BU9889GUL-W_12 Datasheet, PDF (18/27 Pages) Rohm – WLCSP EEPROM

BU9889GUL-W (8Kbit)
Datasheet
●I/O peripheral circuit
○Pull up resistance of SDA terminal
SDA is NMOS open drain, so requires pull up resistance. As for this resistance value (R_PU), select an appropriate value to
this resistance value from microcontroller V_IL, I_L, and V_OL-I_OL characteristics of this IC. If R_PU is large, action frequency is
limited. The smaller the R_PU, the larger the consumption current at action.
○Maximum value of R_PU
The maximum value of R_PU is determined by the following factors.
(1)SDA rise time to be determined by the capacitance (CBUS) of bus line of R_PU and SDA should be tR or below.
And AC timing should be satisfied even when SDA rise time is late.
(2)The bus electric potential ○^A to be determined by input leak total (I_L) of device connected to bus output of 'H' to SDA
bus and R_PU should sufficiently secure the input 'H' level (V_IH) of microcontroller and EEPROM including recommended
noise margin 0.2Vcc.
Microcontroller
BU9889GUL-W
Vcc - I_LR_PU - 0.2Vcc ≧ V_IH
∴
RPU
≦
0.8VCC－VIH
I_L
Ex.) When Vcc = 3V, I_L=10μA, V_IH = 0.7Vcc, from (2)
RPU
≦
0.8×3－0.7×3
10×10^-6
≦ 300 ［kΩ］
R_PU
A
SDA terminal
IL
IL
Bus line
Capacity
CBUS
Figure 41. I/O circuit diagram
○Minimum value of R_PU
The minimum value of R_PU is determined by the following factors.
(1)When IC outputs LOW, it should be satisfied that V_OLMAX=0.4V and I_OLMAX=3mA.
VCC－VOL
RPU
≦
IOL
∴
RPU
≧
VCC－VOL
IOL
(2)V_OLMAX=0.4V should secure the input 'L' level (V_IL) of microcontroller and EEPROM including recommended noise
margin 0.1Vcc.
V_OLMAX ≦ V_IL-0.1 Vcc
Ex.) When Vcc= 3V, V_OL0.4V, I_OL=3mA, microcontroller, EEPROM V_IL=0.3Vcc
from(1),
R_PU
≧
3－0.4
3×10 ^-3
≧ 867 ［Ω］
And
V_OL=0.4ï¼»Vï¼½
V_IL=0.3×3
=0.9ï¼»Vï¼½
Therefore, the condition (2) is satisfied.
○Pull up resistance of SCL terminal
When SCL control is made at CMOS output port, there is no need, but in the case there is timing where SCL becomes
'Hi-Z', add a pull up resistance. As for the pull up resistance, one of several kΩ to several ten kΩ is recommended in
consideration of drive performance of output port of microcontroller.
●A2, WP process
○Process of device address terminals (A2)
Check whether the set device address coincides with device address input sent from the master side or not, and select
one among plural devices connected to a same bus. Connect this terminal to pull up or pull down, or Vcc or GND.
○Process of WP terminal
WP terminal is the terminal that prohibits and permits write in hardware manner. In 'H' status, only READ is available and
WRITE of all address is prohibited. In the case of 'L', both are available. In the case of use it as an ROM, it is
recommended to connect it to pull up or Vcc. In the case to use both READ and WRITE, control WP terminal or connect it
to pull down or GND.
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TSZ22111・15・001
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TSZ02201-0R2R0G100490-1-2
05.SEP.2012 Rev.001