BR24L02NUX-WTR Rohm Semiconductor, BR24L02NUX-WTR Datasheet - Page 17

• Manufacturer Part Number: BR24L02NUX-WTR
• Description: IC EEPROM 2KBIT 100KHZ VSON8
• Manufacturer: Rohm Semiconductor
• Series: -r

Specifications of BR24L02NUX-WTR

• Format - Memory: EEPROMs - Serial
• Memory Type: EEPROM
• Memory Size: 2K (256 x 8)
• Speed: 400kHz
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 1.8 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 8-UFDFN Exposed Pad
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

●Cautions on microcontroller connection
© 2009 ROHM Co., Ltd. All rights reserved.
BR24L□□-W Series,BR24S□□□-W Series
www.rohm.com
○Rs
○Maximum value of Rs
○Minimum value of Rs
In I
tri state to SDA port, insert a series resistance Rs between the pull up resistance Rpu and the SDA terminal of EEPROM.
This is controls over current that occurs when PMOS of the microcontroller and NMOS of EEPROM are turned ON
simultaneously. Rs also plays the role of protection of SDA terminal against surge. Therefore, even when SDA port is
open drain input/output, Rs can be used.
The maximum value of Rs is determined by the following relations.
(1)SDA rise time to be determined by the capacity (CBUS) of bus line of Rpu and SDA should be tR or below.
(2)The bus electric potential
The minimum value of Rs is determined by over current at bus collision. When over current flows, noises in power source
line, and instantaneous power failure of power source may occur. When allowable over current is defined as I, the
following relation must be satisfied. Determine the allowable current in consideration of impedance of power source line
in set and so forth. Set the over current to EEPROM 10mA or below.
2
And AC timing should be satisfied even when SDA rise time is late.
should sufficiently secure the input 'L' level (V
C BUS, it is recommended that SDA port is of open drain input/output. However, when to use CMOS input / output of
V
Fig.53 I/O circuit diagram
Microcontroller
IL
'H' output
Microcontroller
Microcontroller
Fig.55 I/O circuit diagram
R
Fig.56 I/O circuit diagram
V
PU
CC
R
Bus line
capacity CBUS
R
Over currentⅠ
S
PU
R
I
OL
R
EEPROM
S
○
PU
A to be determined by Rpu and Rs the moment when EEPROM outputs 'L' to SDA bus
A
R
S
EEPROM
EEPROM
'L' output
V
OL
IL
) of microcontroller including recommended noise margin 0.1Vcc.
17/40
'H' output of microcontroller
∴
Example)When V
Example) When V
SDA
SCL
from(2),
V
R
R
CC
S
S
∴
(V
≦
≧
CC
R
R
R
－V
V
S
S
PU
R
CC
CC
I
I
S
CC
OL
+R
Fig.54 Input / output collision timing
=3V, I=10mA
≦
≦
≦
Over current flows to SDA line by 'H'
output of microcontroller and 'L'
output of EEPROM.
=3V, VIL=0.3V
)×R
S
≧
≧
S
0.3×3－0.4－0.1×3
V
1.67［kΩ］
IL
1.1×3－0.3×3
10×10
－V
1.1V
300［Ω］
+
3
'L' output of EEPROM
OL
ACK
CC
-3
－0.1V
CC
－V
, V
IL
V
OL
CC
OL
=0.4V, R
Technical Note
2009.09 - Rev.D
+0.1V
×
×
CC
PU
≦V
R
=20kΩ
20×10
PU
IL
3