3

8517C–SEEPR–01/09

AT24C01B/02B/04B/08B

4.

Pin Description

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 bi-directional 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/PAGE ADDRESSES (A2, A1, A0): The A2, A1 and A0 pins are device address inputs

that are hard wired for the AT24C01B/02B/04B. As many as eight 1K/2K devices may be

addressed on a single bus system (device addressing is discussed in detail under the Device

Addressing section). The AT24C04B uses the A2 and A1 inputs for hardwire addressing and a

total of four 4K devices may be addressed on a single bus system. The A0 pin is a no connect.

The AT24C08B only uses the A2 input for hardwire addressing and a total of two 8K devices

may be addressed on a single bus system. The A0 and A1 pins are no connect.

WRITE PROTECT (WP): The AT24C01B/02B/04B/08B has a Write Protect pin that provides

hardware data protection. The Write Protect pin allows normal read/write operations when con-

nected to ground (GND). When the Write Protect pin is connected to V

feature is enabled and operates as shown in the following table.

5.

Memory Organization

AT24C01B, 1K SERIAL EEPROM: Internally organized with 16 pages of 8 bytes each, the 1K

requires a 7-bit data word address for random word addressing.

AT24C02B, 2K SERIAL EEPROM: Internally organized with 32 pages of 8 bytes each, the 2K

requires an 8-bit data word address for random word addressing.

AT24C04B, 4K SERIAL EEPROM: Internally organized with 32 pages of 16 bytes each, the 4K

requires a 9-bit data word address for random word addressing.

AT24C08B, 8K SERIAL EEPROM: Internally organized with 64 pages of 16 bytes each, the 8K

requires a 10-bit data word address for random word addressing.

Table 4-1.

Write Protect

WP Pin

Status

Part of the Array Protected

AT24C01B/02B/04B/08B

Full Array

At GND

Normal Read/Write Operations