STR71XF datasheet(61/77 Pages) STMICROELECTRONICS

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STR71xF

Electrical parameters

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5.3.8

Communications interfaces

I2C - Inter IC Control Interface

Subject to general operating conditions for V33, fPCLK1, and TA unless otherwise specified.

The STR7 I2C interface meets the requirements of the Standard I2C communication

protocol described in the following table with the restriction mentioned below:

Note:

Restriction: The I/O pins which SDA and SCL are mapped to are not “True” Open-Drain:

when configured as open-drain, the PMOS connected between the I/O pin and V33 is

disabled, but it is still present. Also, there is a protection diode between the I/O pin and V33.

Consequently, when using this I2C in a multi-master network, it is not possible to power off

the STR7X while some another I2C master node remains powered on: otherwise, the

STR7X will be powered by the protection diode.

Refer to I/O port characteristics for more details on the input/output alternate function

characteristics (SDA and SCL).

Notes:

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

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.

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

Table 34.

I2C Characteristics

Symbol

Parameter

Standard mode

I2C

Fast mode I2C5)

Unit

Min 1)

Max 1)

Min 1)

Max 1)

tw(SCLL)

SCL clock low time

4.7

1.3

µs

tw(SCLH)

SCL clock high time

4.0

0.6

tsu(SDA)

SDA setup time

250

100

th(SDA)

SDA data hold time

0 3)

0 2)

900 3)

tr(SDA)

tr(SCL)

SDA and SCL rise time

1000

20+0.1C

300

tf(SDA)

tf(SCL)

SDA and SCL fall time

300

20+0.1C

300

th(STA)

START condition hold time

4.0

0.6

µs

tsu(STA)

Repeated START condition setup

time

4.7

0.6

tsu(STO)

STOP condition setup time

4.0

0.6

µs

tw(STO:STA)

STOP to START condition time (bus

free)

4.7

1.3

µs

Capacitive load for each bus line

400

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