The AD4021 is a high accuracy, high speed, low power, 20-bit, Easy Drive, precision successive approximation register (SAR) analog-to-digital (ADC) that operates from a single power supply, VDD. The reference voltage, VREF, is applied externally and can be set independent of the supply voltage. The AD4021 power scales linearly with throughput.Easy Drive features reduce both signal chain complexity and power consumption while enabling higher channel density. The reduced input current, particularly in high-Z mode, coupled with a long signal acquisition phase, eliminates the need for a dedicated ADC driver. Easy Drive broadens the range of companion circuitry that is capable of driving these ADCs (see Figure 2 in the data sheet).Input span compression eliminates the need to provide a negative supply to the ADC driver amplifier while preserving access to the full ADC code range. The input overvoltage clamp protects the ADC inputs against overvoltage events, minimizing disturbances on the reference pin, and eliminating the need for external protection diodes.Fast device throughput up to 1 MSPS allows users to accurately capture high frequency signals and to implement oversampling techniques to alleviate the challenges associated with antialias filter designs. Decreased serial peripheral interface (SPI) clock rate requirements reduce digital input/output power consumption, broadens digital host options, and simplifies the task of sending data across digital isolation. The SPI-compatible serial user interface is compatible with 1.8 V, 2.5 V, 3 V, and 5 V logic by using the separate VIO logic supply.APPLICATIONSAutomatic test equipmentMachine automationMedical equipmentBattery-powered equipmentPrecision data acquisition systemsInstrumentation and control systems