3

Atmel AT24C128C [DATASHEET]

8734B–SEEPR–9/2012

3.

Block Diagram

4.

Pin Descriptions

Serial Clock (SCL): The SCL input is used to positive-edge clock data into each EEPROM device and negative-edge

clock data out of each device.

Serial Data (SDA): The SDA pin is bidirectional for serial data transfer. This pin is open drain driven and may be

wire-ORed with any number of other open-drain or open-collector devices.

devices may be addressed on a single bus system. (Device addressing is discussed in detail in Section 7. “Device

Addressing” on page 9). A device is selected when a corresponding hardware and software match is true. If these pins

may appear during customer applications, Atmel recommends always connecting the address pins to a known state.

When using a pull-up resistor, Atmel recommends using 10k

 or less.

Write Protect (WP): The Write Protect input, when connected to GND, allows normal write operations. When WP is

internally pulled down to GND. However, due to capacitive coupling that may appear during customer applications, Atmel

recommends always connecting the WP pins to a known state. When using a pull-up resistor, Atmel recommends using

10k

 or less.

Table 4-1.

Write Protect

GND

WP

SCL

SDA

A

2

A

1

A

0

EN

EEPROM

D

LOGIC

COMP

LOAD

INC

Y DEC

R/W

D

OUT

D

IN

LOAD

Start

Stop

Logic

Serial

Control

Logic

H.V. Pump/Timing

Device

Address

Comparator

Data Word

Addr/Counter

Data Recovery

Serial MUX

WP Pin

Status

Part of the Array Protected

Atmel AT24C128C

Full Array

At GND

Normal Read/Write Operations