The AD76911 is an 18-bit， charge redistribution， successive approximation， analog-to-digital converter （ADC） that operates from a single power supply， VDD， between 2.3 V and 5 V. It contains a low power， high speed， 18-bit sampling ADC with no missing codes， an internal conversion clock， and a versatile serial interface port. On the CNV rising edge， it samples the voltage difference between the IN+ and IN? pins. The voltages on these pins swing in opposite phases between 0 V and REF. The reference voltage， REF， is applied externally and can be set up to the supply voltage. The part’s power scales linearly with throughput. The SPI-compatible serial interface also features the ability， using the SDI input， to daisy-chain several ADCs on a single 3-wire bus and provides an optional busy indicator. It is compatible with 1.8 V， 2.5 V， 3 V， or 5 V logic， using the separate VIO supply. The AD7691 is housed in a 10-lead MSOP or a 10-lead LFCSP with operation specified from ?40°C to +85°C.