Freescale Semiconductor MPC5553, Reference Manual

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MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
Freescale Semiconductor 19-93
Table 19-51 shows the channel number assignments for the non-multiplexed mode. The 40 single-ended
channels and 4 differential pairs are shared between the two ADCs.
Figure 19-52 shows the channel number assignments for multiplexed mode. The ADC with the
ADC n _EMUX bit asserted can access 4 differential pairs, 39 single-ended, and, at most, 32 externally
multiplexed channels. Refer to Section 19.4.6.2, “External Multiplexing ,” for a detailed explanation about
how external multiplexing can be achieved.
Table 19-50. ADCn_EMUX Bits Combinations
ADC0_EMUX ADC1_EMUX
CHANNEL_NUMBER should be set as in
ADC0 ADC1
0 0 Refer to Table 19-51 Refer to Table 19-51
0 1 Refer to Table 19-51 Refer to Figure 19-52
1 0 Refer to Figure 19-52 Refer to Table 19-51
1 1 Reserved
1
1
ADC0_EMUX and ADC1_EMUX must not be asserted at the same time.
Table 19-51. Non-multiplexed Channel Assignments
1
1
The two on-chip ADCs can access the same analog input pins but simultaneous conversions are not allowed. Also, when
one ADC is performing a differential conversion on a pair of pins, the other ADC must not access either of these two pins
as single-ended channels.
Input Pins
Channel Number in
CHANNEL_NUMBER Field
Analog
Pin Name
Other
Functions
Conversion Type Binary Decimal
AN0 to AN39 Single-ended 0000_0000 to 0010_0111 0 to 39
VRH Single-ended 0010_1000 40
VRL Single-ended 0010_1001 41
(VRH - VRL)/2
see footnote
2
2
This equation only applies before calibration. After calibration, the 50% reference point will actually return approximately
20mV lower than the expected 50% of the difference between the High Reference Voltage (VRH) and the Low Reference
Voltage (VRL). For calibration of the ADC only the 25% and 75% points should be used as described in
Section 19.5.6.1,
“MAC Configuration Procedure ”
Single-ended 0010_1010 42
75% x (VRH - VRL) Single-ended 0010_1011 43
25% x (VRH - VRL) Single-ended 0010_1100 44
Reserved 0010_1101 to 0101_1111 45 to 95
DAN0+ and DAN0-
DAN1+ and DAN1-
DAN2+ and DAN2-
DAN3+ and DAN3- Differential
Differential
Differential
Differential 0110_0000
0110_0001
0110_0010
0110_0011 96
97
98
99
Reserved 0110_0100 to 1111_1111 100 to 255