BU9889GUL-W Rohm, BU9889GUL-W Datasheet - Page 11

• Manufacturer Part Number: BU9889GUL-W
• Description: WL-CSP EEPROM family I2C BUS
• Manufacturer: Rohm

●Software reset
●Acknowledge polling
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BU9889GUL-W
www.rohm.com
Software reset is executed when to avoid malfunction after power on, and to reset during command input. Software reset
has several kinds, and 3 kids of them are shown in the figure below. (Refer to Fig.38(a), Fig.38(b), Fig.38(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.
During internal write, 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 so forth.
SDA
SCL
SCL
SCL
SDA
SDA
…
S
T
A
R
T
Fig.385-(b) The case of START+9 Dummy clock + START + command input
First write command
Fig.38-(a) The case of 14 Dummy clock + START + START+ command input
Fig.38-(c) START × 9 + command input
S
T
A
R
T
Write command
Slave
address
Start
t
WR
Fig.39 Case to continuously write by acknowledge polling
1
1
A
C
K
H
2
1
2
Dummy clock×14
Dummy clock×9
S
T
O
P
Start×9
2
3
S
T
A
R
T
13
Slave
address
S
T
A
R
T
Slave
address
14
8
7
Second write command
A
C
K
L
After
write, ACK=LOW is sent back,
so input next word address and
data in succession.
Start×2
9
A
C
K
H
8
address
11/17
t
Word
WR
Start
During internal write,
ACK = HIGH is sent back.
completion
9
S
T
A
R
T
Slave
address
A
C
K
L
Data
of
A
C
K
H
* Start command from START input.
Normal command
Normal command
Normal command
Normal command
Normal command
Normal command
A
C
K
L
internal
…
S
T
O
P
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2010.01 - Rev.A
Technical Note