1
FN8108.1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Copyright Intersil Americas Inc. 2005-2006. All Rights Reserved
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X28HC256
256K, 32K x 8 Bit
5 Volt, Byte Alterable EEPROM
FEATURES
Access time: 70ns
Simple byte and page write
—Single 5V supply
—No external high voltages or V
PP
control circuits
—Self-timed
—No erase before write
—No complex programming algorithms
—No overerase problem
Low power CMOS
—Active: 60mA
—Standby: 500μA
Software data protection
—Protects data against system level inadvertent
writes
High speed page write capability
Highly reliable Direct Write
cell
—Endurance: 1,000,000 cycles
—Data retention: 100 years
Early end of write detection
—DATA polling
—Toggle bit polling
Pb-free plus anneal available (RoHS compliant)
DESCRIPTION
The X28HC256 is a second generation high perfor-
mance CMOS 32K x 8 EEPROM. It is fabricated with
Intersil’s proprietary, textured poly floating gate tech-
nology, providing a highly reliable 5 Volt only nonvola-
tile memory.
The X28HC256 supports a 128-byte page write opera-
tion, effectively providing a 24μs/byte write cycle, and
enabling the entire memory to be typically rewritten in
less than 0.8 seconds. The X28HC256 also features
DATA Polling and Toggle Bit Polling, two methods of
providing early end of write detection. The X28HC256
also supports the JEDEC standard Software Data Pro-
tection feature for protecting against inadvertent writes
during power-up and power-down.
Endurance for the X28HC256 is specified as a mini-
mum 1,000,000 write cycles per byte and an inherent
data retention of 100 years.
BLOCK DIAGRAM
X Buffers
Latches and
Decoder
I/O Buffers
and Latches
Y Buffers
Latches and
DECODER
Control
Logic and
Timing
256Kbit
EEPROM
Array
I/O
0
–I/O
7
Data Inputs/Outputs
CE
OE
V
CC
V
SS
A
0
–A
14
Address
Inputs
WE
Data Sheet
May 17, 2006