CHAPTER 11 8-BIT A/D CONVERTER (
µ
PD789104, 789124 SUBSERIES)
User’s Manual U13045EJ2V0UM00
136
Figure 11-1. Block Diagram of 8-Bit A/D Converter
(1) Successive approximation register (SAR)
The SAR receives the result of comparing an analog input voltage and a voltage at a voltage tap (comparison
voltage), received from the series resistor string, starting from the most significant bit (MSB).
Upon receiving all the bits, down to the least significant bit (LSB), that is, upon the completion of A/D
conversion, the SAR sends its contents to A/D conversion result register 0 (ADCR0).
(2) A/D conversion result register 0 (ADCR0)
ADCR0 holds the result of A/D conversion. Each time A/D conversion ends, the conversion result received
from the successive approximation register is loaded into ADCR0, which is an 8-bit register that holds the result
of A/D conversion.
ADCR0 can be read with an 8-bit memory manipulation instruction.
RESET input makes this register undefined.
(3) Sample and hold circuit
The sample and hold circuit samples consecutive analog inputs from the input circuit, one by one, and sends
them to the voltage comparator. The sampled analog input voltage is held during A/D conversion.
(4) Voltage comparator
The voltage comparator compares an analog input with the voltage output by the series resistor string.
ANI0/P60
ANI1/P61
ANI2/P62
ANI3/P63
Selector
Sample and hold circuit
Voltage comparator
Successive
approximation
register (AR)
Control
circuit
2
A/D conversion result
register 0 (ADCR0)
Tap selector
AV
SS
INTAD0
A/D converter mode register 0
(ADM0)
A/D input selection
register 0 (ADS0)
Internal bus
AV
SS
ADCS0 FR02
FR01
FR00
ADS01 ADS00
P-ch
AV
DD
Summary of Contents for mPD789101
Page 2: ...2 User s Manual U13045EJ2V0UM00 MEMO...
Page 10: ...10 User s Manual U13045EJ2V0UM00 MEMO...
Page 16: ...User s Manual U13045EJ2V0UM00 16 MEMO...
Page 46: ...User s Manual U13045EJ2V0UM00 46 MEMO...
Page 72: ...72 User s Manual U13045EJ2V0UM00 MEMO...
Page 86: ...User s Manual U13045EJ2V0UM00 86 MEMO...
Page 94: ...User s Manual U13045EJ2V0UM00 94 MEMO...
Page 102: ...User s Manual U13045EJ2V0UM00 102 MEMO...
Page 128: ...User s Manual U13045EJ2V0UM00 128 MEMO...
Page 148: ...User s Manual U13045EJ2V0UM00 148 MEMO...
Page 162: ...User s Manual U13045EJ2V0UM00 162 MEMO...
Page 218: ...User s Manual U13045EJ2V0UM00 218 MEMO...
Page 238: ...User s Manual U13045EJ2V0UM00 238 MEMO...
Page 240: ...User s Manual U13045EJ2V0UM00 240 MEMO...
Page 256: ...User s Manual U13045EJ2V0UM00 256 MEMO...
Page 258: ...258 User s Manual U13045EJ2V0UM00 MEMO...