New-Tech Europe Magazine | Feb 2017

Sensors Special Edition

and integrates a 16:1 differential multiplexor, a programmable gain instrumentation amplifier (PGA), a 10-bit offset correction DAC (digital- to-analog converter) and an LDO (Low-dropout regulator). As shown in Figure 2. The XR10910 AFE allows each Hall Effect Sensor to have a unique

amplification and offset correction path. This function can be handled discretely but with approximately two times the footprint and four times the power consumption, refer to the example shown in the table below. There are many ways to implement a discrete solution for this function, the below table

takes only one into account. In most cases, an AFE will have a total footprint advantage over its discrete counterpart. Performance Comparison When it comes to performance, the end application plays a crucial role when deciding between a discrete and a more integrated solution. There are literally thousands of precision amplifiers on the market with varying price/ performance tradeoffs. And only a handful of integrated AFEs. When manufacturers develop an AFE, they typically have set applications in mind which dictate the overall performance specifications of the device. The XR10910 mentioned above offers 1mV maximum offset voltage, 2µVpp noise, and a gain range of 2V/V to 760V/V. Although this may be adequate for some applications it most

Figure 1: The Signal Conditioning Block conditions analog sensor signals for use by downstream MCUs or FPGAs with integrated ADCs

Figure 2: XR10910 as Hall Effect Sensor Interface AFE

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