Electrical characteristics
STM32F302xx/STM32F303xx
6.3.17
Communications interfaces
I2C interface characteristics
Unless otherwise specified, the parameters given in Table 59 are derived from tests
performed under ambient temperature, f
frequency and V supply voltage conditions
PCLK1
DD
summarized in Table 22.
2
2
The I C interface meets the requirements of the standard I C 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 V is
DD
disabled, but is still present.
2
The I C characteristics are described in Table 59. Refer also to Section 6.3.14: I/O port
for more details on the input/output alternate function characteristics (SDA
characteristics
and SCL)
.
2
(1)
Table 59. I C characteristics
Standard
mode
Fast mode
Fast Mode Plus
Symbol
Parameter
Unit
Min
Max
Min
Max
Min
Max
tw(SCLL)
tw(SCLH)
tsu(SDA)
th(SDA)
SCL clock low time
4.7
4.0
-
1.3
0.6
-
0.5
0.26
50
-
µs
SCL clock high time
SDA setup time
-
-
-
-
-
250
0(3)
-
100
0(3)
SDA data hold time
3450(2)
900(2)
0
450
tr(SDA)
tr(SCL)
ns
SDA and SCL rise time
SDA and SCL fall time
-
-
1000
300
300
300
120
120
-
-
-
-
tf(SDA)
tf(SCL)
th(STA)
tsu(STA)
tsu(STO)
Start condition hold time
4.0
4.7
4.0
4.7
-
-
0.6
0.6
0.6
1.3
-
-
0.26
0.26
0.26
0.5
-
-
µs
Repeated Start condition setup time
Stop condition setup time
-
-
-
-
-
-
-
-
-
μs
μs
pF
tw(STO:STA) Stop to Start condition time (bus free)
Cb Capacitive load for each bus line
400
400
550
The I2C characteristics are the requirements from I2C bus specification rev03. They are guaranteed by design when
I2Cx_TIMING register is correctly programmed (Refer to reference manual). These characteristics are not tested in
production.
1.
The maximum Data hold time has only to be met if the interface does not stretch the low period of SCL signal.
2.
3.
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.
(1)
Table 60. I2C analog filter characteristics
Symbol
Parameter
Min
Max
Unit
Pulse width of spikes that are
suppressed by the analog filter
tSP
50
260
ns
1. Guaranteed by design, not tested in production.
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