MAC7100 MOTOROLA [Motorola, Inc], MAC7100 Datasheet - Page 24

• Manufacturer Part Number: MAC7100
• Description: MAC7100 Microcontroller Family Hardware Specifications
• Manufacturer: MOTOROLA [Motorola, Inc]

Electrical Characteristics
3.10.1.1 Source Resistance
Due to the input pin leakage current as specified in Table 15 in conjunction with the source resistance there
will be a voltage drop from the signal source to the ATD input. The maximum specified source resistance R
results in an error of less than 1/2 LSB (2.5 mV) at the maximum leakage current. If the device or operating
conditions are less than the worst case, or leakage-induced errors are acceptable, larger values of source
resistance are allowed.
3.10.1.2 Source Capacitance
When sampling, an additional internal capacitor is switched to the input. This can cause a voltage drop due
to charge sharing with the external capacitance and the pin capacitance. For a maximum sampling error of
the input voltage ≤ 1 LSB, then the external filter capacitor must be calculated as, C
3.10.1.3 Current Injection
There are two cases to consider:
24
Conditions are shown in Table 6 unless otherwise noted
Num C
P1
P2
P3
P4
P5
1. A current is injected into the channel being converted. The channel being stressed has conversion
2. Current is injected into pins in the neighborhood of the channel being converted. A portion of this
C Max input Source Resistance
C Disruptive Analog Input Current
C Coupling Ratio positive current injection
C Coupling Ratio negative current injection
T Total Input Capacitance
values of 0x3FF (0xFF in 8-bit mode) for analog inputs greater than V
than V
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
currents injected into the two pins adjacent to the converted channel.
Non Sampling
Sampling
RL
unless the current is higher than specified as disruptive condition.
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
MAC7100 Microcontroller Family Hardware Specifications
Freescale Semiconductor, Inc.
Rating
For More Information On This Product,
Table 26. ATD Electrical Characteristics
Go to: www.freescale.com
ERR
Symbol
C
C
I
R
K
K
NA
INN
INS
S
p
n
= K
×
R
S
–2.5
Min
—
—
—
—
—
×
I
INJ
, with I
RH
Typ
and 0x000 for values less
—
—
—
—
—
—
INJ
f
≥ 1024
being the sum of the
×
TBD
TBD
Max
2.5
10
22
1
(C
MOTOROLA
INS
– C
Unit
A/A
A/A
mA
KΩ
pF
pF
INN
S
).
,