BR24T128FVJ-WE2_ 查看數據表（PDF） - ROHM Semiconductor

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BR24T128FVJ-WE2_

High Reliability Serial EEPROMs I2C BUS BR24□□□□ family

ROHM Semiconductor 

BR24T□□□□Series

Technical Note

●WP valid timing (write cancel)

WP is usually fixed to 'H' or 'L', but when WP is used to cancel write cycle and so forth, pay attention to the following WP

valid timing. During write cycle execution, in cancel valid area, by setting WP='H', write cycle can be cancelled. In both byte

write cycle and page write cycle, the area from the first start condition of command to the rise of clock to taken in D0 of

data(in page write cycle, the first byte data) is cancel invalid area.

WP input in this area becomes Don't care. The area from the rise of SCL to take in D0 to input the stop condition is cancel

valid area. And, after execution of forced end by WP, standby status gets in.

・Rise of D0 taken clock

SCL

SDA

D1 D0 ACK

Enlarged view

・Rise of SDA

SCL

SDA D0 ACK

Enlarged view

SDA

WP

S

T Slave

A

R address

T

A

C Word

K

L

address

A

C

K

L

A

D7 D6 D5 D4 D3 D2 D1 D0 C

K

L

Data

AS

CT

KO

LP

tWR

WP cancel invalid area

WP cancel valid area WP cancel invalid area

Data is not written.

Fig.50 WP valid timing

●Command cancel by start condition and stop condition

During command input, by continuously inputting start condition and stop condition, command can be cancelled. (Fig.51)

However, in ACK output area and during data read, SDA bus may output 'L', and in this case, start condition and stop

condition cannot be input, so reset is not available. Therefore, execute software reset. And when command is cancelled by

start, stop condition, during random read cycle, sequential read cycle, or current read cycle, internal setting address is not

determined, therefore, it is not possible to carry out current read cycle in succession. When to carry out read cycle in

succession, carry out random read cycle.

SCL

SDA

1

0

1

0

Start condition Stop condition

Fig.51 Case of cancel by start, stop condition during slave address input

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© 2011 ROHM Co., Ltd. All rights reserved.

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2011.03 - Rev.A

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