3

5227E–SEEPR–11/08

AT24HC04B

1.

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

must be hardwired for the AT24HC04B. As many as four 4K devices may be addressed on a

single bus system. The A0 pin is a no-connect. (Device addressing and Page addressing are

discussed in detail under Device Addressing and Page Addressing, page 8).

WRITE PROTECT (WP): The AT24HC04B has a WP pin that provides hardware data protec-

tion. The WP pin allows normal read/write operations when connected to ground (GND). When

the WP pin is connected to V

Table 1-1.

Write Protect

WP Pin Status

Part of the Array Protected

24HC04B

Upper Half (2K) Array

At GND

Normal Read/Write Operations