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Enhanced Queued Analog-to-Digital Converter (EQADC)
MPC5644A Microcontroller Reference Manual, Rev. 6
1134
Freescale Semiconductor
Figure 25-82. Overlapping Consecutive Conversion Commands
25.6.7
Internal/External Multiplexing
25.6.7.1
Channel assignment
The internal analog multiplexers select one of the 40 analog input pins for conversion, based on the
CHANNEL_NUMBER field of a Command Message. The analog input pin channel number assignments
and the pin definitions vary depending on how the ADC0/1_EMUX are configured. Allowed combinations
of ADC0/1_EMUX bits are shown in
together with references to tables indicating how
CHANNEL_NUMBER field of each conversion command must be set to avoid channel selection
conflicts.
During differential conversions the analog multiplexer passes differential signals to both the positive and
negative terminals of the ADC. The differential conversions can only be initiated on four channels: DAN0,
Channel # Change
and Sample Start
(a) Command Execution Sequence for Two Non-Overlapped Commands
(b) Command Execution Sequence for Two Overlapped Commands
Minimum time necessary to perform a single
conversion after channel number is changed
Channel # Change
and Sample Start
AD Conversion
MUX Settle Time
and Sampling
AD Conversion
MUX Settle Time
and Sampling
Conversion starts immediately after channel #
change.ADC sample time should compensate
for MUX internal capacitance settling and for the
sampling on the sampling capacitor. If sample
time is not long enough, this can lead to
inaccurate conversion results.
AD Conversion
Change
Channel #
MUX Settle Time
and Sampling
Channel # Change
and Sample Start
AD Conversion
Sampling
Sample Start
Channel # changes before sampling starts leading to
more time for MUX internal capacitance to settle.
MUX Settle Time
Summary of Contents for MPC5644A
Page 2: ...MPC5644A Microcontroller Reference Manual Rev 6 2 Freescale Semiconductor...
Page 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Page 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Page 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Page 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Page 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Page 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...