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Semtech 2006
www.semtech.com
17-1
XE8802 Sensing Machine Data Acquisition MCU
with ZoomingADC and LCD driver
17.
Acquisition
Chain
17.1
ZOOMINGADC FEATURES ....................................................................................................... 17-2
17.2
OVERVIEW ................................................................................................................................. 17-2
17.3
REGISTER MAP........................................................................................................................... 17-2
17.4
ZOOMINGADC DESCRIPTION ................................................................................................... 17-4
17.4.1
Acquisition Chain ..................................................................................................................... 17-4
17.4.2
Peripheral Registers................................................................................................................. 17-5
17.4.3
Continuous-Time vs. On-Request ............................................................................................ 17-7
17.5
INPUT MULTIPLEXERS ................................................................................................................. 17-7
17.6
PROGRAMMABLE GAIN AMPLIFIERS.............................................................................................. 17-8
17.6.1
PGA & ADC Enabling............................................................................................................. 17-10
17.6.2
PGA1 ..................................................................................................................................... 17-10
17.6.3
PGA2 ..................................................................................................................................... 17-10
17.6.4
PGA3 ..................................................................................................................................... 17-10
17.7
ADC CHARACTERISTICS ........................................................................................................... 17-11
17.7.1
Conversion Sequence ............................................................................................................ 17-11
17.7.2
Sampling Frequency .............................................................................................................. 17-12
17.7.3
Over-Sampling Ratio.............................................................................................................. 17-12
17.7.4
Elementary Conversions ........................................................................................................ 17-13
17.7.5
Resolution .............................................................................................................................. 17-13
17.7.6
Conversion Time & Throughput ............................................................................................. 17-14
17.7.7
Output Code Format .............................................................................................................. 17-14
17.7.8
Power Saving Modes ............................................................................................................. 17-16
17.8
SPECIFICATIONS AND MEASURED CURVES ................................................................................. 17-16
17.8.1
Default Settings...................................................................................................................... 17-16
17.8.2
Specifications......................................................................................................................... 17-17
17.8.3
Linearity ................................................................................................................................. 17-18
17.8.3.1 Integral non-linearity.................................................................................................................................... 17-18
17.8.3.2 Differential non-linearity .............................................................................................................................. 17-22
17.8.4
Noise...................................................................................................................................... 17-23
17.8.5
Gain Error and Offset Error .................................................................................................... 17-24
17.8.6
Power Consumption............................................................................................................... 17-25
17.8.7
Power Supply Rejection Ratio................................................................................................ 17-27
17.9
APPLICATION HINTS.................................................................................................................. 17-28
17.9.1
Input Impedance .................................................................................................................... 17-28
17.9.2
PGA Settling or Input Channel Modifications.......................................................................... 17-28
17.9.3
PGA Gain & Offset, Linearity and Noise................................................................................. 17-28
17.9.4
Frequency Response ............................................................................................................. 17-29
17.9.5
Power Reduction.................................................................................................................... 17-29
Not
Recommended
for
New
Designs