STM32L021D4 datasheet(87/114 Pages) STMICROELECTRONICS

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STM32L021x4

Electrical characteristics

6.3.19

Communications interfaces

I2C interface characteristics

The I2C interface meets the timings requirements of the I2C-bus specification and user

manual rev. 03 for:

•

Standard-mode (Sm) : with a bit rate up to 100 kbit/s

•

Fast-mode (Fm) : with a bit rate up to 400 kbit/s

•

Fast-mode Plus (Fm+) : with a bit rate up to 1 Mbit/s.

The I2C timing requirements are guaranteed by design when the I2C peripheral is properly

configured (refer to the reference manual for details) and when the I2CCLK frequency is

greater than the minimum given in Table 62. The SDA and SCL I/O requirements are met

with the following restrictions: the SDA and SCL I/O pins are not "true" open-drain. When

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

disabled, but is still present. Only FTf I/O pins support Fm+ low level output current

maximum requirement (refer to Section 6.3.13: I/O port characteristics for the I2C I/Os

characteristics).

All I2C SDA and SCL I/Os embed an analog filter (see Table 61 for the analog filter

characteristics).

The analog spike filter is compliant with I2C timings requirements only for the following

voltage ranges:

•

Fast mode Plus: 2.7 V

≤VDD ≤3.6 V and voltage scaling Range 1

•

Fast mode:

–2 V

≤VDD ≤3.6 V and voltage scaling Range 1 or Range 2.

–VDD < 2 V, voltage scaling Range 1 or Range 2, Cload < 200 pF.

In other ranges, the analog filter should be disabled. The digital filter can be used instead.

Note:

In Standard mode, no spike filter is required.

Table 61. I2C analog filter characteristics(1)

1. Guaranteed by characterization results.

Symbol

Parameter

Conditions

Min

Max

Unit

tAF

Maximum pulse width of spikes that

are suppressed by the analog filter

Range 1

50(2)

2. Spikes with widths below tAF(min) are filtered.

260(3)

3. Spikes with widths above tAF(max) are not filtered

Range 2

Range 3

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