Electrical characteristics
STM32L151x6/8/B, STM32L152x6/8/B
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DocID17659 Rev 10
6.3.16 Communication
interfaces
I
2
C interface characteristics
The STM32L15xx6/8/B product line I
2
C interface meets the requirements of the standard
I
2
C communication protocol with the following restrictions: SDA and SCL are not “true”
open-drain I/O pins. When configured as open-drain, the PMOS connected between the I/O
pin and V
DD
is disabled, but is still present.
The I
2
C characteristics are described in
. Refer also to
for more details on the input/output alternate function characteristics
(SDA and SCL).
Table 47. I
2
C characteristics
Symbol
Parameter
Standard mode I
2
C
(1)
1. Guaranteed by design, not tested in production.
Fast mode I
2
2. f
PCLK1
must be at least 2 MHz to achieve standard mode I
²
C frequencies. It must be at least 4 MHz to
achieve fast mode I²C frequencies. It must be a multiple of 10 MHz to reach the 400 kHz maximum I²C fast
mode clock.
Unit
Min
Max
Min
Max
t
w(SCLL)
SCL clock low time
4.7
-
1.3
-
µs
t
w(SCLH)
SCL clock high time
4.0
-
0.6
-
t
su(SDA)
SDA setup time
250
-
100
-
ns
t
h(SDA)
SDA data hold time
0
-
0
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.
t
r(SDA)
t
r(SCL)
SDA and SCL rise time
-
1000
20 + 0.1C
b
300
t
f(SDA)
t
f(SCL)
SDA and SCL fall time
-
300
-
300
t
h(STA)
Start condition hold time
4.0
-
0.6
-
µs
t
su(STA)
Repeated Start condition
setup time
4.7
-
0.6 -
t
su(STO)
Stop condition setup time
4.0
-
0.6
-
μ
s
t
w(STO:STA)
Stop to Start condition time
(bus free)
4.7
-
1.3
-
μ
s
C
b
Capacitive load for each bus
line
-
400
-
400
pF