UPD78F1502AGK-GAK-AX Datasheet, PDF (431/1031 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcontrollers

78K0R/Lx3
Reference
voltage
input
C = 100 to 1,000 pF
CHAPTER 10 12-BIT A/D CONVERTER (μ PD78F150xA),
10-BIT A/D CONVERTER (μ PD78F151xA)
Figure 10-28. Analog Input Pin Connection
If there is a possibility that noise equal to or higher than AVDD0 or
equal to or lower than AVSS may enter, clamp with a diode with a
small VF value (0.3 V or lower).
AVREFP
ANI0 to ANI10, ANI15
AVSS
VSS
(5) ANI0 to ANI10, ANI15
<1> The analog input pins (ANI0 to ANI7) are also used as input port pins (P20 to P27).
The analog input pins (ANI8 to ANI10, ANI15) are also used as input port pins (P150 to P152, P157).
When A/D conversion is performed with any of ANI0 to ANI10, and ANI15 selected, do not access P20 to P27,
P150 to P152, and P157 while conversion is in progress; otherwise the conversion resolution may be degraded.
It is recommended to select pins used as P20 to P27, P150 to P152, and P157 starting with the ANI0/P20 that
is the furthest from AVDD0.
<2> If the pins adjacent to the pins currently used for A/D conversion are used as digital I/O port, the expected value
of the A/D conversion may not be obtained due to coupling noise. Therefore, make sure that digital pulses are
not input to or output from the pins adjacent to the pin undergoing A/D conversion.
<3> If any pin among pins of ports 2 and 15 is used as digital output port during A/D conversion, the expected value
of the A/D conversion may not be obtained due to coupling noise. Therefore, make sure that digital pulses are
not output to pins of ports 2 and 15 during A/D conversion.
(6) Input impedance of ANI0 to ANI10, ANI15 pins
This A/D converter charges a sampling capacitor for sampling during sampling time.
Therefore, only a leakage current flows when sampling is not in progress, and a current that charges the capacitor
flows during sampling. Consequently, the input impedance fluctuates depending on whether sampling is in progress,
and on the other states.
To make sure that sampling is effective, however, it is recommended to keep the output impedance of the analog
input source to within 1 kΩ, and to connect a capacitor of about 100 pF to the ANI0 to ANI10 and ANI15 pins (see
Figure 10-26).
Remark 78K0R/LF3:
ANI0-ANI6, ANI15
78K0R/LG3, 78K0R/LH3: ANI0-ANI10, ANI15
R01UH0004EJ0501 Rev.5.01
415
Jun 20, 2011