R1EX24512BSAS0I/R1EX24512BTAS0I

R10DS0026EJ0400 Rev.4.00

Page 8 of 17

Sep, 20, 2013

Functional Description

Start Condition

A high-to-low transition of the SDA with the SCL high is needed in order to start read, write operation (See start

condition and stop condition).

Stop Condition

A low-to-high transition of the SDA with the SCL high is a stop condition. The stand-by operation starts after a read

sequence by a stop condition. In the case of write operation, a stop condition terminates the write data inputs and place

the device in a internally-timed write cycle to the memories. After the internally-timed write cycle which is specified as

Start Condition and Stop Condition

SCL

SDA

(in)

Stop condition

Start condition

Acknowledge

All addresses and data words are serially transmitted to and from in 8-bit words. The receiver sends a zero to

acknowledge that it has received each word. This happens during ninth clock cycle. The transmitter keeps bus open to

receive acknowledgment from the receiver at the ninth clock. In the write operation, EEPROM sends a zero to

acknowledge after receiving every 8-bit words. In the read operation, EEPROM sends a zero to acknowledge after

receiving the device address word. After sending read data, the EEPROM waits acknowledgment by keeping bus open.

If the EEPROM receives zero as an acknowledge, it sends read data of next address. If the EEPROM receives

acknowledgment "1" (no acknowledgment) and a following stop condition, it stops the read operation and enters a

stand-by mode. If the EEPROM receives neither acknowledgment "0" nor a stop condition, the EEPROM keeps bus

open without sending read data.

Acknowledge Timing Waveform

SCL

SDA IN

SDA OUT

12

8

9

Acknowledge

out