In 2 Wire mode, all 14 bits of one channel are being transmitted on two wires, 7 bits per wire. In a 2CH ADC (ADC3643), there are a total of 6 data outputs/resistors: 4 data resistors (2 per channel), 1 Data Clock and 1 Frame Clock.

Figure 2-5 ADC3643 Serial CMOS: 2 Wire Resistors

A total of 7 bits per wire will be transmitted over one frame clock period. The serialization rate is 7x times the sampling rate. The data rate is limited to ~250 due to the CMOS interface, so the max sampling rate in this mode is 35 MSPS. Higher sampling rates can be used when decimation is used.

Figure 2-6 Serial CMOS 2W Timing Diagram