MC9S12KG128_10 Datasheet, PDF (581/606 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

Appendix A Electrical Characteristics
A.5.2.3 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 VRH and $000 for values less
than VRL 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.
Table A-13. ATD Electrical Characteristics
Conditions are shown in Table A-4 unless otherwise noted
Num
Rating
Symbol
Min
Typ
Max
Unit
1 Max input Source Resistance
R_S
—
—
1
KΩ
2 Total Input Capacitance
pF
Non Sampling C_INN
—
—
10
Sampling C_INS
—
—
22
3 Disruptive Analog Input Current
4 Coupling Ratio positive current injection
5 Coupling Ratio negative current injection
I_NA
–2.5
—
2.5
mA
K_p
—
—
10^-4
A/A
K_n
—
—
10^-2
A/A
A.5.3 ATD Accuracy
Table A-14 and Table A-15 specify the ATD conversion performance excluding any errors due to current
injection, input capacitance and source resistance.
Table A-14. 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 = 5m. Vf_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
–2.5
±1.5
AE
–3
±2.0
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
9 P 8-Bit Absolute Error¹
INL
–1.0
±0.5
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
2.5
Counts
3
Counts
—
Counts
—
mV
0.5
Counts
1.0
Counts
1.5
Counts
MC9S12KG128 Data Sheet, Rev. 1.16
Freescale Semiconductor
581