Datasheet

Appendix A Electrical Characteristics
MC9S12E256 Data Sheet, Rev. 1.10
Freescale Semiconductor 599
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.6.4 ATD Accuracy — 5V Range
Table A-22 specifies the ATD conversion performance excluding any errors due to current injection, input
capacitance and source resistance.
Table A-21. ATD Electrical Characteristics
Conditions are shown in Table A-4 unless otherwise noted
Num C Rating Symbol Min Typ Max Unit
1 C Max input Source Resistance R
S
—— 1 KΩ
2 T Total Input Capacitance
Non Sampling
Sampling
C
INN
C
INS
—
—
—
—
10
15
pF
3 C Disruptive Analog Input Current I
NA
–2.5 — 2.5 mA
4 C Coupling Ratio positive current injection K
p
——10
-4
A/A
5 C Coupling Ratio negative current injection K
n
——10
-2
A/A
Table A-22. 5V 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 –2.5 — 2.5 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 C 10-Bit Absolute Error at f
ATDCLK
= 4MHz AE — ±7.0 — Counts
6 P 8-Bit Resolution LSB — 20 — mV
7 P 8-Bit Differential Nonlinearity DNL –0.5 — 0.5 Counts
8 P 8-Bit Integral Nonlinearity INL –1.0 ±0.5 1.0 Counts
9 P 8-Bit Absolute Error
1
AE –1.5 ±1.0 1.5 Counts