1
8-lead SOIC
1
2
3
4
8
7
6
5
CS
SO
WP
GND
VCC
HOLD
SCK
SI
Features
• Serial Peripheral Interface (SPI) Compatible
• Supports SPI Modes 0 (0,0) and 3 (1,1)
• Low-voltage and Standard-voltage Operation
– 2.7 (V
CC
= 2.7V to 5.5V)
– 1.8 (V
CC
= 1.8V to 5.5V)
• 20 MHz Clock Rate (5V)
• 64-byte Page Mode and Byte Write Operation
• Block Write Protection
– Protect 1/4, 1/2, or Entire Array
• 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
• Automotive Grade, Extended Temperature and Lead-free/Halogen-free
Devices Available
• 8-lead PDIP, 8-lead EIAJ SOIC, 8-lead JEDEC SOIC, 8-lead TSSOP
and 8-ball dBGA2
™
Packages
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, 8-lead EIAJ SOIC, 8-lead JEDEC SOIC, 8-lead TSSOP
and 8-ball dBGA2 packages. In addition, the entire family is available in 2.7V (2.7V to
5.5V) and 1.8V (1.8V to 5.5V) versions.
The AT25128A/256A is enabled through the Chip Select pin (CS
) and accessed via a
3-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.
Rev. 3368D–SEEPR–6/04
SPI Serial
EEPROMs
128K (16,384 x 8)
256K (32,768 x 8)
AT25128A
AT25256A
Preliminary
Pin Configurations
Pin Name Function
CS
Chip Select
SCK Serial Data Clock
SI Serial Data Input
SO Serial Data Output
GND Ground
VCC Power Supply
WP
Write Protect
HOLD Suspends Serial Input
NC No Connect
DC Don't Connect
8-lead PDIP
1
2
3
4
8
7
6
5
CS
SO
WP
GND
VCC
HOLD
SCK
SI
8-ball dBGA2
Bottom View
VCC
HOLD
SCK
SI
CS
SO
WP
GND
1
2
3
4
8
7
6
5
8-lead TSSOP
1
2
3
4
8
7
6
5
CS
SO
WP
GND
VCC
HOLD
SCK
SI