SX8801IRXXMLTRT View Datasheet(PDF) - Semtech Corporation
Part Name
Description
MFG CO.
'SX8801IRXXMLTRT' PDF : 135 Pages View PDF
XE8801A – SX8801R
Like most ADCs intended for instrumentation or sensing applications, the ZoomingADC™ is an over-sampled
converter (See Note1). The ADC is a so-called incremental converter, with bipolar operation (the ADC accepts both
positive and negative input voltages). In first approximation, the ADC output result relative to full-scale (FS) delivers
the quantity:
OUTADC ≅ VIN , ADC
FS / 2 VREF / 2
(Eq. 1)
in two's complement (see Sections 16.4 and 16.7 for details). The output code OUTADC is -FS/2 to +FS/2 for VIN,ADC ≅
-VREF/2 to +VREF/2 respectively. As will be shown in section 16.6, VIN,ADC is related to input voltage VIN by the
relationship:
VIN , ADC = GDTOT ⋅VIN − GDoffTOT ⋅VREF (V)
(Eq. 2)
where GDTOT is the total PGA gain, and GDoffTOT is the total PGA offset.
Inputs
0
1
2
AC_A
3
4
5
6
7
fS
PGA1
VIN
GD1
PGA2
GD2
OFF2
PGA3
GD3
fS
VIN,ADC
ADC
OFF3
0
AC_R
1
2
3
VREF
5
2
4
7
RegACCfg5
RegACCfg4
RegACCfg3
RegACCfg2
RegACCfg1
RegACCfg0
Power Saving Modes
PGA Enabling
Conversion Start
Nbr of Elementary Cycles
Over-Sampling Ratio
Continuous vs. On-Request
7 Acquisition Chain
Register Bank
8
RegACOutLSB
8
RegACOutMSB
ADC Busy Flag
Default Settings
Sampling Frequency fS
Figure 16-2. ZoomingADC™ detailed functional block diagram
1 Note: Over-sampled converters are operated with a sampling frequency fS much higher than the input signal's Nyquist rate (typically fS is 20-
1'000 times the input signal bandwidth). The sampling frequency to throughput ratio is large (typically 10-500). These converters include digital
decimation filtering. They are mainly used for high resolution, and/or low-to-medium speed applications.
© Semtech 2005
16-5
www.semtech.com
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