MPC564EVB Freescale Semiconductor, MPC564EVB Datasheet - Page 533

• Manufacturer Part Number: MPC564EVB
• Description: KIT EVAL FOR MPC561/562/563/564
• Manufacturer: Freescale Semiconductor
• Type: Microcontrollerr

Specifications of MPC564EVB

• Contents: Module Board, Installation Guide, Power Supply, Cable, Software and more
• Processor To Be Evaluated: MPC56x
• Data Bus Width: 32 bit
• Interface Type: RS-232, Ethernet
• For Use With/related Products: MPC561, 562, 563, 564
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

13.7.3.1
Two important factors influencing performance in analog integrated circuits are supply filtering and
grounding. Generally, digital circuits use bypass capacitors on every VDD/VSS signal pair. This applies
to analog sub-modules also. The distribution of power and ground is equally important.
Analog supplies should be isolated from digital supplies as much as possible. This necessity stems from
the higher performance requirements often associated with analog circuits. Therefore, deriving an analog
supply from a local digital supply is not recommended. However, if for economic reasons digital and
analog power are derived from a common regulator, filtering of the analog power is recommended in
addition to the bypassing of the supplies already mentioned.
For example, an RC low pass filter could be used to isolate the digital and analog supplies when generated
by a common regulator. If multiple high precision analog circuits are locally employed (i.e., two A/D
converters), the analog supplies should be isolated from each other as sharing supplies introduces the
potential for interference between analog circuits.
Grounding is the most important factor influencing analog circuit performance in mixed signal systems (or
in stand-alone analog systems). Care must be taken to not introduce additional sources of noise into the
analog circuitry. Common sources of noise include ground loops, inductive coupling, and combining
digital and analog grounds together inappropriately.
Freescale Semiconductor
Analog Supply Filtering and Grounding
3FE
3FD
3FC
3FB
3FA
3FF
8
7
6
5
4
3
2
1
0
.010
Figure 13-50. Errors Resulting from Clipping
MPC561/MPC563 Reference Manual, Rev. 1.2
.020
Input in Volts (V RH = 5.120,
.030
5.100
5.110
V
RL
= 0 V)
5.120
5.130
QADC64E Legacy Mode Operation
QADC64E CLIPPING
13-69