MC9S12Q128_10 Datasheet, PDF (612/644 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

Appendix A Electrical Characteristics
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.
Table 20-18. 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
Total Input Capacitance
2
T
Non Sampling
Sampling
C_INN
C_INS
3
C Disruptive Analog Input Current
I_NA
4
C ^{Coupling Ratio positive current injection}
K_p
5
C ^{Coupling Ratio negative current injection}
K_n
—
—
1
KΩ
—
—
10
pF
—
—
15
–2.5
—
2.5
mA
—
—
10^-4
A/A
—
—
10^-2
A/A
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 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
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 Error⁽¹⁾
INL
–2
—
AE
-2.5
—
5
P 8-Bit Resolution
LSB
—
20
6
P 8-Bit Differential Nonlinearity
DNL
–0.5
—
7
P 8-Bit Integral Nonlinearity
INL
–1.0
±0.5
8
P 8-Bit Absolute Error¹
AE
-1.5
±1
1. These values include quantization error which is inherently 1/2 count for any A/D converter.
Max
Unit
—
mV
1
Counts
2
Counts
2.5
Counts
—
mV
0.5
Counts
1.0
Counts
1.5
Counts
612
MC9S12Q128
Freescale Semiconductor
Rev 1.10