AT24C128CSSUMB datasheet(3/22 Pages) ATMEL

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Atmel AT24C128C [DATASHEET]

8734B–SEEPR–9/2012

Block Diagram

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.

Device Addresses (A2, A1, A0): The A2, A1, and A0 pins are device address inputs that are hard wired (directly to GND

or to VCC) for compatibility with other Atmel AT24C devices. When the pins are hard wired, as many as eight 128K

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

are left floating, the A2, A1, and A0 pins will be internally pulled down to GND. However, due to capacitive coupling that

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

connected directly to VCC, all write operations to the memory are inhibited. If the pin is left floating, the WP pin will be

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

VCC

GND

SCL

SDA

EEPROM

OUT/ACK

LOGIC

COMP

LOAD

INC

Y DEC

R/W

OUT

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

At VCC

Full Array

At GND

Normal Read/Write Operations

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