3
AT24C01A/02/04/08A/16A
0180V–SEEPR–8/05
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, A1 and A0 pins are device
address inputs that are hard wired for the AT24C01A and the AT24C02. 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 AT24C04 uses the A2 and A1 inputs for hard wire addressing and a total of four 4K
devices may be addressed on a single bus system. The A0 pin is a no connect.
The AT24C08A 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
connects.
The AT24C16A does not use the device address pins, which limits the number of
devices on a single bus to one. The A0, A1 and A2 pins are no connects.
WRITE PROTECT (WP): The AT24C01A/02/04/08A/16A has a Write Protect pin that
provides hardware data protection. The Write Protect pin allows normal Read/Write
operations when connected to ground (GND). When the Write Protect pin is connected
to V
CC
, the write protection feature is enabled and operates as shown in Table 2.
Table 2. Write Protect
Memory Organization AT24C01A, 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.
AT24C02, 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.
AT24C04, 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.
AT24C08A, 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.
AT24C16A, 16K SERIAL EEPROM: Internally organized with 128 pages of 16 bytes
each, the 16K requires an 11-bit data word address for random word addressing.
WP Pin
Status
Part of the Array Protected
24C01A 24C02 24C04 24C08A 24C16A
At V
CC
Full (1K)
Array
Full (2K)
Array
Full (4K)
Array
Full (8K)
Array
Full (16K)
Array
At GND Normal Read/Write Operations
