Datasheet

Electrical characteristics STM32F401xB STM32F401xC
96/139 DS9716 Rev 11
6.3.19 Communications interfaces
I
2
C interface characteristics
The I2C interface meets the requirements of the standard I
2
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
DD is
disabled, but is still present.
The I
2
C 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 I
2
C bus interface supports standard mode (up to 100 kHz) and fast mode (up to 400
kHz). The I
2C 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. I
2
C characteristics
Symbol Parameter
Standard mode I
2
C
(1)
Fast mode I
2
C
(1)(2)
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)
t
r(SDA)
t
r(SCL)
SDA and SCL rise time - 1000 - 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 - µs
t
w(STO:STA)
Stop to Start condition time (bus free) 4.7 - 1.3 - µs
t
SP
Pulse width of the spikes that are
suppressed by the analog filter for
standard fast mode
050
(4)
050
(4)
ns
C
b
Capacitive load for each bus line - 400 - 400 pF
1.
Guaranteed by design.
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
I
2
C frequencies, and a multiple of 10 MHz to reach the 400 kHz maximum I
2
C fast mode clock.
3. The maximum data hold time has only to be met if the interface does not stretch the low period of SCL signal.
4. The minimum width of the spikes filtered by the analog filter is above t
SP
(max).
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