Sensor-to-host interface & front-end multiplexes 16 inputs

July 07, 2015 // By Graham Prophet
This 16:1 sensor interface connects multiple bridge sensors to MCUs or FPGAs; the XR10910 simplifies sensor conditioning with integrated MUX, DAC, PGA and LDO.

Exar’s highly integrated sensor interface analogue front end (AFE) provides calibration of sensor outputs: the XR10910 offers an onboard 16:1 differential multiplexer, offset correction DAC, programmable gain instrumentation amplifier and voltage reference. This AFE provides 14-bit signal path linearity and is designed to connect multiple bridge sensors to a microcontroller (MCU) or field-programmable gate array (FPGA) with an embedded ADC.

The integrated DAC provides offset calibration for any offset voltage generated by bridge sensors, improving overall system sensitivity and accuracy. An independent offset value can be set for each of the 16 differential inputs. The XR10910 allows the designer to select from eight fixed-gain settings (from 2V/V to 760V/V) to ensure the amplified sensor signal falls within the optimum input range of the downstream ADC. The integrated LDO provides a regulated voltage to power the sensors and is selectable between 3V and 2.65V for lower voltage compatibility. An I ²C serial interface provides control of the XR10910’s functions.

The XR10910 operates from 2.7V to 5V supplies and offers a digital supply range of 1.8V to 5V. It typically consumes 457 µA of supply current and offers a sleep mode which reduces the supply current to only 45 µA.

In a 6 x 6 mm QFN package pricing starts at $8.10 (1,000).

Summary of features:

• Designed to interface multiple bridge sensors with an MCU or FPGA

• Integrated features simplify sensor conditioning

• 16:1 differential MUX, programmable gain INA, LDO and offset correction DAC

• Eight selectable voltage gains from 2V/V to 760V/V with only ±0.5% gain error

• 6 x 6 mm QFN-40 package