NEC V850E/PH2, User Manual

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Chapter 14 A/D Converter
User’s Manual U16580EE3V1UD00
14.2 Configuration
The A/D converter of the V850E/PH2 adopts the successive approximation method, and uses A/D con-
verter n mode registers 0, 1, 2 (ADMn0, ADMn1, ADMn2), and the A/D conversion result register
(ADCRn0 to ADCRn9) to perform A/D conversion operations (n = 0, 1).
(1) Input circuit
The input circuit selects the analog input (ANIn0 to ANIn9) according to the mode set by the
ADMn0, ADMn1, and ADMn2 registers.
(2) C-Array
Holds the charge of the differential voltage between the voltage input from the analog input pins
(ANIn0 to ANIn9) and the reference voltage (1/2 AV
DD
), and redistributes the sampled charges.
(3) C-Dummy
This block holds the reference voltage (1/2 AV
DD
) and assigns the reference of the comparator
input.
(4) Voltage comparator
The voltage comparator compares the C-Array comparison potential with the C-Dummy reference
potential.
(5) A/D conversion result register (ADCRnm), A/D conversion result register nH (ADCRnmH)
(n = 0, 1)(m = 0 to 9)
ADCRnm is a 10-bit register that holds A/D conversion results. Each time A/D conversion is
completed, the conversion results are loaded from the successive approximation register (SAR).
RESET input makes this register undefined.
(6) A/D conversion result register for DMA transfer (ADDMAn) (n = 0, 1)
ADDMAn is a 16-bit register that holds the last 10-bit A/D conversion result and an over rung flag
for indicating a DMA transfer failure.
(7) ANIn0 to ANIn9 pins (n = 0, 1)
These are 10-channel analog input pins for the A/D converter n. They input the analog signals to
be A/D converted.
Caution: Make sure that the voltages input to ANIn0 to ANIn9 do not exceed the rated values. If
a voltage higher than AV
DD
or lower than AV
SSn
(even within the range of the absolute
maximum ratings) is input to a channel, the conversion value of the channel is
undefined, and the conversion values of the other channels may also be affected.
(8) AV
REFn
pins (n = 0, 1)
This is the pin for inputting the reference voltage of the A/D converter. It converts signals input to
the ANIn0 to ANIn9 pins to digital signals based on the voltage applied between AV
SSn
and
AV
REFn
.