The FDC uses an extended start sequence with I²C for register access. The maximum speed of the I²C interface is 400 kbit/s. This sequence follows the standard I²C 7-bit target address followed by an 8-bit pointer register byte to set the register address. When the ADDR pin is set low, the FDC I²C address is 0x2A; when the ADDR pin is set high, the FDC I²C address is 0x2B. The ADDR pin must not change state after the FDC exits Shutdown Mode.

Figure 6-6 I²C Write Register Sequence

Figure 6-7 I²C Read Register Sequence