Features
• Serial Peripheral Interface (SPI) Compatible
• Supports SPI Modes 0 (0,0) and 3 (1,1)
• Data Sheet Describes Mode 0 Operation
• Low-voltage and Standard-voltage Operation
– 2.7 (VCC = 2.7V to 5.5V)
– 1.8 (VCC = 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: 1 Million Write Cycles
– Data Retention: >100 Years
• Automotive Grade, Extended Temperature and Lead-free/Halogen-free
Devices Available
SPI Serial
EEPROMs
128K (16,384 x 8)
256K (32,768 x 8)
• 8-lead PDIP, 8-lead EIAJ SOIC, 8-lead JEDEC SOIC, 8-lead TSSOP, 8-ball dBGA2 and
8-lead SAP Packages
• Die Sales: Wafer Form, Waffle Pack, and Bumped Die
AT25128A
AT25256A
Description
The AT25128A/256A provides 131,072/262,144 bits of serial electrically-erasable
programmable 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 appli-
cations 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, 8-ball dBGA2 and 8-lead SAP 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.
8-lead SOIC
8-lead PDIP
Table 1. Pin Configurations
CS
SO
1
2
3
4
8
7
6
5
VCC
HOLD
SCK
SI
CS
SO
1
2
3
4
8
7
6
5
VCC
HOLD
SCK
SI
Pin Name
CS
Function
WP
WP
GND
GND
Chip Select
SCK
SI
Serial Data Clock
Serial Data Input
Serial Data Output
Ground
8-lead SAP
8-lead TSSOP
VCC
8
7
6
5
1
2
3
4
CS
CS
SO
1
2
3
4
8
7
6
5
VCC
HOLD
SCK
SI
HOLD
SCK
SI
SO
SO
WP
GND
WP
GND
VCC
WP
GND
Bottom View
8-ball dBGA2
Power Supply
Write Protect
Suspends Serial Input
No Connect
8
7
6
5
1
2
3
4
CS
VCC
SO
HOLD
SCK
WP
GND
HOLD
NC
SI
Bottom View
3368H–SEEPR–8/05
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