SCLK is the serial clock input that shifts data into and out of the ADC. The ADC latches DIN data on the rising edge of SCLK. DOUT data are shifted out on the falling edge of SCLK. Keep SCLK low when not active. The SCLK pin is a Schmidt-trigger input that reduces sensitivity to SCLK noise. However, keep the SCLK signal as noise free as possible to prevent inadvertent shifting of the data.