BU9891GUL-W_12 Datasheet, PDF (12/26 Pages) Rohm – WLCSP EEPROM

BU9891GUL-W (4Kbit)
Datasheet
●Description of operations
Communications of the Microwire Bus are carried out by SK (serial clock), DI (serial data input),DO (serial data output) ,and
CS (chip select) for device selection.
When to connect one EEPROM to a microcontroller, connect it as shown in Figure 30(a) or Figure 30(b). When to use the
input and output common I/O port of the microcontroller, connect DI and DO via a resistor as shown in Figure 30(b), and
connection by 3 lines is available.
In the case of plural connections, refer to Figure 30(c).
Micro-
controller
CS
SK
DO
BU9891GUL-W
CS
Micro-
controller
CS
SK
SK
DI
DO
BU9891GUL-W
CS
SK
DI
Micro-
controller
CS2
CS1
CS0
SK
DO
DI
DI
DO
DO
Device 1
Device 2
Device 3
Figure 30-(a) Connection by 4 lines Figure 30-(b) Connection by 3 lines Figure 30-(c) Connection example of plural devices
Figure 30. Connection method with microcontroller
Communications of the Microwire Bus are started by the first “1” input after the rise of CS. This input is called a start bit.
After input of the start bit, inputs ope code, address and data. Address and data are input all in MSB first manners.
“0” input after the rise of CS to the start bit input is all ignored. Therefore, when there is limitation in the bit width of PIO of
the microcontroller, input “0” before the start bit input, to control the bit width.
●Command mode
Command
Read (READ)
*1
Start bit
1
Ope code
Address
10
A7,A6,A5,A4,A3,A2,A1,A0
Data
D15 to D0(READ DATA)
Write enable (WEN)
1
Write (WRITE)
*2
1
00
11******
01
A7,A6,A5,A4,A3,A2,A1,A0 D15 to D0(WRITE DATA)
Write disable (WDS)
1
00
・ Input the address and the data in MSB first manners.
・ As for *, input either VIH or VIL.
00******
*Start bit
Acceptance of all the commands of this IC starts at recognition of the start bit.
The start bit means the first “1” input after the rise of CS.
*1 As for read, by continuous SK clock input after setting the read command, data output of the set address starts, and
address data in significant order are sequentially output continuously. (Auto increment function)
*2 When the read and the write all commands are executed, data written in the selected memory cell is automatically deleted, and input data is written.
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TSZ22111・15・001
12/22
TSZ02201-0R2R0G100440-1-2
3.SEP.2012 Rev.001