Precision ADC with I2c compatible interface

     The AD7291 is a 12-bit, low-power, 8-channel Successive approximation register (SAR) analog-to-digital converter (ADC) with built-in temperature sensors. The ADC is powered by a 3.3V power supply and has an I2c compatible interface. This section includes a 9-channel multiplexer and a track-hold amplifier that can handle frequencies up to 30 MHZ. The device has an on-chip 2.5V reference that can be disabled to allow the use of external references.

     The AD7291 provides a 2-wire serial interface compatible with the I2C interface. The I2C interface supports standard and fast I2C interface modes. Adcs usually keep part of the power off when not switching, and power on when switching. The conversion process can be controlled through command mode, where the conversion occurs during an I2C write operation or through software control of the selected autocycle mode.

     The AD7291 includes a high-precision bandgap temperature sensor that is monitored and digitized by a 12-bit ADC, providing a resolution of 0.25°C. The device provides a programmable sequencer that is able to select a pre-programmable sequence of channels for conversion. The chip upper limit register can be programmed to set the highest and lowest limits for the conversion result; An out-of-range indicator output (alert) becomes active when a high or low limit set by the program is violated by a conversion result. This output can be used as an interrupt.