outputs A0, A1, A2 tPHL, tPLH Inputs 0-7 to Output EO tPHL, tPLH Inputs 0-7 to Output GS tPHL, tPLH Input EI to Outputs A0, A1, A2 tPHL, tPLH Input EI to Output GS tPHL, tPLH Input EI to Output EO tf, tr Maximum Output Rise and Fall Time Cpd Cin Power Dissipation Capacitance (Note 6) Maximum Input Capacitance
Note 6: Cpd determines the no load dynamic power consumption, and the no load dynamic current consumption.
Parameter
VCC 2.0V 4.5V 6.0V 2.0V 4.5V 6.0V 2.0V 4.5V 6.0V 2.0V 4.5V 6.0V 2.0V 4.5V 6.0V 2.0V 4.5V 6.0V 2.0V 4.5V 6.0V
TA = 25C Typ 140 14 28 24 140 15 28 24 160 17 32 27 160 17 32 27 100 12 20 17 100 12 20 17 75 7 52 5 10 15 13
-40C to +85C 175 35 30 175 35 30 200 40 34 200 40 34 125 25 21 125 25 21 95 19 16
-55C to +125C 210 42 36 210 42 36 240 48 41 240 48 41 150 30 26 150 30 26 110 22 19
Guaranteed Limits
Units ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns pF
10
10
pF
5
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MM74HC148
Physical Dimensions inches (millimeters) unless otherwise noted
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150" Narrow Package Number M16A
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MM74HC148 8-3 Line Priority Encoder
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300" Wide Package Number N16E
Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and Fairchild reserves the right at any time without notice to change said circuitry and specifications. LIFE SUPPORT POLICY FAIRCHILD'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 FAIRCHILD 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 (c) 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. 7 2. A critical component in 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. www.fairchildsemi.com
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