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AD7291 8-Channel 12-Bit SAR ADC

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AD7291 8-Channel 12-Bit SAR ADC

Analog Devices’ precision ADC with an I²C-compatible interface

ADI's AD7291 is a 12-bit, low power, 8-channel successive approximation register (SAR) analog-to-digital converter (ADC) with an internal temperature sensor. This ADC operates from a single 3.3 V power supply and features an I²C-compatible interface. The part 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 I²C interfaces. The I²C interface supports standard and fast I²C interface modes. The ADC 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 I²C write operations or an autocycle mode selected through software control.

The AD7291 includes a high accuracy bandgap temperature sensor, which is monitored and digitized by the 12-bit ADC to give a resolution of 0.25°C. The device offers a programmable sequencer, which enables the selection of a pre-programmable sequence of channels for conversion. On-chip limit registers can be programmed with high and low limits for the conversion results; an out-of-range indicator output (ALERT) becomes active when the programmed high or low limits are violated by the conversion result. This output can be used as an interrupt.

Features
  • 12-bit SAR ADC
    • 8 single-ended analog input channels
    • Analog input range: 0 V to 2.5 V
  • 12-bit temperature-to-digital converter
    • Temperature sensor accuracy of ±1°C typical
  • Channel sequencer operation
  • Specified for VDD of 2.8 V to 3.6 V
  • Logic voltage VDRIVE = 1.65 V to 3.6 V
  • Internal 2.5 V reference
Highlights
  • Ideally suited to monitoring system variables in a variety of systems including telecommunications, process control, and industrial control
  • I²C-compatible serial interface, which supports standard and fast modes
  • Automatic partial power-down while not converting to maximize power efficiency
  • Channel sequencer operation
  • Integrated temperature sensor with 0.25°C resolution
  • Out of range indicator that can be software disabled or enabled