AD7291:  8-Channel, I²C, 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

1. Ideally suited to monitoring system variables in a variety of systems including telecommunications, process control, and industrial control.
2. I²C-compatible serial interface. Standard and fast modes.
3. Automatic partial power-down while not converting to maximize power efficiency.
4. Channel sequencer operation.
5. Integrated temperature sensor with 0.25°C resolution.
6. Out of range indicator that can be software disabled or enabled.