Functional Description Of A-D Converters; How To Find Analog Input Voltages - Renesas M32R/ECU Series User Manual

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11.3 Functional Description of A-D Converters

11.3.1 How to Find Analog Input Voltages

The A-D Converters perform A-D conversion using a 10-bit successive approximation method as will be de-
scribed later. The equation shown below is used to calculate the actual analog input voltage from the digital
value obtained by executing A-D conversion.
Analog input voltage [v] =
The A-D Converters are a 10-bit converter, providing a resolution of 1,024 discrete voltage levels. Because the
reference voltage for the A-D Converters is the voltage applied to the VREF pin, make sure that an exact and
stable constant-voltage power supply is connected to VREF. Also make sure the analog circuit power supply
and ground (AVCC, AVSS) are separated from those of the digital circuit, with sufficient noise prevention mea-
sures incorporated.
For details about the conversion accuracy, see Section 11.3.5, "Accuracy of A-D Conversion."
AVCCi
AVSSi
VREFi
ADiIN0
ADiIN1
ADiIN2
ADiIN3
ADiIN4
ADiIN5
ADiIN6
ADiIN7
ADiIN8
ADiIN9
ADiIN10
ADiIN11
ADiIN12
ADiIN13
ADiIN14
ADiIN15
Figure 11.3.1 Outline Block Diagram of the Successive Approximation-type A-D Converter Unit
11.3 Functional Description of A-D Converters
A-D conversion result x VREF input voltage [V]
10-bit
ADiDT0–15
A-Di Data Register
A-Di Comparate
ADiCMP
Data Register
10-bit A-Di Successive
Approximation Register
(ADiSAR)
Vref
10-bit D-A Converter
VIN
Sample-and-Hold
Control Circuit
Selector
Successive Approximation-type
A-D Converter Unit
11-33
1,024
i = 0, 1
A-D Control Circuit
Comparator
32180 Group User's Manual (Rev.1.0)
A-D Converters