The AD7923 is a 12-bit， high speed， low power， 4-channel， successive approximation （SAR） ADC. It operates from a single 2.7 V to 5.25 V power supply and features throughput rates up to 200 kSPS. It contains a low noise， wide bandwidth track-and-hold amplifier that can handle input frequencies in excess of 8 MHz. The conversion process and data acquisition are controlled by CS and the serial clock， allowing the device to easily interface with microprocessors or DSPs. The input signal is sampled on the falling edge of CS; the conversion is also initiated at this point. The AD7923 uses advanced design techniques to achieve very low power dissipation at maximum throughput rates. At maximum throughput rates， it consumes 1.2 mA maximum with 3 V supplies and 1.5 mA maximum with 5 V supplies. Through the configuration of the control register， the analog input range can be selected as 0 V to REFIN or 0 V to 2 × REFIN， with either straight binary or twos complement output coding. The AD7923 features four single-ended analog inputs with a channel sequencer to allow a preprogrammed selection of channels to be converted sequentially. The conversion time for the AD7923 is determined by the serial clock， SCLK， frequency， since this is used as the master clock to control the conversion. The conversion time can be as short as 800 ns with a 20 MHz SCLK.