AN1058 Freescale Semiconductor / Motorola, AN1058 Datasheet - Page 13

• Manufacturer Part Number: AN1058
• Description: Reducing A/D Errors in Microcontroller Applications
• Manufacturer: Freescale Semiconductor / Motorola

AN1058
MOTOROLA
top switch is then opened, and the bottom plates are connected to V
Since the charge on the top plate is conserved, its potential goes to – V
which is the initial voltage at the input of the comparator. The
approximation mode (see
most significant bit by raising the bottom plate of the largest capacitor to
the reference voltage, V
voltage divider between two equal capacitances. The output of the
comparator, after each capacitor is switched, determines whether the
bottom plate of that capacitor will remain at V
before the next capacitor is switched. Conversion proceeds in this
manner until all bits have been determined and the result is stored in the
successive-approximation register (SAR).
Freescale Semiconductor, Inc.
For More Information On This Product,
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Go to: www.freescale.com
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Figure 5. ADC Conversion Modes
0
2
1
BIT 1 BIT 0
H
1
. The equivalent circuit is now actually a
SAR
Figure
0
1
(c) Approximation Mode
1
1
5(c)) begins by testing the value of the
(a) Sample Mode
(b) Hold Mode
2
1
1/2
1
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1/2
or be returned to V
A Specific MCU with ADC
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1
1/2
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Application Note
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