MC9S12E32CFU FREESCALE [Freescale Semiconductor, Inc], MC9S12E32CFU Datasheet - Page 591

• Manufacturer Part Number: MC9S12E32CFU
• Description: HCS12 Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

A.6.3.2
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
A.6.3.3
There are two cases to consider.
Freescale Semiconductor
Conditions are shown in
Num
1
2
3
4
5
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
values of 0x3FF (0xFF in 8-bit mode) for analog inputs greater than VRH and 0x000 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
to the converted channel.
ERR
C
C
C
C
C
T
Source Capacitance
Current Injection
= K * R
Max input Source Resistance
Total Input Capacitance
Disruptive Analog Input Current
Coupling Ratio positive current injection
Coupling Ratio negative current injection
Non Sampling
Sampling
Table A-4
S
* I
INJ
, with I
unless otherwise noted
Table A-21. ATD Electrical Characteristics
Rating
INJ
MC9S12E128 Data Sheet, Rev. 1.07
being the sum of the currents injected into the two pins adjacent
f
1024 * (C
Symbol
C
C
I
R
INS
K
K
NA
INN
INS
S
p
n
- C
INN
–2.5
Min
).
—
—
—
—
—
Appendix A Electrical Characteristics
Typ
—
—
—
—
—
—
Max
10
10
2.5
10
15
1
-4
-2
Unit
A/A
A/A
K
mA
pF
591