HN58X2402/58X2404/58X2408/58X2416/58X2432/58X2464

11

Acknowledge Timing Waveform

SCL

SDA IN

SDA OUT

12

8

9

Acknowledge

out

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 in the order of A2, A1, A0. 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 A2-A0 pin status. As for the 4kbit, 8kbit and

16kbit EEPROMs, whole or some bits of their device address code may be used as the memory address

bits. For example, A0 is used as a8 of memory address for the 4kbit, A0 and A1 are used as a8 and a9 for

the 8kbit. The 16kbit doesn't use the device address code instead all 3 bits are used as the memory address

bits a8, a9 and a10. 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 A2.

Device Address Word

Device address word (8-bit)

Device code (fixed)

Device address code*

1

R/W code*

2

2k, 32k, 64k 1010A2

A1

A0

R/W

4k

1010A2

A1

a8

R/W

8k

1010A2

a9

a8

R/W

16k

1010a10

a9

a8

R/W

Notes: 1. A2 to A0 are device address and a10 to a8 are memory address.

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