Datasheet
Technical Note
8/18
BR25S□□□ Series
www.rohm.com
2010.12 - Rev.B
© 2010 ROHM Co., Ltd. All rights reserved.
●Command mode
Command Contents Ope code
WREN Write enable command 0000 0110
WRDI Write disable command 0000 0100
READ Read command 0000 0011
WRITE Write command 0000 0010
RDSR Read status register command 0000 0101
WRSR Write status register command 0000 0001
●Timing chart
1. Write enable (WREN) / disable (WRDI) command
This IC has write enable status and write disable status. It is set to write enable status by write enable command, and it is
set to write disable status by write disable command. As for these commands, set CSB LOW, and then input the
respective ope codes. The respective commands are accepted at the 7-th clock rise. Even with input over 7 clocks,
command becomes valid.
When to carry out write command, it is necessary to set write enable status by the write enable command. If write
command is input in the write disable status, the command is cancelled. And even in the write enable status, once write
command is executed, it gets in the write disable status. After power on, this IC is in write disable status.
2. Read command (READ)
Product
number
Address
length
BR25S320-W
A11-A0
BR25S640-W
A12-A0
BR25S128-W
A13-A0
BR25S256-W
A14-A0
By read command, data of EEPROM can be read. As for this command, set CSB LOW, then input address after read ope
code. EEPROM starts data output of the designated address. Data output is started from SCK fall of 23-th clock, and
from D7 to D0 sequentially. This IC has increment read function. After output of data for 1 byte (8bits), by continuing input
of SCK, data of the next address can be read. Increment read can read all the addresses of EEPROM. After reading data
of the most significant address, by continuing increment read, data of the most insignificant address is read.
WREN (WRITE ENABLE): Write enable
Fig.33 Write enable command
High-Z
603 712 45
CSB
SCK
SO
SI
00000110
Fig.34 Write disable command
WRDI (WRITE DISABLE): Write disable
High-Z
0000
SI
0100
0312 4 7
CSB
SCK
5 6
SO
High-Z
11
1 1 0
0 3 7 1 2
D6
SO
CSB
SCK
SI
4 5
A12
6 8
* A0A1
D7
23 3024
D0
0 0 0 0 0
D2 D1
9
10
A13 A14
30
31
Fig.35 Read command