DM74LS259 8-Bit Addressable Latches
August 1986
Revised March 2000
DM74LS259
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
Data-to-output
Clear-to-output
s
Fan-out
I
OL
(sink current)
s
Typical I
CC
22 mA
8 mA
I
OH
(source current)
鈭?.4
mA
18 ns
16 ns
17 ns
Address-to-output 21 ns
Ordering Code:
Order Number
DM74LS259M
DM74LS259WM
DM74LS259N
Package Number
M16A
M16B
N16E
Package Description
16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow
16-Lead Small Outline Intergrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide
Devices also available in Tape and Reel. Specify by appending the suffix letter 鈥淴鈥?to the ordering code.
漏 2000 Fairchild Semiconductor Corporation
DS006418
www.fairchildsemi.com
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