Semtech 2005
www.semtech.com
16-1
XE8801A – SX8801R
16.
Acquisition
Chain
16.1
ZoomingADC
Features .................................................................................................................... 16-2
16.2
Overview .............................................................................................................................................. 16-2
16.3
Register map ....................................................................................................................................... 16-3
16.4
ZoomingADC
Description................................................................................................................ 16-4
16.4.1
Acquisition Chain .................................................................................................................................. 16-4
16.4.2
Peripheral Registers.............................................................................................................................. 16-6
16.4.3
Continuous-Time vs. On-Request ......................................................................................................... 16-7
16.5
Input Multiplexers ............................................................................................................................... 16-8
16.6
Programmable Gain Amplifiers.......................................................................................................... 16-9
16.6.1
PGA & ADC Enabling.......................................................................................................................... 16-10
16.6.2
PGA1 .................................................................................................................................................. 16-10
16.6.3
PGA2 .................................................................................................................................................. 16-11
16.6.4
PGA3 .................................................................................................................................................. 16-11
16.7
ADC Characteristics ......................................................................................................................... 16-12
16.7.1
Conversion Sequence ......................................................................................................................... 16-12
16.7.2
Sampling Frequency ........................................................................................................................... 16-12
16.7.3
Over-Sampling Ratio........................................................................................................................... 16-13
16.7.4
Elementary Conversions ..................................................................................................................... 16-13
16.7.5
Resolution ........................................................................................................................................... 16-14
16.7.6
Conversion Time & Throughput .......................................................................................................... 16-15
16.7.7
Output Code Format ........................................................................................................................... 16-15
16.7.8
Power Saving Modes .......................................................................................................................... 16-17
16.8
Specifications and Measured Curves .............................................................................................. 16-17
16.8.1
Default Settings................................................................................................................................... 16-17
16.8.2
Specifications...................................................................................................................................... 16-18
16.8.3
Linearity .............................................................................................................................................. 16-20
16.8.3.1
Integral non-linearity............................................................................................................................ 16-20
16.8.3.2
Differential non-linearity ...................................................................................................................... 16-23
16.8.4
Noise................................................................................................................................................... 16-24
16.8.5
Gain Error and Offset Error ................................................................................................................. 16-25
16.8.6
Power Consumption............................................................................................................................ 16-26
16.8.7
Power Supply Rejection Ratio............................................................................................................. 16-28
16.9
Application Hints............................................................................................................................... 16-29
16.9.1
Input Impedance ................................................................................................................................. 16-29
16.9.2
PGA Settling or Input Channel Modifications....................................................................................... 16-29
16.9.3
PGA Gain & Offset, Linearity and Noise.............................................................................................. 16-29
16.9.4
Frequency Response .......................................................................................................................... 16-30
16.9.5
Power Reduction................................................................................................................................. 16-31
Not
Recommended
for
New
Designs