SX8723 View Datasheet(PDF) - Semtech Corporation
Part Name
Description
MFG CO.
'SX8723' PDF : 53 Pages View PDF
SX8723
ZoomingADC™ for Pressure and Temperature Sensing
ADVANCED COMMUNICATIONS & SENSING
The output of the PGA stages is directly fed to the analog-to-digital converter (ADC), which converts the signal
VIN,ADC into digital.
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 differential input voltages). In first approximation, the ADC output result relative to
full-scale (FS) delivers the quantity:
OUTADC ≅ VIN , ADC
FS / 2 VREF ,ADC / 2
Equation 1
in two's complement (see Equation 4 and Equation 5 for details). The output code OUTADC is -FS/2 to +FS/2 for
VIN,ADC ≅ -VREF,ADC/2 to +VREF,ADC/2 respectively. As will be shown, VIN,ADC is related to input voltage VIN by the
relationship:
VIN , ADC = GDTOT ⋅VIN − GDoffTOT ⋅VREF ,ADC (V)
Equation 2
where GDTOT is the total PGA gain, and GDoffTOT is the total PGA offset.
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.
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