ST92F124/F150/F250 - ELECTRICAL CHARACTERISTICS
I2C/DDC-BUS TIMING TABLE (Cont’d)
The following table gives the values to be written in
the I2CCCR and I2CECCR registers to obtain the
required I2C SCL line frequency.
Table 70. SCL Frequency Table
fSCL
(kHz)
400
300
200
100
50
I2CCCR Value
fCPU=12 MHz
fCPU=24 MHz.
VDD = 5 V
RP=3.3kΩ
RP=4.7kΩ
RP=3.3kΩ
RP=4.7kΩ
I2CECCR I2CCCR I2CECCR I2CCCR I2CECCR I2CCCR I2CECCR I2CCCR
0
86h
0
85h
0
8Fh
0
8Eh
0
89h
0
89h
0
95h
0
94h
0
90h
0
8Fh
0
A2h
0
A2h
0
36h
0
36h
0
71h
0
70h
0
72h
0
72h
0
64h
1
64h
Legend:
RP = External pull-up resistance
fSCL = I2C speed
NA = Not achievable
Note:
– For speeds around 200 kHz, achieved speed can have ±5% tolerance
– For other speed ranges, achieved speed can have ±2% tolerance
The above variations depend on the accuracy of the external components used.
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