Features
• Serial Peripheral Interface (SPI) Compatible
• Supports SPI Modes 0 (0,0) and 3 (1,1)
• Low Voltage and Standard Voltage Operation
– 5.0 (VCC = 4.5V to 5.5V)
– 2.7 (VCC = 2.7V to 5.5V)
– 1.8 (VCC = 1.8V to 3.6V)
• 3 MHz Clock Rate
• 64-Byte Page Mode and Byte Write Operation
• Block Write Protection
– Protect 1/4, 1/2, or Entire Array
SPI Serial
EEPROMs
128K (16,384 x 8)
256K (32,768 x 8)
• 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
– ESD Protection: >4000V
• Automotive Grade and Extended Temperature Devices Available
• 8-Pin PDIP, 8-Pin EIAJ SOIC, 8-Pin and 16-Pin JEDEC SOIC, 14-Pin and 20-Pin TSSOP,
and 8-Pin Leadless Array Packages
AT25128
AT25256
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
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Pin Configurations
14-Lead TSSOP
Pin Name
Function
CS
Chip Select
CS
SO
1
2
3
4
5
6
7
14
13
12
11
10
9
VCC
HOLD
NC
SCK
SI
Serial Data Clock
Serial Data Input
Serial Data Output
Ground
NC
NC
NC
NC
NC
WP
GND
SCK
SI
SO
8
20-Lead TSSOP*
GND
VCC
WP
16-Pin SOIC
Power Supply
Write Protect
Suspends Serial Input
No Connect
NC
CS
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
NC
VCC
HOLD
HOLD
NC
CS
SO
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
VCC
HOLD
NC
SO
SO
HOLD
NC
NC
NC
NC
NC
NC
NC
NC
NC
WP
GND
DC
SCK
SI
NC
NC
DC
Don't Connect
WP
GND
SCK
SI
DC
NC
NC
8-Pin PDIP
8-Pin SOIC
8-Pin Leadless Array
VCC
HOLD
SCK
SI
8
7
6
5
1
2
3
4
CS
1
2
8
7
1
2
8
7
VCC
VCC
CS
SO
CS
SO
SO
HOLD
SCK
SI
HOLD
SCK
SI
WP
GND
3
4
6
5
3
4
6
5
WP
WP
GND
GND
Bottom View
Rev. 0872E–08/98
*Note: Pins 3, 4 and 17, 18 are internally connected for 14-lead TSSOP socket compatibility.
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