BU9847GUL-W_12 Datasheet, PDF (16/28 Pages) Rohm – WLCSP EEPROM

BU9847GUL-W (4Kbit)
Datasheet
●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 40-(a), Figure 40-(b) and Figure
40-(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
Dummy clock x14
12
13 14
Start x2
Normal command
SDA
Normal command
Figure 40-(a) The case of dummy clock + START + START + command input
SCL
SDA
Start
Dummy clock x9
12
8
Start
9
Normal command
Normal command
Figure 40-(b) The case of START + 9 dummy clocks + START + command input
SCL
SDA
Start x 9
1 23
7 89
Normal command
Normal command
Figure 40-(c) START x 9 + command input
* Start normal command from START input.
●Acknowledge polling
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
T
A
R
T
Write command
S
T
O
P
S
T
A
R
T
Slave A
C
address _K
H
S
T
A
R
T
Slave
address
A
C
K
H
…
tWR
Second write command
S
…
T Slave ^A
A
R
T
C
address K
H
tWR
S
T
A
Slave
A
C
Word
A
C
R ^{address K address K}
T
L
L
Data
AS
CT
KO
LP
After completion of internal write,
ACK = LOW is sent back, so input
next word address and data in
succession.
Figure 41. Case to continuously write by acknowledge polling
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TSZ22111・15・001
16/24
TSZ02201-0R2R0G100480-1-2
4.SEP.2012 Rev.001