
Queued Analog-to-Digital Converter (QADC)
Signals
MMC2114 MMC2113 MMC2112 — Rev. 1.0
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MOTOROLA
Queued Analog-to-Digital Converter (QADC)
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19.6.5 Multiplexed Analog Input Pins
In external multiplexed mode, four of the port QB pins are redefined to
each represent four analog input channels. See
Table 19-1
.
19.6.6 Voltage Reference Pins
V
RH
and V
RL
are the dedicated input pins for the high and low reference
voltages. Separating the reference inputs from the power supply pins
allows for additional external filtering, which increases reference voltage
precision and stability, and subsequently contributes to a higher degree
of conversion accuracy.
NOTE:
V
RH
and V
RL
must be set to V
DDA
and V
SSA
potential, respectively.
19.6.7 Dedicated Analog Supply Pins
The V
DDA
and V
SSA
pins supply power to the analog subsystems of the
QADC module. Dedicated power is required to isolate the sensitive
analog circuitry from the normal levels of noise present on the digital
power supply.
19.6.8 Dedicated Digital I/O Port Supply Pin
V
DDH
provides 5-V power to the digital I/O functions of QADC port QA
and port QB. This allows those pins to tolerate 5 volts when configured
as inputs and drive 5 volts when configured as outputs.
Table 19-1. Multiplexed Analog Input Channels
Multiplexed
Analog Input
Channels
ANw
Even numbered channels from 0 to 6
ANx
Odd numbered channels from 1 to 7
ANy
Even numbered channels from 16 to 22
ANz
Odd numbered channels from 17 to 23
F
Freescale Semiconductor, Inc.
n
.