Renesas M32R/ECU Series, User Manual

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11
11-33
A-D Converters
32180 Group User's Manual (Rev.1.0)
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] =
A-D conversion result x VREF input voltage [V]
1,024
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.”
11.3 Functional Description of A-D Converters
Figure 11.3.1 Outline Block Diagram of the Successive Approximation-type A-D Converter Unit
ADiIN0
ADiIN1
ADiIN2
ADiIN3
ADiIN4
ADiIN5
ADiIN6
ADiIN7
ADiIN8
ADiIN9
ADiIN10
ADiIN11
ADiIN12
ADiIN13
ADiIN14
Selector
AVSSi
VREFi
10-bit A-Di Successive
Approximation Register
(ADiSAR)
10-bit
A-Di Data Register
A-Di Comparate
Data Register
A-D Control Circuit
10-bit D-A Converter
Comparator
ADiCMP
ADiDT0–15
Successive Approximation-type
A-D Converter Unit
AVCCi
Vref
VIN
i = 0, 1
Sample-and-Hold
Control Circuit
ADiIN15