Datasheet
Appendix A Electrical Characteristics
660 MC9S12C-Family / MC9S12GC-Family Freescale Semiconductor
Rev 01.24
A.2.3.3 Current Injection
There are two cases to consider.
1. A current is injected into the channel being converted. The channel being stressed has conversion
values of $3FF ($FF in 8-bit mode) for analog inputs greater than V
RH
and $000 for values less
than V
RL
unless the current is higher than specified as disruptive conditions.
2. Current is injected into pins in the neighborhood of the channel being converted. A portion of this
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
ERR
=K*R
S
*
I
INJ
, with I
INJ
being the sum of the currents injected into the two pins adjacent to the converted
channel.
A.2.4 ATD Accuracy (5V Range)
Table A-12 specifies the ATD conversion performance excluding any errors due to current injection, input
capacitance and source resistance
.
Table 21-18. ATD Electrical Characteristics
Conditions are shown in Table A-4 unless otherwise noted
Num C Rating Symbol Min Typ Max Unit
1C
Max input Source Resistance R
S
—— 1KΩ
2T
Total Input Capacitance
Non Sampling
Sampling
C
INN
C
INS
—
—
—
—
10
15
pF
3C
Disruptive Analog Input Current I
NA
–2.5 — 2.5 mA
4C
Coupling Ratio positive current injection
K
p
——
10
-4
A/A
5C
Coupling Ratio negative current injection
K
n
——
10
-2
A/A
Table A-12. ATD Conversion Performance
Conditions are shown in Table A-4 unless otherwise noted
V
REF
= V
RH
– V
RL
= 5.12V. Resulting to one 8 bit count = 20mV and one 10 bit count = 5mV
f
ATDCLK
= 2.0MHz
Num C Rating Symbol Min Typ Max Unit
1 P 10-Bit Resolution LSB — 5 — mV
2 P 10-Bit Differential Nonlinearity DNL –1 — 1 Counts
3 P 10-Bit Integral Nonlinearity INL –2 — 2 Counts
4 P 10-Bit Absolute Error
(1)
1. These values include quantization error which is inherently 1/2 count for any A/D converter.
AE -2.5 — 2.5 Counts
5 P 8-Bit Resolution LSB — 20 — mV
6 P 8-Bit Differential Nonlinearity DNL –0.5 — 0.5 Counts
7 P 8-Bit Integral Nonlinearity INL –1.0 ±0.5 1.0 Counts
8 P 8-Bit Absolute Error
1
AE -1.5 ±1 1.5 Counts