BU9883FV-W Datasheet, PDF (14/19 Pages) Rohm – I2C BUS 3Ports for HDMI Port Serial EEPROM

●Command cancel by start condition and stop condition
During command input, by continuously inputting start condition and stop condition, command can be cancelled.
(Refer to Fig. 52.)
However, in ACK output area and during data read, SDA0～3 bus may output 'L', and in this case, start condition and stop
condition cannot be input, so reset is not available. Therefore, execute software reset. And when command is cancelled by
start, stop condition, during random read cycle, sequential read cycle, or current read cycle, internal setting address is not
determined, therefore, it is not possible to carry out current read cycle in succession. When to carry out read cycle in
succession, carry out random read cycle.
SCL0～3
SDA0～3
1
0
1
0
Start condition Stop condition
Fig.52 Case of cancel by start, stop condition during slave address input
●I/O peripheral circuit
○Pull up resistance of SDA0～3 terminal
SDA0～3 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_OL0～3-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. The following Vcc, SDA, R_PU and I_L correspond to them of each port.
(1)SDA0～3 rise time to be determined by the capacitance (CBUS) of bus line of R_PU and SDA0～3 should be tR or below.
And AC timing should be satisfied even when SDA0～3 rise time is late.
(2)The bus electric potential A to be determined by input leak total (I_L) of device connected to bus at output of 'H' to SDA0～3 bus and
R_PU should sufficiently secure the input 'H' level (V_IH) of microcontroller and EEPROM including recommended noise margin 0.2Vcc.
Vcc - I_LR_PU － 0.2Vcc ≧ V_IH
∴ R_PU ＝
0.8Vcc－V_IH
I_L
Ex. ) When V_CC =3V, I_L=10μA, V_IH=0.7 V_CC,
from (2)
0.8×3－0.7×3
R_PU ≦
10×10^-6
≦ 300 [kΩ]
Microcマonイtroコllerン
IL
R_PU
A
BU9883FV-W
SDA terminal
IL
Bus line
バス_caラ_pイ_acン_ity容量
C^CB^BU^US^S
○Minimum value of R_PU
Fig.53 I/O circuit diagram
The minimum value of R_PU is determined by the following factors. The following Vcc, V_OL, I_OL, and R_PU correspond to them of each port.
(1)When IC outputs LOW, it should be satisfied that V_OLMAX=0.4V and I_OLMAX=3mA.
V_CC－V_OL
R_PU
≦ I_OL
V_C－V_OL
∴ R_PU ≦
I_OL
(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 V_CC
Ex. ) When V_CC =3V, V_OL=0.4V, I_OL=3mA, microcontroller, EEPROM V_IL=0.3Vcc
from (1)
R_PU ≧
3－0.4
3×10 ^-3
≧ 867 [Ω]
And
V_OL = 0.4 [V]
V_IL = 0.3×3
= 0.9 [V]
Therefore, the condition (2) is satisfied.
○Pull up resistance of SCL0～3 terminal
When SCL0～3 control is made at CMOS output port, there is no need, but in the case there is timing where SCL0～3 becomes 'Hi-Z', add a
pull up resistance. As for the pull up resistance, one of several kΩ ~ several ten kΩ is recommended in consideration of drive performance
of output port of microcontroller.
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