8.4.4 ADC Clock Mode

Operate the ADC with an external clock or with the internal oscillator. The clock frequency is 7.3728 MHz. For external clock operation, apply the clock signal to CLKIN. For internal-clock operation, connect CLKIN to DGND. The internal oscillator begins operation immediately at power-up. The ADC automatically selects the clock mode of operation. Read the clock mode bit in the STATUS register to determine the clock mode.