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)
• 3 MHz Clock Rate
• 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 Typical)
• High-reliability
– Endurance: 100,000 Write Cycles
– Data Retention: >200 Years
• Automotive Grade, Extended Temperature and Lead-Free Devices Available
• 8-lead PDIP, 8-lead EIAJ SOIC, 8-lead and 16-lead JEDEC SOIC, 14-lead and 20-lead
TSSOP, and 8-lead Leadless Array Packages
Description
The AT25128/256 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 (AT25128/256), 8-lead EIAJ SOIC (AT25128/256), 8-lead
and 16-lead JEDEC SOIC (AT25128), 14-lead TSSOP (AT25128), 20-lead TSSOP
(AT25128/256), and 8-lead Leadless Array (AT25256) 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.
Table 1. Pin Configuration
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
Rev. 0872O–SEEPR–03/05
*Note: Pins 3, 4 and 17, 18 are internally connected for 14-lead TSSOP socket compatibility.
SPI Serial
EEPROMs
128K (16,384 x 8)
256K (32,768 x 8)
AT25128
(1)
AT25256
(2)
Notes: 1. This device is not rec-
ommended for new
designs. Please refer
to AT25128A.
2. This device is not rec-
ommended for new
designs. Please refer
to AT25256A.
20-lead TSSOP*
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
NC
CS
SO
SO
NC
NC
WP
GND
DC
NC
NC
VCC
HOLD
HOLD
NC
NC
SCK
SI
DC
NC
8-lead PDIP
1
2
3
4
8
7
6
5
CS
SO
WP
GND
VCC
HOLD
SCK
SI
16-lead SOIC
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
CS
SO
NC
NC
NC
NC
WP
GND
VCC
HOLD
NC
NC
NC
NC
SCK
SI
14-lead TSSOP
1
2
3
4
5
6
7
14
13
12
11
10
9
8
CS
SO
NC
NC
NC
WP
GND
VCC
HOLD
NC
NC
NC
SCK
SI
8-lead Leadless Array
Bottom View
1
2
3
4
8
7
6
5
VCC
HOLD
SCK
SI
CS
SO
WP
GND