CD00253742 Datasheet, PDF (92/120 Pages) STMicroelectronics – XL-density performance line ARM-based 32-bit MCU

Electrical characteristics
STM32F103xF, STM32F103xG
Figure 46. I²C bus AC waveforms and measurement circuit
VDD
VDD
I²C bus
4 .7 k
4 .7 k
STM32F103xx
100
SDA
100
SCL
SD A
tf(SDA)
S TART
S TART REPEATED
tsu(STA)
S TART
tr(SDA)
tsu(SDA)
th(STA)
tw(SCLL)
th(SDA)
S TOP
tw(STO:STA)
SCL
tw(SCLH)
tr(SCL)
tf(SCL)
1. Measurement points are done at CMOS levels: 0.3V_DD and 0.7V_DD.
tsu(STO)
ai14149c
Table 55.
SCL frequency (f_PCLK1= 36 MHz.,V_DD = 3.3 V)⁽¹⁾⁽²⁾
f_SCL (kHz)
I2C_CCR value
R_P = 4.7 kΩ
400
0x801E
300
0x8028
200
0x803C
100
0x00B4
50
0x0168
20
0x0384
1. R_P = External pull-up resistance, f_SCL = I²C 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.
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Doc ID 16554 Rev 3