MC9S12E128 MOTOROLA [Motorola, Inc], MC9S12E128 Datasheet - Page 141

• Manufacturer Part Number: MC9S12E128
• Description: MC9S12E-Family Device User Guide V01.04
• Manufacturer: MOTOROLA [Motorola, Inc]

B.7.3.2 Source capacitance
When sampling an additional internal capacitor is switched to the input. This can cause a voltage drop due
to charge sharing with the external and the pin capacitance. For a maximum sampling error of the input
voltage ≤ 1LSB, then the external filter capacitor, C
B.7.3.3 Current injection
There are two cases to consider.
Conditions are shown in Table A-4 unless otherwise noted
Num
1. A current is injected into the channel being converted. The channel being stressed has conversion
2. Current is injected into pins in the neighborhood of the channel being converted. A portion of this
1
2
3
4
5
values of $3FF ($FF in 8-bit mode) for analog inputs greater than VRH and $000 for values less
than VRL unless the current is higher than specified as disruptive conditions.
current is picked up by the channel (coupling ratio K), This additional current impacts the accuracy
of the conversion depending on the source resistance.
The additional input voltage error on the converted channel can be calculated as V
I
channel.
INJ
, with I
C
C
T
C
C
C
Max input Source Resistance
Total Input Capacitance
Non Sampling
Sampling
Disruptive Analog Input Current
Coupling Ratio positive current injection
Coupling Ratio negative current injection
INJ
being the sum of the currents injected into the two pins adjacent to the converted
Table B-12 ATD Electrical Characteristics
Freescale Semiconductor, Inc.
For More Information On This Product,
Rating
Go to: www.freescale.com
f
≥ 1024 * (C
Device User Guide — 9S12E128DGV1/D V01.04
Symbol
C
C
I
R
K
K
NA
INS
INN
INS
S
p
n
- C
INN
Min
-2.5
).
-
Typ
-
ERR
Max
10
10
2.5
10
15
1
-4
-2
= K * R
Unit
A/A
A/A
KΩ
mA
pF
S
141
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