The AD7440/AD7450A1 are 10-bit and 12-bit high speed， low power， successive approximation （SAR） analog-to-digital converters with a fully differential analog input. These parts operate from a single 3 V or 5 V power supply and use advanced design techniques to achieve very low power dissipation at throughput rates up to 1 MSPS. The SAR architecture of these parts ensures that there are no pipeline delays. The parts contain a low noise， wide bandwidth， differential track-and-hold amplifier （T/H） that can handle input frequencies up to 3.5 MHz. The reference voltage is applied externally to the VREF pin and can be varied from 100 mV to 3.5 V depending on the power supply and what suits the application. The value of the reference voltage determines the common-mode voltage range of the part. With this truly differential input structure and variable reference input， the user can select a variety of input ranges and bias points. The conversion process and data acquisition are controlled using CS and the serial clock， allowing the device to interface with microprocessors or DSPs. The input signals are sampled 1 Protected by U.S. Patent Number 6，681，332.