BU9844GUL-W_13 Datasheet, PDF (18/30 Pages) Rohm – WLCSP EEPROM

BU9844GUL-W (16Kbit)
Datasheet
I/O peripheral circuit
1. 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.
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 capacity (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 at 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.
VCC - ILRPU - 0.2VCC ≥VIH
∴RPU
≤ ^0.8VCC
IL
-VIH
Ex.) When V_CC =3V, I_L=10μA, V_IH=0.7 Vcc
from (2)
0.8 ×3 -0.7 ×3
∴RPU ≤ _{10 ×10 -6}
≤ 300 kΩ
Microcontroller
IL
RPU
A
EEPROM
SDA terminal
IL
Bus line
capacity CBUS
Figure 44. I/O circuit diagram
3. 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 VOLMAX = 0.4V and IOLMAX = 3mA.
VCC -VOL
RPU ^≤IOL
∴RPU
≥^{VCC -VOL}
IOL
(2) VOLMAX = 0.4V should secure the input “L” level (VIL) of microcontroller and EEPROM including recommended noise
margin 0.1V_CC.
VOLMAX ≤VIL ‐ 0.1VCC
Ex.) When V_CC = 3V, V_OL = 0.4V, I_OL = 3mA, microcontroller, EEPROM V_IL = 0.3V_CC
From (1),
3 -0.4
∴RPU
≥
3 ×10
-3
≥867 [Ω ]
And VOL = 0.4 [V ]
VIL = 0.3 × 3
= 0.9 [V ]
Therefore, the condition (2) is satisfied.
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TSZ02201-0R2R0G100470-1-2
17.Sep.2013 Rev.002