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R01UH0336EJ0102 Rev.1.02
Page 1532 of 1538
Jul 17, 2014
V850E2/PG4-L
Section 27 Electrical Characteristics
Caution 1.
Implement the following countermeasures to minimize any adverse effect on
precision of the A/D converter from the switching noise of the digital circuit.
i. Use one full side of the board for the power-supply wiring or connect the
wiring in as large a grid pattern as possible.
ii. Insert a bypass capacitor in the vicinity of the pin lead between power
supply pins (V
DD
, EV
DD
, OSCV
DD
, or AV
DD0
) and ground pin (V
SS
, EV
SS
,
OSCV
SS
, or AV
SS0
), and between the analog reference voltage pins
(AV
REF0P
or AV
REF0M
) and the analog ground pin (AV
SS0
).
iii. We recommend isolating the analog power supply (AV
DD0
) from the
digital power supply (V
DD
, EV
DD
, or OSCV
DD
) and supplying power via a
series-connected regulator. When a common power supply is to be used,
connect the analog power-supply line, digital power-supply line, and an
electrolytic capacitor at a point in the source of the supply but wire the
power supplies in isolation from each other on the board. Insert a chip
inductor at the point of entry for the analog power supply voltage. In
addition, earth the analog ground, digital ground, and an electrolytic
capacitor at a point in the source of the power supply, but wire them in
isolation from each other on the board.
Caution 2.
Connect resistor Re and capacitor Ce to the analog input pin (
ADCA0Im
)
externally to eliminate noise (
m = 01 to 18
).
Caution 3.
When the buffer amplifier is used or when the channel S/H is used, the signal
source impedance should be equal to or less than 3 k
Ω
. In other cases, it
should be equal to or less than 200
Ω
.
Note
Full-scale range (%FSR) is the ratio, as a percentage, of the extremes of the
range of analog input voltages that can be converted, and is expressed as
follows regardless of the resolution.
1%FSR = (Maximum value of convertible analog input voltage - Minimum
value of convertible analog input voltage)/100
= (AV
REF0P
- 0) / 100
= AV
REF0P
/ 100
1 LSB is as follows at a resolution of 10 bits:
1LSB = 1/2
10
= 0.098%FSR