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Electrical characteristics

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6.3.19

Communications interfaces

I2C interface characteristics

The I2C interface meets the requirements of the standard I2C communication protocol with

the following restrictions: the I/O pins 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 VDD is

disabled, but is still present.

The I2C characteristics are described in Table59. Refer also to Section 6.3.16: I/O port

characteristics for more details on the input/output alternate function characteristics (SDA

and SCL).

The I2C bus interface supports standard mode (up to 100 kHz) and fast mode (up to 400

kHz). The I2C bus frequency can be increased up to 1 MHz. For more details about the

complete solution, please contact your local ST sales representative.

Table 59. I2C characteristics

Symbol

Parameter

Standard mode I2C(1)

1. Guaranteed by design, not tested in production.

Fast mode I2C(1)(2)

2. fPCLK1 must be at least 2 MHz to achieve standard mode I2C frequencies. It must be at least 4 MHz to

achieve fast mode I2C frequencies, and a multiple of 10 MHz to reach the 400 kHz maximum I2C fast mode

clock.

Unit

Min

Max

Min

Max

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

900(3)

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

signal.

tr(SDA)

tr(SCL)

SDA and SCL rise time

1000

300

tf(SDA)

tf(SCL)

SDA and SCL fall time

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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