XE8805 SEMTECH [Semtech Corporation], XE8805 Datasheet - Page 88

• Manufacturer Part Number: XE8805
• Description: Data Acquisition MCU
• Manufacturer: SEMTECH [Semtech Corporation]

16.1 ZoomingADC™ Features
The ZoomingADC™ is a complete and versatile low-power analog front-end interface typically intended for sensing
applications. The key features of the ZoomingADC™ are:
Programmable 6 to 16-bit dynamic range oversampled ADC
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16.2 Overview
The total acquisition chain consists of an input multiplexer, 3 programmable gain amplifier stages and an
oversampled A/D converter. The reference voltage can be selected on two different channels. Two offset
compensation amplifiers allow for a wide offset compensation range. The programmable gain and offset allow one
to zoom in on a small portion of the reference voltage defined input range.
16.3 Register map
There are eight registers in the acquisition chain (AC), namely RegAcOutLsb, RegAcOutMsb, RegAcCfg0,
RegAcCfg1, RegAcCfg2, RegAcCfg3, RegAcCfg4 and RegAcCfg5. Table 16-2 to Table 16-9 show the mapping
of control bits and functionality of these registers while Table 16-1 gives an overview of these eight.
The register map only gives a short description of the different configuration bits. More detailed information is found
in subsequent sections.
© Semtech 2006
Flexible gain programming between 0.5 and 1000
Flexible and large range offset compensation
4-channel differential or 8-channel single-ended input multiplexer
2-channel differential reference inputs
Power saving modes
Direct interfacing to CoolRisc™ microcontroller
Reference
Analog
Inputs
Inputs
0
1
2
3
4
5
6
7
0
1
2
3
Reference
Figure 16-1. ZoomingADC™ general functional block diagram
Selection
Selection
Input
V
IN
f
V
S
Gain1 Gain2
REF
PGA1
GD1
V
D1
Offset2
OFF2
PGA2
GD2
16-2
ZOOM
Gain3
V
D2
Offset3
OFF3
PGA3
GD3
V
IN,ADC
ADC
f
S
XE8805/05A
16
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