October 1987
Revised February 1999
MM74HC148
8-3 Line Priority Encoder
General Description
The MM74HC148 priority encoder utilizes advanced sili- con-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
■Typical propagation delay: 13 ns
■Wide supply voltage range: 2V–6V
Ordering Code:
Order Number |
Package Number |
Package Description |
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MM74HC148M |
M16A |
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150” Narrow |
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MM74HC148MTC |
MTC16 |
16-Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide |
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MM74HC148N |
N16E |
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” Wide |
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Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.
Connection Diagram |
Truth Table |
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Pin Assignments for DIP, SOIC and TSSOP |
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Inputs |
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Outputs |
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EI |
0 1 |
2 |
3 4 |
5 |
6 |
7 |
A2 A1 A0 |
GS EO |
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H |
X X |
X |
X X |
X |
X X |
H H H |
H H |
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L |
H H H H H H H H |
H H H |
H L |
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L |
X X |
X |
X X |
X |
X |
L |
L L L |
L H |
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L |
X X |
X |
X X |
X L |
H |
L L H |
L H |
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L |
X X |
X |
X X L H H |
L H L |
L H |
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L |
X X |
X |
X L H H H |
L H H |
L H |
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L |
X X |
X L H H H H |
H L L |
L H |
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L |
X X L H H H H H |
H L H |
L H |
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L |
X L H H H H H H |
H H L |
L H |
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L |
L H H H H H H H |
H H H |
L H |
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H = HIGH |
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L = LOW |
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X = Irrelevant |
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Encoder Priority Line 3-8 MM74HC148
© 1999 Fairchild Semiconductor Corporation |
DS009390.prf |
www.fairchildsemi.com |
MM74HC148
Schematic Diagram
www.fairchildsemi.com |
2 |
Logic Diagram
MM74HC148
3 |
www.fairchildsemi.com |
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