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BU9891GUL-W_12 Datasheet, PDF (17/26 Pages) Rohm – WLCSP EEPROM | |||
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BU9891GUL-W (4Kbit)
Datasheet
6) When to directly connect DI and DO
This IC has independent input terminal DI and output terminal DO, and separate signals are handled on timing chart,
meanwhile, by inserting a resistance R between these DI and DO terminals, it is possible to carry out control by 1 control
line.
Microcontroller
EEPROM
DI/O PORT
DI
R
DO
Figure 47. DI, DO control line common connection
âData collision of microcontroller DI/O output and DO output and feedback of DO output to DI input.
Drive from the microcontroller DI/O output to DI input on I/O timing, and signal output from DO output occur at the
same time in the following points.
(1) 1 clock cycle to take in A0 address data at read command
Dummy bit â0â is output to DO terminal.
âWhen address data A0 = â1â input, through current route occurs.
EEPROM CS input
âHâ
EEPROM SK input
EEPROM DI input
EEPROM DO output
A1 A0
Collision of DI input and DO output
High-Z
0 D15 D14 D13
Microcontroller DI/O port
A1 A0
High-Z
Microcontroller output Microcontroller input
Figure 48. Collision timing at read data output at DI, DO direct connection
(2) Timing of CS = âHâ after write command. DO terminal in READY / BUSY function output.
When the next start bit input is recognized, âHIGH-Zâ gets in.
âEspecially, at command input after write, when CS input is started with microcontroller DI/O output âLâ,
READY output âHâ is output from DO terminal, and through current route occurs.
Feedback input at timing of these (1) and (2) does not cause disorder in basic operations, if resistance R is inserted.
ï½ï½
EEPROM CS input
Write command
ï½ï½
ï½ï½
EEPROM SK input
Write command
ï½ï½
ï½ï½
EEPROM DI input
Write command
ï½ï½
EEPROM DO output
Write command
BUï½Sï½ Y
READY
ï½ï½
READY
High-Z
Collision of DI input and DO output
Microcontroller DI/O port
Write command
BUSY
ï½ï½
READY
ï½ï½
Microcontroller output
Microcontroller input
Microcontroller output
Figure 49. Collision timing at DI, DO direct connection
Note) As for the case (2), attention must be paid to the following.
When status READY is output, DO and DI are shared, DI=âHâ and the microcontroller DI/O=âHigh-Zâ or the microcontroller DI/O=âHâ,if SK clock is
input, DO output is input to DI and is recognized as a start bit, and malfunction may occur. As a method to avoid malfunction, at status READY
output, set SK=âLâ, or start CS within 4 clocks after âHâ of READY signal is output.
CS
Start bit
SK
DI
READY
DO
Because DI=âHâ, set
SK=âLâ at CS rise.
High-Z
Figure 50. Start bit input timing at DI, DO direct connection
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TSZ22111ã»15ã»001
17/22
TSZ02201-0R2R0G100440-1-2
3.SEP.2012 Rev.001
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