1

1

2

3

4

8

7

6

5

CS

SO

WP

GND

VCC

HOLD

SCK

SI

8-lead PDIP

1

2

3

4

8

7

6

5

CS

SO

WP

GND

VCC

HOLD

SCK

SI

8-lead SOIC

1

2

3

4

8

7

6

5

CS

SO

WP

GND

VCC

HOLD

SCK

SI

8-lead TSSOP

1

2

3

4

8

7

6

5

VCC

HOLD

SCK

SI

CS

SO

WP

GND

8-lead SAP

VCC

HOLD

SCK

S

I

CS

SO

WP

GND

1

2

3

4

8

7

6

5

8-ball dBGA2

Bottom View

Bottom View

Features

– 2.7 (V

– 1.8 (V

– Protect 1/4, 1/2, or Entire Array

Both Hardware and Software Data Protection

– Endurance: 1 Million Write Cycles

– Data Retention: >100 Years

Devices Available

8-lead SAP Packages

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.

Table 1. 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

3368H–SEEPR–8/05

SPI Serial

EEPROMs

128K (16,384 x 8)

256K (32,768 x 8)

AT25128A

AT25256A