Datasheet
DS10668 Rev 6 91/126
STM32L031x4/6 Electrical characteristics
96
6.3.19 Communications interfaces
I
2
C interface
characteristics
The
I
2
C interface meets the timings requirements of the
I
2
C-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
I
2
C timing requirements are guaranteed by design when the
I
2
C peripheral is properly
configured (refer to the reference manual for details). 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
I
2
C SDA and SCL I/Os embed an analog filter (see Table 65 for the analog filter
characteristics).
The analog spike filter is compliant with
I
2
C timings requirements only for the following
voltage ranges:
• Fast mode Plus: 2.7 V ≤
V
DD
≤ 3.6 V and voltage scaling Range 1
• Fast mode:
–2V ≤ V
DD
≤ 3.6 V and voltage scaling Range 1 or Range 2.
–V
DD
< 2 V, voltage scaling Range 1 or Range 2, C
load
< 200 pF.
In other ranges, the analog filter must be disabled. The digital filter can be used instead.
Note: In Standard mode, no spike filter is required.
t
COUNTER
16-bit counter clock
period when internal clock
is selected (timer’s
prescaler disabled)
- 1 65536 t
TIMxCLK
f
TIMxCLK
= 32 MHz 0.0312 2048 µs
t
MAX_COUNT
Maximum possible count
- - 65536 × 65536 t
TIMxCLK
f
TIMxCLK
= 32 MHz - 134.2 s
1. TIMx is used as a general term to refer to the TIM2, TIM21, and TIM22 timers.
Table 64. TIMx
(1)
characteristics (continued)
Symbol Parameter Conditions Min Max Unit
Table 65. I2C analog filter characteristics
(1)
1. Guaranteed by characterization results.
Symbol Parameter Conditions Min Max Unit
t
AF
Maximum pulse width of spikes that
are suppressed by the analog filter
Range 1
50
(2)
2. Spikes with widths below t
AF(min)
are filtered.
100
(3)
nsRange 2 -
Range 3 -
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