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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
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
Sensors
Special Edition
46 l New-Tech Magazine Europe