8-Channel, IC, 12-Bit SAR ADC with Temperature Sensor

The AD7291 is a 12-bit, low power, 8-channel, successive approximation analog-to-digital converter (ADC) with an internal temperature sensor.

The part 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 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 I2C 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.

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.

Product Highlights

* Ideally suited to monitoring system variables in a variety of systems including telecommunications, process control, and industrial control.

* I2C-compatible serial interface. 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.

* 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

* See data sheet for additional features