Datasheet

Electrical characteristics STM32F103x8, STM32F103xB
58/84
Figure 24. I
2
C bus AC waveforms and measurement circuit
1.
Measurement points are done at CMOS levels: 0.3V
DD
and 0.7V
DD
.
Table 39. SCL frequency (f
PCLK1
= 36 MHz.,V
DD
= 3.3 V)
(1)(2)
1. R
P
= External pull-up resistance, f
SCL
= I
2
C speed,
2. For speeds around 200 kHz, the tolerance on the achieved speed is of ±5%. For other speed ranges, the
tolerance on the achieved speed ±2%. These variations depend on the accuracy of the external
components used to design the application.
f
SCL
(kHz)
I2C_CCR value
R
P
= 4.7 kΩ
400 0x801E
300 0x8028
200 0x803C
100 0x00B4
50 0x0168
20 0x0384
ai14149b
START
SD A
100Ω
4.7kΩ
I
2
C bus
4.7kΩ
100Ω
V
DD
V
DD
STM32F103xx
SDA
SCL
t
f(SDA)
t
r(SDA)
SCL
t
h(STA)
t
w(SCKH)
t
w(SCKL)
t
su(SDA)
t
r(SCK)
t
f(SCK)
t
h(SDA)
S TART REPEATED
START
t
su(STA)
t
su(STO)
S TOP
t
su(STA:STO)