R1EX24512ASAS0I

Device Addressing

The EEPROM device requires an 8-bit device address word following a start condition to enable the chip

for a read or a write operation. The device address word consists of 4-bit device code, 3-bit device

address code and 1-bit read/write(R/W) code. The most significant 4-bit of the device address word are

used to distinguish device type and this EEPROM uses “1010” fixed code. The device address word is

followed by the 3-bit device address code. The device address code selects one device out of all devices

which are connected to the bus. This means that the device is selected if the inputted 3-bit device address

code is equal to the corresponding hard-wired A1-A0 pin status. The eighth bit of the device address

word is the read/write(R/W) bit. A write operation is initiated if this bit is low and a read operation is

initiated if this bit is high. Upon a compare of the device address word, the EEPROM enters the read or

write operation after outputting the zero as an acknowledge. The EEPROM turns to a stand-by state if the

device code is not “1010” or device address code doesn’t coincide with status of the correspond hard-wired

device address pins A0 to A1.

Device Address Word

Device address word (8-bit)

Device code (fixed)

Device address code

R/W code*

1

512k

1

0

1

0

0*

2

A1

A0

R/W

Notes: 1. R/W=“1” is read and R/W = “0” is write.

2. Don’t care bit

REJ03C0330-0002 Rev.0.02 May. 16, 2008

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