New-Tech Europe Magazine | Feb 2017

Sensors Special Edition

Integrated AFE (XR10910)

Discrete Solution

Function

Footprint

Power Consumption

Footprint

Power Consumption

~ 7mm x 7mm (16:1 diff MUX in LFCSP) ~ 4mm x 3.75mm (Digitally program- mable amp in LFCSP) ~2mm x 2mm (10- bit DAC in SC70) + ~2mm x 2mm (amp in SC70) ~2mm x 2mm (LDO in LFCSP)

16:1 differential mux

~0.01mA

Digitally controlled PGA

~1.8mA

6mm x 6mm (QFN)

0.5mA

Offset correction

~0.08mA + ~0.1mA

LDO to power sensors

~0.09mA

0.5mA

76mm2

2.08mA

Total

36mm 2

size, power, and time to market if you happen to be designing an ECG (electrocardiogram) or other medical diagnostic equipment. But if you are a designer with the challenge of conditioning multiple Hall Effect sensors, as described above, this highly integrated AFE is not the answer. Something with less integration and more flexibility is needed. Conclusion Sensor interface AFEs tend to offer faster time to market, higher ease of use, smaller footprint and in many cases lower power. But many are extremely specialized for certain applications and are not able to support multiple sensors or multiple types of sensors. Discrete solutions tend to be more flexible and can be fine-tuned to each specific application, but they require analog design prowess, more real-estate, more power, and tend to lack many automated features like auto calibration to correct for sensor drift. The XR10910 feature set truly

certainly will not fit every sensor interface requirement out there. If performance is the designers’ top priority and you cannot find an AFE on the market designed specifically for your application, then a discrete solution will usually be the preferred method because the designer can hand-pick the components to best fit his/her needs. Ultimately fine tuning the sensor conditioning block. Comparing AFEs AFEs on the market today offer different levels of integration. Some include an ADC or processing power, while others like the XR10910 do not. Most sensor interface AFEs on the market are very application specific, thus their performance feature set and functional blocks are extremely useful when used in the target application. For example, there are several AFEs on the market today that were designed for medical instrumentation applications and integrate 16-bit or 24-bit delta- sigma ADCs, PGAs and a host of features designed to reduce

unique in the market, filling the gap between less feature rich discrete solutions and single-chip sensor interface AFEs that include processing power. Consuming only 457µA supply current and only 36mm2 of real-estate, the XR10910 offers the industry’s smallest, lowest power interface for 16 analog sensors. The XR10910 will be the first in a growing family of easy- to-use sensor interface products from Exar. Smaller channel count versions are on the horizon as well as versions that offer digital outputs. Sensors enable the smart products and technology we use every day. Sensor conditioning products like the XR10910 will continue to play a key role in how these sensors interface with our ever growing digital world. Designers will continue to weigh the benefits of integrated AFEs versus discrete solutions and semiconductor manufacturers will continue to expand the AFEs offered in an effort to supply AFEs to a broader market space.

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