Features
• Serial Peripheral Interface (SPI) Compatible
• Supports SPI Modes 0 (0,0) and 3 (1,1)
– Data Sheet Describes Mode 0 Operation
• Medium-voltage and Standard-voltage Operation
– 5.0 (VCC = 4.5V to 5.5V)
– 2.7 (VCC = 2.7V to 5.5V)
• 5 MHz Clock Rate
• 64-byte Page Mode and Byte Write Operation
• Block Write Protection
– Protect 1/4, 1/2, or Entire Array
SPI Serial
• Write Protect (WP) Pin and Write Disable Instructions for
both Hardware and Software Data Protection
• Self-timed Write Cycle (5 ms max)
• High Reliability
– Endurance: 100,000 Write Cycles
– Data Retention: >100 Years
• 8-lead PDIP and 8-lead JEDEC SOIC Packages
Automotive
EEPROMs
128K (16,384 x 8)
256K (32,768 x 8)
Description
The AT25128A/256A provides 131,072/262,144 bits of serial electrically-erasable pro-
grammable read-only memory (EEPROM) organized as 16,384/32,768 words of 8 bits
each. The device is optimized for use in many industrial and commercial applications
where low-power and low-voltage operation are essential. The devices are available in
space saving 8-lead PDIP and 8-lead JEDEC SOIC packages. In addition, the entire
family is available in 5.0V (4.5V to 5.5V) and 2.7V (2.7V to 5.5V) versions.
AT25128A
AT25256A
The AT25128A/256A is enabled through the Chip Select pin (CS) and accessed via a
three-wire interface consisting of Serial Data Input (SI), Serial Data Output (SO), and
Serial Clock (SCK). All programming cycles are completely self-timed, and no sepa-
rate erase cycle is required before write.
Block write protection is enabled by programming the status register with top one-
quarter, top one-half or entire array of write protection. Separate Program Enable and
Program Disable instructions are provided for additional data protection. Hardware
data protection is provided via the WP pin to protect against inadvertent write attempts
to the status register. The HOLD pin may be used to suspend any serial communica-
tion without resetting the serial sequence.
Table 1. Pin Configurations
Pin Name
CS
Function
8-lead PDIP
Chip Select
CS
SO
1
2
3
4
8
7
6
5
VCC
HOLD
SCK
SI
SCK
SI
Serial Data Clock
Serial Data Input
Serial Data Output
Ground
WP
SO
GND
GND
VCC
WP
Power Supply
Write Protect
Suspends Serial Input
No Connect
8-lead SOIC
CS
SO
1
2
3
4
8
7
6
5
VCC
HOLD
SCK
SI
HOLD
NC
WP
DC
Don't Connect
GND
Rev. 3404D–SEEPR–11/04
1