74LS259

8-Bit Addressable Latches

General Description

These 8-bit addressable latches are designed for general

purpose storage applications in digital systems. Specific

uses include working registers, serial-holding registers,

and active-high decoders or demultiplexers. They are mul-

tifunctional devices capable of storing single-line data in

eight addressable latches, and being a 1-of-8 decoder or

demultiplexer with active-high outputs.

Four distinct modes of operation are selectable by control-

ling the clear and enable inputs as enumerated in the func-

tion table. In the addressable-latch mode, data at the data-

in terminal is written into the addressed latch. The

addressed latch will follow the data input with all unad-

dressed latches remaining in their previous states. In the

memory mode, all latches remain in their previous states

and are unaffected by the data or address inputs. To elimi-

nate the possibility of entering erroneous data in the

latches, the enable should be held HIGH (inactive) while

the address lines are changing. In the 1-of-8 decoding or

demultiplexing mode, the addressed output will follow the

level of the D input with all other outputs LOW. In the clear

mode, all outputs are LOW and unaffected by the address

and data inputs.

Features

s 8-Bit parallel-out storage register performs serial-to-par-

allel conversion with storage

s Asynchronous parallel clear

s Active high decoder

s Enable/disable input simplifies expansion

s Direct replacement for Fairchild DM9334

s Expandable for N-bit applications

s Four distinct functional modes

s Typical propagation delay times:

Enable-to-output

18 ns

Data-to-output

16 ns

Address-to-output 21 ns

Clear-to-output

17 ns

s Fan-out

IOL (sink current)

8 mA

IOH (source current) −0.4 mA

s Typical ICC

22 mA

Ordering Code:

Devices also available in Tape and Reel. Specify by appending the suffix letter “X” to the ordering code.

Order Number

Package Number

Package Description

DM74LS259M

M16A

16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow

DM74LS259WM

M16B

16-Lead Small Outline Intergrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide

DM74LS259N

N16E

16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide

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