4位超前进位加法器

TL F 642154LS283 DM54LS283 DM74LS283 4-Bit Binary Adders with Fast Carry

June1989 54LS283 DM54LS283 DM74LS283

4-Bit Binary Adders with Fast Carry

General Description

These full adders perform the addition of two4-bit binary

numbers The sum(R)outputs are provided for each bit and

the resultant carry(C4)is obtained from the fourth bit

These adders feature full internal look ahead across all four

bits This provides the system designer with partial look-

ahead performance at the economy and reduced package

count of a ripple-carry implementation

The adder logic including the carry is implemented in its

true form meaning that the end-around carry can be accom-

plished without the need for logic or level inversion

Features

Y Full-carry look-ahead across the four bits

Y Systems achieve partial look-ahead performance with

the economy of ripple carry

Y Typical add times

Two8-bit words25ns

Two16-bit words45ns

Y Typical power dissipation per4-bit adder95mW

Y Alternate Military Aerospace device(54LS283)is avail-

able Contact a National Semiconductor Sales Office

Distributor for specifications

Connection Diagram

Dual-In-Line Package

TL F 6421–1

Order Number54LS283DMQB 54LS283FMQB 54LS283LMQB

DM54LS283J DM54LS283W DM74LS283M or DM74LS283N

See NS Package Number E20A J16A M16A N16E or W16A

C1995National Semiconductor Corporation RRD-B30M105 Printed in U S A

Absolute Maximum Ratings(Note)

If Military Aerospace specified devices are required please contact the National Semiconductor Sales Office Distributors for availability and specifications Supply Voltage7V Input Voltage7V Operating Free Air Temperature Range

DM54LS and54LS b55 C to a125 C DM74LS0 C to a70 C Storage Temperature Range b65 C to a150 C Note The‘‘Absolute Maximum Ratings’’are those values beyond which the safety of the device cannot be guaran-teed The device should not be operated at these limits The parametric values defined in the‘‘Electrical Characteristics’’table are not guaranteed at the absolute maximum ratings The‘‘Recommended Operating Conditions’’table will define the conditions for actual device operation

Recommended Operating Conditions

Symbol Parameter

DM54LS283DM74LS283

Units Min Nom Max Min Nom Max

V CC Supply Voltage4 555 54 7555 25V V IH High Level Input Voltage22V V IL Low Level Input Voltage0 70 8V I OH High Level Output Current b0 4b0 4mA I OL Low Level Output Current48mA T A Free Air Operating Temperature b55125070 C Electrical Characteristics over recommended operating free air temperature range(unless otherwise noted)

Symbol Parameter Conditions Min

Typ

Max Units (Note1)

V I Input Clamp Voltage V CC e Min I I e b18mA b1 5V V OH High Level Output V CC e Min I OH e Max DM542 53 4

V Voltage V IL e Max V IH e Min DM742 73 4

V OL Low Level Output V CC e Min I OL e Max DM540 250 4 Voltage V IL e Max V IH e Min DM740 350 5V

I OL e4mA V CC e Min DM740 250 4

I I Input Current Max V CC e Max A B0 2

mA Input Voltage V I e7V C00 1

I IH High Level Input V CC e Max A B40

m A Current V I e2 7V C020

I IL Low Level Input V CC e Max A B b0 8

mA Current V I e0 4V C0b0 4

I OS Short Circuit V CC e Max DM54b20b100

mA Output Current(Note2)DM74b20b100

I CC1Supply Current V CC e Max(Note3)1934mA I CC2Supply Current V CC e Max(Note4)2239mA Note1 All typicals are at V CC e5V T A e25 C

Note2 Not more than one output should be shorted at a time and the duration should not exceed one second

Note3 I CC1is measured with all outputs open all B inputs low and all other inputs at4 5V or all inputs at4 5V

Note4 I CC2is measured with all outputs open and all inputs grounded

2