UPD784044 Datasheet, PDF (35/90 Pages) NEC – 16-BIT SINGLE-CHIP MICROCONTROLLER

µPD784044(A), 784046(A)
7.5 A/D Converter
The µPD784046(A) has an analog-to-digital (A/D) converter with 16 multiplexed analog input pins (ANI0
through ANI15).
This converter is of successive approximation type. The result of conversion is stored to and retained in 10-
bit A/D conversion result registers (ADCR0-ADCR7). Therefore, high-speed, high-accuracy conversion can be
performed (conversion time: about 13.5 µs: fCLK = 12.5 MHz).
The A/D conversion operation can be started in the following modes:
• Hardware start : Conversion is started by trigger input (INTP4).
• Software start : Conversion is started by setting a bit of the A/D converter mode register (ADM).
The A/D converter operates in the following modes:
• Scan mode
• Select mode
: Sequentially selects two or more analog input pins to obtain data to be converted from all
the pins.
: Selects only one analog input pin to obtain successive conversion values.
The above modes and stopping the conversion are specified by ADM.
When the result of conversion is transferred to ADCRn (n = 0-7), interrupt request INTAD is generated. By
using this interrupt request and by using macro service, the converted value can be successively transferred
to memory.
ANI0
ANI1
ANI2
ANI3
ANI4
ANI5
ANI6
ANI7
ANI8
ANI9
ANI10
ANI11
ANI12
ANI13
ANI14
ANI15
INTP4
Figure 7-6. Block Diagram of A/D Converter
Input
selector
Input
selector
Sample & hold circuit
Voltage
comparator
Series resistor string
AVREF
R/2
R
Successive approximation
register (SAR)
Edge
detection
circuit
Conversion
trigger
Control
circuit
Trigger enable
INTAD
10
A/D converter mode register
(ADM)
8
ADCR0
ADCR1
ADCR2
ADCR3
ADCR4
ADCR5
ADCR6
ADCR7
10
R/2
AVSS
A/D conversion result register
Internal bus
35