Datasheet

STM32F405xx, STM32F407xx Electrical characteristics
Doc ID 022152 Rev 2 107/167
Figure 36. 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 51. SCL frequency (f
PCLK1
= 42 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 0x8019
300 0x8021
200 0x8032
100 0x0096
50 0x012C
20 0x02EE
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