74LS259中文资料SYC数据手册PDF规格书

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 multifunctional

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 controlling

the clear and enable inputs as enumerated in the function

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

terminal is written into the addressed latch. The

addressed latch will follow the data input with all unaddressed

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 eliminate

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.

特性 Features

n 8-Bit parallel-out storage register performs serial-to-parallel

conversion with storage

n Asynchronous parallel clear

n Active high decoder

n Enable/disable input simplifies expansion

n Direct replacement for Fairchild DM9334

n Expandable for N-bit applications

n Four distinct functional modes

n Typical propagation delay times: