Phytec miniMODUL-537, Hardware Manual

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A/D Converter of the SAB80C537
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PHYTEC Meßtechnik GmbH 1993 L-006e_2
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9 A/D Converter of the SAB80C537
The internal A/D converter of this controller is a real 8-bit converter.
The twelve analog inputs are switched by an 12:1 analog multiplexer.
The converter has the feature that the conversion range for 8-bit
resolution is programmable in ratios of the external applied reference
voltage. The minimal size of the conversion window should not be
less than 1 V.
The converter of the SAB80C537 is very suitable for many applica-
tions, but doesn’t replace a converter of high precision. For your
applications consider, if the specifications of the converter from
INFINEON satisfies your expectation. An additional external conver-
ter chip is easily connected to the miniMODUL-537.
The external reference voltage VAREF and VAGND are close to
VCC and GND. Intermediate values are not permitted. The converter
does not operate without external reference voltages VAREF and
VAGND. The reference voltages have to be connected to the analog
connecting stripe C. The handling of the integrated A/D converter of
the 80C537 is compatible to the 80C535. The connections for this
purpose are SFR, ADDAT, ADCON0, ADCON1 and DAPR. AD-
CON0 corresponds to the SFR ADCON of the 80C535. ADCON1 is
used to select the twelve analog inputs. The software of the 80C535
will operate the lower eight channels correctly.
As already mentioned, the informations concerning the accuracy of
the converter are found in the INFINEON controller manual. Since the
SAB80C537 doesn’t provide the feature of nullification, a zero devia-
tion has to be considered. This error can be compensated by software
or by adjustment of the input-amplifiers, which are often employed.