MMCCMB2107 Freescale, MMCCMB2107 Datasheet - Page 499

• Manufacturer Part Number: MMCCMB2107
• Manufacturer: Freescale

Specifications of MMCCMB2107

• Lead Free Status / RoHS Status: Not Compliant

18.11.7.2 Error Resulting from Leakage
MMC2107 – Rev. 2.0
MOTOROLA
CAUTION:
The external circuit described in
interested in measuring an ac component of the external signal must
take the characteristics of this filter into account.
A series resistor limits the current to a pin therefore, input leakage acting
through a large source impedance can degrade A/D accuracy. The
maximum input leakage current is specified in
Specifications. Input leakage is greater at higher operating
temperatures. In the temperature range from 125°C to 50°C, the leakage
current is halved for every 8°C to 12°C reduction in temperature.
Assuming V
corresponds to 5 mV of input voltage. A typical input leakage of 200 nA
acting through 10 k of external series resistance results in an error of
0.4 count (2.0 mV). If the source impedance is 100 k
leakage of 100 nA is present, an error of 2 counts (10 mV) is introduced.
In addition to internal junction leakage, external leakage (for example, if
external clamping diodes are used) and charge sharing effects with
internal capacitors also contribute to the total leakage current.
Table 18-17
accuracy for different values of source impedance. The error is listed in
terms of 10-bit counts.
Leakage from the part below 200 nA is obtainable only within a limited
temperature range.
Freescale Semiconductor, Inc.
For More Information On This Product,
Queued Analog-to-Digital Converter (QADC)
Filter Capacitor (C
Table 18-16. External Circuit Settling Time to 1/2 LSB
0.001 F
0.01 F
100 pF
0.1 F
RH
1 F
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illustrates the effect of different levels of total leakage on
–V
RL
= 5.12 V, 1 count (with 10-bit resolution)
F
)
(10-Bit Conversions)
760 s
760 ns
100
7.6 s
76 s
76 ns
Table 18-16
Queued Analog-to-Digital Converter (QADC)
Source Resistance (R
760 s
7.6 ms
760 ns
7.6 s
76 s
1 k
is a low-pass filter. A user
Pin Connection Considerations
Section 22. Electrical
760 s
7.6 ms
10 k
76 ms
7.6 s
76 s
and a typical
F
+ R
Technical Data
SRC
100 k
760 ms
7.6 ms
760 s
)
76 ms
76 s
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