Analog - ADC Selection
January 20, 2005
Document No. 001-33719 Rev. **
Author: Dennis Seguine
Associated Project: No
Associated Part Family: CY8C24/27/29xxx
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Software Version: NA
Associated Application Notes: AN2095, AN2219
Application Note Abstract
This Application Note outlines features and performance of the wide array of PSoC® Analog-to-Digital Converters and
provides guidance for selecting the most suitable converter for an application.
Most PSoC applications utilize an Analog-to-Digital
Converter (ADC). PSoC Designer presents dozens of
ADCs with different resolutions, sampling rates, Signal-to-
Noise Ratios (SNR), and resource utilization. This is
evident in the ADC selection window of PSoC Designer
Version 4.2, shown in Figure 1.
Figure 1. PSoC Designer v. 4.2 ADC Choices
This Application Note provides a brief review of the
operation of each type of ADC and a guide for selecting
which converter is most suitable to the PSoC-based
system being designed. For an overall understanding,
read the whole Application Note.
For an in-depth tutorial on ADC implementation and
internal waveforms, review the ADC selection webcast of
March 2004, available at www.cypress.com. For quick
guidance to converter selection, jump to the Selection
Guide on page ten of this Application Note.
Conversion of an analog signal to a digital representation
requires regularity and precision for useful data. We'll start
with a few definitions.
Range is the difference between the minimum and
maximum values measured by the ADC. In PSoC, this is
set by the references set in the Global Resource window
of PSoC Designer.
Signals that are based on absolute voltages, such as
power supply monitors or remote sensors, generally use a
reference setting based on the PSoC's internal bandgap.
This includes the reference 2*VBG +/- VBG (1.3 to 3.9V)
for differential or analog ground referenced signals and
VBG +/- VBG (0 to 2.6V) for 3.3V system