E
CAT28C256
256K-Bit Parallel EEPROM
TM
FEATURES
■ Hardware and software write protection
■ Fast read access times: 120/150ns
■ Automatic page write operation:
–1 to 64 bytes in 5ms
■ Low power CMOS dissipation:
–Active: 25 mA max
–Page load timer
–Standby: 150 µA max
■ End of write detection:
–Toggle bit
■ Simple write operation:
–On-chip address and data latches
–Self-timed write cycle with auto-clear
–DATA polling
■ 100,000 program/erase cycles
■ 100 year data retention
■ Fast write cycle time:
–5ms max
■ CMOS and TTL compatible I/O
■ Commerical, industrial and automotive
temperature ranges
DESCRIPTION
The CAT28C256 is a fast, low power, 5V-only CMOS
parallel EEPROM organized as 32K x 8-bits. It requires a
simple interface for in-system programming. On-chip
addressanddatalatches,self-timedwritecyclewithauto-
clear and VCC power up/down write protection eliminate
additional timing and protection hardware. DATA Polling
and Toggle status bits signal the start and end of the self-
timed write cycle. Additionally, the CAT28C256 features
hardware and software write protection.
The CAT28C256 is manufactured using Catalyst’s ad-
vancedCMOSfloatinggatetechnology. Itisdesignedto
endure 100,000 program/erase cycles and has a data
retention of 100 years. The device is available in JEDEC
approved 28-pin DIP, 28-pin TSOP or 32-pin PLCC
packages.
BLOCK DIAGRAM
32,768 x 8
EEPROM
ARRAY
ROW
DECODER
ADDR. BUFFER
A –A
6
14
& LATCHES
INADVERTENT
WRITE
PROTECTION
HIGH VOLTAGE
GENERATOR
64 BYTE PAGE
REGISTER
V
CC
CE
OE
WE
CONTROL
LOGIC
I/O BUFFERS
DATA POLLING
AND
TIMER
TOGGLE BIT
I/O –I/O
0
7
ADDR. BUFFER
& LATCHES
A –A
COLUMN
DECODER
0
5
Doc. No. 1004, Rev. D
© 2004 by Catalyst Semiconductor, Inc.
1
Characteristics subject to change without notice