Internal Equivalent Circuit Of Analog Input Block - Renesas R8C Series User Manual

R8C/1A Group, R8C/1B Group
17.5

Internal Equivalent Circuit of Analog Input Block

Figure 17.8 shows the Internal Equivalent Circuit of Analog Input Block.
VCC
Parasitic diode ON resistor
approx. 2 k Ω Wiring resistor
AN8
Parasitic diode
VSS
i = 4
ON resistor
approx. 2 k Ω Wiring resistor
AN11
A/D control register 0
VREF
AVSS
Comparison reference voltage
Control signal
for SW2
Control signal
for SW3
NOTE:
1. Use this data only as a guideline for circuit design.
Mass production may cause some changes in device characteristics.
Figure 17.8 Internal Equivalent Circuit of Analog Input Block
Rev.1.30 Dec 08, 2006
REJ09B0252-0130
VCC VSS
ON resistor
approx. 0.6 k Ω
approx. 0.2 k Ω
SW1
SW2
Sampling
control signal
i ladder-type
i ladder-type
switches
wiring resistors
approx. 0.2 k Ω
SW1
b2 b1 b0
Reference
control signal
Resistor
ON resistor
ladder
approx. 0.6 k f
(Vref) generator
Sampling Com parison
Connect to
Connect to
Connect to
Connect to
Page 241 of 315
C = Approx.1.5 pF
Analog input
voltage
VIN
SW4
Vref
Comparison
SW2
voltage
SW1 conducts only to the ports selected for analog input.
SW2 and SW3 are open when A/D conversion is not in progress;
their status varies as shown by the waveforms in the diagrams at left.
SW4 conducts only when A/D conversion is not in progress.
AVCC
AMP
ON resistor
approx. 5 k Ω
SW3
Chopper-type
amplifier
AVSS
A/D successive
conversion register
A/D conversion
interrupt request
17. A/D Converter