upd70f3017ay Renesas Electronics Corporation., upd70f3017ay Datasheet - Page 323

• Manufacturer Part Number: upd70f3017ay
• Description: V850/sa1tm 32-/16-bit Single-chip Microcontroller
• Manufacturer: Renesas Electronics Corporation.

(4) Countermeasures against noise
(5) ANI0 to ANI11
(6) Input impedance of AV
Reference voltage input
To keep the resolution of 10 bits, prevent noise from being superimposed on the AV
The higher the output impedance of the analog input source, the heavier the influence of noise. To lower noise,
connecting an external capacitor as shown in Figure 11-6 is recommended.
The analog input (ANI0 to ANI11) pins function alternately as port pins.
To execute A/D conversion with any of ANI0 to ANI11 selected, do not execute an instruction that inputs data to
the port during conversion; otherwise, the resolution may drop.
If a digital pulse is applied to pins adjacent to the pin whose input signal is converted into a digital signal, the
expected A/D conversion result may not be obtained because of the influence of coupling noise. Therefore, do
not apply a pulse to the adjacent pins.
A series resistor string is connected between the AV
If the output impedance of the reference voltage source is too high, the series resistor string between the AV
and AV
SS
pins is connected in series, increasing the error of the reference voltage.
C = 100 to 1000 pF
REF
pin
Figure 11-6. Handling of Analog Input Pin
CHAPTER 11 A/D CONVERTER
User’s Manual U12768EJ4V1UD
REF
Clamp with diode with a low V
AV
and AV
AV
V
AV
AV
V
REF
DD
SS
REF
DD
SS
or lower than AV
SS
pins.
SS
may be generated.
F
(0.3 V MAX.) if noise higher than
REF
and ANI0 to ANI11 pins.
323
REF