BR24T256FJ-W データシートの表示（PDF） - ROHM Semiconductor

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BR24T256FJ-W

Serial EEPROM Series Standard EEPROM I2C BUS EEPROM (2-Wire)

ROHM Semiconductor 

BR24T256-W

Datasheet

Software Reset

Software reset is executed to avoid malfunction after power on and during command input. Software reset has several kinds

and 3 kinds of them are shown in the figure below. (Refer to Figure 40-(a), Figure 40-(b), and Figure 40-(c).) Within the dummy

clock input area, the SDA bus is released ('H' by pull up) and ACK output and read data '0' (both 'L' level) may be output from

EEPROM. Therefore, if 'H' is input forcibly, output may conflict and over current may flow, leading to instantaneous power

failure of system power source or influence upon devices.

SCL

SDA

Dummy clock×14

Start×2

12

13 14

Normal command

Normal command

Figure 40-(a). The Case of Dummy Clock×14 + START+START+ Command Input

SCL

SDA

Start

Dummy clock×9

12

8

Start

9

Normal command

Normal command

Figure 40-(b). The Case of START + Dummy Clock×9 + START + Command Input

SCL

SDSAD

A

Start×9

1 23

7 89

Normal command

Normal command

Figure 40-(c). START×9 + Command Input

*Start command from START input.

Acknowledge Polling

During internal write execution, all input commands are ignored, therefore ACK is not returned. During internal automatic

write execution after write cycle input, next command (slave address) is sent. If the first ACK signal sends back 'L', then it

means end of write operation, else 'H' is returned, which means writing is still in progress. By the use of acknowledge polling,

next command can be executed without waiting for tWR = 5ms.

To write continuously, R / W = 0, then to carry out current read cycle after write, slave address with R / W = 1 is sent. If ACK

signal sends back 'L', and then execute word address input and data output and so forth..

First write command

During internal write,

ACK = HIGH is returned.

S

S

T

T

A Write command O

R

P

T

S

T Slave

A

R address

A

C

K

H

T

S

T Slave

A

R address

A

C

K

H

···

T

tWR

Second write command

···

S

T Slave

A

R

address

A

C

K

H

T

tWR

S

T Slave

A

R address

A

C

K

L

Word

address

A

C

K

L

Data

T

AS

CT

KO

LP

After completion of internal write,

ACK=LOW is returned, so input next

word address and data in succession.

Figure 41. Case of Continuous Write by Acknowledge Polling

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17.Dec.2018 Rev.004

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