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ST72325J4B5

8-BIT MCU WITH 16 TO 60K FLASH/ROM, ADC, CSS, FIVE TIMERS, SPI, SCI, I2C INTERFACE

STMicroelectronics 

ST72325

COMMUNICATION INTERFACE CHARACTERISTICS (Cont’d)

12.11.2 I2C - Inter IC Control Interface

Subject to general operating conditions for VDD,

fCPU, and TA unless otherwise specified.

Refer to I/O port characteristics for more details on

the input/output alternate function characteristics

(SDAI and SCLI). The ST7 I2C interface meets the

requirements of the Standard I2C communication

protocol described in the following table.

Symbol

Parameter

Standard mode I2C

Min 1)

Max 1)

tw(SCLL) SCL clock low time

tw(SCLH) SCL clock high time

tsu(SDA) SDA setup time

th(SDA) SDA data hold time

tr(SDA)

tr(SCL)

SDA and SCL rise time

tf(SDA)

tf(SCL)

SDA and SCL fall time

th(STA) START condition hold time

tsu(STA) Repeated START condition setup time

tsu(STO) STOP condition setup time

tw(STO:STA) STOP to START condition time (bus free)

Cb

Capacitive load for each bus line

4.7

4.0

250

0 3)

1000

300

4.0

4.7

4.0

4.7

400

Figure 93. Typical Application with I2C Bus and Timing Diagram 4)

VDD

VDD

Fast mode I2C5)

Min 1)

Max 1)

1.3

0.6

100

0 2)

900 3)

20+0.1Cb 300

20+0.1Cb 300

0.6

0.6

0.6

1.3

400

Unit

µs

ns

µs

µs

µs

pF

I2C BUS

4.7kΩ

SDA

START

4.7kΩ

100Ω

100Ω

SDAI

SCLI

ST72XXX

tsu(STA)

REPEATED START

tw(STO:STA) START

tf(SDA)

tr(SDA)

tsu(SDA) th(SDA)

STOP

SCK

th(STA) tw(SCKH) tw(SCKL)

tr(SCK)

tf(SCK)

tsu(STO)

Notes:

1. Data based on standard I2C protocol requirement, not tested in production.

2. The device must internally provide a hold time of at least 300ns for the SDA signal in order to bridge the undefined

region of the falling edge of SCL.

3. The maximum hold time of the START condition has only to be met if the interface does not stretch the low period of

SCL signal.

4. Measurement points are done at CMOS levels: 0.3xVDD and 0.7xVDD.

5. At 4MHz fCPU, max.I2C speed (400kHz) is not achievable. In this case, max. I2C speed will be approximately 260KHz.

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