UPD78F0411GA-GAM-AX Datasheet, PDF (294/564 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 12 10-BIT SUCCESSIVE APPROXIMATION TYPE A/D CONVERTER (μPD78F041x only)
12.2 Configuration of 10-Bit Successive Approximation Type A/D Converter
The 10-bit successive approximation type A/D converter includes the following hardware.
(1) ANI0 to ANI5 pins
These are the 6-channel analog input pins of the 10-bit successive approximation type A/D converter. They input
analog signals to be converted into digital signals. Pins other than the one selected as the analog input pin can
be used as I/O port pins or segment output pins.
(2) Sample & hold circuit
The sample & hold circuit samples the input voltage of the analog input pin selected by the selector when A/D
conversion is started, and holds the sampled voltage value during A/D conversion.
(3) Series resistor string
The series resistor string is connected between AVREF and AVSS, and generates a voltage to be compared with
the sampled voltage value.
Figure 12-2. Circuit Configuration of Series Resistor String
AVREF
AVSS
P-ch
ADCS
Series resistor string
(4) Voltage comparator
The voltage comparator compares the sampled voltage value and the output voltage of the series resistor string.
(5) Successive approximation register (SAR)
This register converts the result of comparison by the voltage comparator, starting from the most significant bit
(MSB).
When the voltage value is converted into a digital value down to the least significant bit (LSB) (end of A/D
conversion), the contents of the SAR register are transferred to the A/D conversion result register (ADCR).
(6) 10-bit A/D conversion result register (ADCR)
The A/D conversion result is loaded from the successive approximation register to this register each time A/D
conversion is completed, and the ADCR register holds the A/D conversion result in its higher 10 bits (the lower 6
bits are fixed to 0).
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User’s Manual U18698EJ1V0UD