MC9S12B128_05 Datasheet, PDF (95/132 Pages) Motorola, Inc – Covers also preliminary MC9S12B64 using MC9S12B128 die

Device User Guide —9S12B128DGV1/D V01.13
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 condition.
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-12 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
Total Input Capacitance
2 T Non Sampling
Sampling
C_INN
C_INS
10
pF
22
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
95