BR24G04FJ-3A データシートの表示（PDF） - ROHM Semiconductor

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BR24G04FJ-3A

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

ROHM Semiconductor 

BR24G04-3A

●Software Reset

Software reset is executed when to avoid malfunction after power on, and to reset during command input. Software reset

has several kinds, and 3 kinds of them are shown in the figure below. (Refer to Figure 41-(a), Figure 41-(b), Figure 41-(c))

In dummy clock input area, release the SDA bus ('H' by pull up). In dummy clock area, 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 x 14

Start x 2

12

13 14

Normal command

Normal command

SCL

SDA

Figure 41-(a). Dummy clock x 14 + START + START + command input

Start

Dummy clock x 9

Start

12

89

Normal command

Normal command

SCL

SDA

Figure 41-(b). START + dummy clock x 9 + START + command input

Start x 9

1 23

7 89

Normal command

Normal command

●Acknowledge Polling

Figure 41-(c). START x 9 + command input

※Start command from START input.

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

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

it means end of write action, while if it sends back 'H', it means now in writing. By use of acknowledge polling, next

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

When to write continuously, R/W = 0, when to carry out current read cycle after write, slave address R/W = 1 is sent, and if

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

First write command

During internal write,

ACK = HIGH is sent back.

S

S

T

T

A Write command O

R

P

T

S

T Slave

A

R address

A

C

K

H

S

T Slave

A

R address

A

C

K

H

…

T

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 sent back, so input

next word address and data in

succession.

Figure 42. Case to continuously write by acknowledge polling

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