BRCA016GWZ-W_13 Datasheet, PDF (17/25 Pages) Rohm – Serial EEPROM Series Standard EEPROM WLCSP EEPROM

BRCA016GWZ-W (16Kbit)
Datasheet
I/O Peripheral Circuit
1. Pull Up Resistance of SDA terminal
SDA is NMOS open drain, so it requires a pull up resistor. As for this resistance value (R_PU), select an appropriate value
from microcontroller V_IL, I_L, and V_OL-I_OL characteristics of this IC. If R_PU is large, operating frequency is limited. The smaller
the R_PU, the larger is the supply current (Read).
2. 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 (C_BUS) of bus line of R_PU and SDA should be t_R or lower.
Furthermore, AC timing should be satisfied even when SDA rise time is slow.
(2)The bus’ electric potential A to be determined by the input current leak total (I_L) of the device connected to the
bus with output of 'H' to the SDA line and R_PU should sufficiently secure the input 'H' level (V_IH) of microcontroller and
EEPROM including recommended noise margin of 0.2Vcc.
V_CC - I_LR_PU － 0.2Vcc ≧ V_IH
0.8Vcc－V_IH
∴ R_PU ≦
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]
Microcontroller
IL
R_PU
A
BRCA016GWZ-W
SDA Terminal
IL
Bus Line
Capacity
C_BUS
3. Minimum Value of R_PU
Figure 37. I/O Circuit Diagram
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.
V_CC－V_OL
R_PU
≦ I_OL
V_CC－V_OL
∴ R_PU ≧
I_OL
(2)V_OLMAX=0.4V should secure the input 'L' level (V_IL) of microcontroller and EEPROM including the recommended noise
margin 0.1 of Vcc.
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)
And
R_PU ≧
3－0.4
3×10 ^-3
≧ 867 [Ω]
V_OL = 0.4 [V]
V_IL = 0.3×3
= 0.9 [V]
Therefore, the condition (2) is satisfied.
4. Pull-up Resistance of SCL Terminal
When SCL control is made at the CMOS output port, there is no need for a pull up resistor. But when there is a time
where SCL becomes 'Hi-Z', add a pull up resistor. As for the pull up resistor value, one of several kΩ to several ten kΩ
is recommended in consideration of drive performance of output port of microcontroller.
5. 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 case of 'L', both are available. If using as an ROM, it is recommended to connect it
to pull up or Vcc. If using both READ and WRITE, control WP terminal or connect it to pull down or GND.
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25.Feb.2013 Rev.002