BR24G64NUX-5(2017) 查看數據表（PDF） - ROHM Semiconductor

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BR24G64NUX-5
(Rev.:2017)

Serial EEPROM Series Standard EEPROM I2C BUS EEPROM (2-Wire)

ROHM Semiconductor 

BR24G64xxx-5 Series

Application Examples

1. I/O Peripheral Circuit

(1) Pull-up Resistance of SDA Pin

SDA is NMOS open drain, so it requires a pull-up resistor. As for this resistor value (RPU), select an appropriate value

from microcontroller VIL, IL, and VOL-IOL characteristics of this IC. If RPU is large, operating frequency is limited. The

smaller the RPU increases the supply current.

(2) Maximum Value of RPU

The maximum value of RPU is determined by the following factors.

(a) SDA rise time determined by the capacitance (CBUS) of bus line of SDA and RPU should be tR or lower.

Furthermore, AC timing should be satisfied even when SDA rise time is slow.

○ (b) The bus electric potential A to be determined by input current leak total (IL) of the device connected to bus at

output of 'HIGH' to SDA line and RPU should sufficiently secure the input 'HIGH' level (VIH) of microcontroller and

EEPROM including recommended noise margin of 0.2VCC.

VCC -ILRPU -0.2VCC VIH

Microcontroller

VCC

EEPROM

∴RPU



0.8VCC

IL

-VIH

Ex.) VCC=3V IL=10µA VIH=0.7VCC

from (b)

∴RPU



0.8 3 -0.7 3

10 10 -6

 30 [ kΩ ]

IL

RPU

A

SDA Pin

IL1

IL2

Bus line

Capacitance

CBUS

Figure 51. I/O Circuit Diagram

(3) Minimum Value of RPU

The minimum value of RPU is determined by the following factors.

○ (a) When IC outputs 'LOW', the bus electric potential A should be equal to or less than output 'LOW' level (VOL)

of EEPROM.

VCC -VOL

RPU



IOL

∴RPU VCC -VOL

IOL

Ex.) VCC=3V, VOL=0.4V, IOL=3.2mA, microcontroller, EEPROM VIL=0.3VCC

∴RPU



3

3.2

-0.4

10 -3

812　 .5 [ Ω ]

(4) Pull-up Resistance of SCL Pin

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, decide with the balance with drive

performance of output port of microcontroller.

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TSZ02201-0GGG0G100910-1-2

30.Nov.2017 Rev.001

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