The AD7291 is a 12-bit， low power， 8-channel， successive approximation analog-to-digital converter （ADC） with an internal temperature sensor. The device operates from a single 3.3 V power supply and features an I2 C-compatible interface. The device contains a 9- channel multiplexer and a track-and-hold amplifier than can handle frequencies up to 30 MHz. The device has an on-chip 2.5 V reference that can be disabled to allow the use of an external reference. The AD7291 provides a 2-wire serial interface compatible with I 2 C interfaces. The I2 C interface supports standard and fast I2 C interface modes. The AD7291 normally remains in a partial power-down state while not converting and powers up for conversions. The conversion process can be controlled by a command mode where conversions occur across I2 C write operations or an autocycle mode selected through software control. The AD7291 includes a high accuracy band gap temperature sensor， which is monitored and digitized by the 12-bit ADC to give a resolution of 0.25°C. The AD7291 offers a programmable sequencer， which enables the selection of a preprogrammable sequence of channels for conversion.