MC9S12E256 Datasheet, PDF (587/602 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

Appendix A Electrical Characteristics
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.
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
2
T Total Input Capacitance
Non Sampling
Sampling
3
C Disruptive Analog Input Current
4
C Coupling Ratio positive current injection
5
C Coupling Ratio negative current injection
R_S
C_INN
C_INS
I_NA
K_p
K_n
—
—
—
—
—
—
–2.5
—
—
—
—
—
1
KΩ
pF
10
15
2.5
mA
10^-4
A/A
10^-2
A/A
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-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
2 P 10-Bit Differential Nonlinearity
DNL
–1
—
3 P 10-Bit Integral Nonlinearity
4 P 10-Bit Absolute Error¹
INL
–2.0
—
AE
–2.5
—
5 C 10-Bit Absolute Error at f_ATDCLK= 4MHz
6 P 8-Bit Resolution
AE
—
±7.0
LSB
—
20
7 P 8-Bit Differential Nonlinearity
DNL
–0.5
—
8 P 8-Bit Integral Nonlinearity
INL
–1.0
±0.5
9 P 8-Bit Absolute Error¹
AE
–1.5
±1.0
1 _{These values include quantization error which is inherently 1/2 count for any A/D converter.}
—
mV
1
Counts
2.0
Counts
2.5
Counts
—
Counts
—
mV
0.5
Counts
1.0
Counts
1.5
Counts
MC9S12E256 Data Sheet, Rev. 1.08
Freescale Semiconductor
587