
MOTOROLA
Appendix C. Clock and Board Guidelines
C-3
MPC56x Device Power Distribution
Figure C-2. Power Distribution Diagram — 5 V and Analog
VDDH (digital 5 V)
VDDA
VSSA
VRH
VRL
ANx (Analog Input)
Keyed
VDD 5 V
100 nF
1uF
1nF
~10k
<10
<10
To
From
Sensors
100 nF
~10 nF
R23
Sensors
100 nF
Analog
ground
plane
ALTREF
100 nF
VFLASH
1. 10 ohms is recommended because IREF (max) is 250 A per QADC64. 10 Ohm x 2 modules x 250 A
= 5 mV (approximately one count, or one LSB)
2. The QADC64 circuit design allows for VDDA being less than VRH with a value of up to 10 ohms in this
RC filter.
3. This size of resistor R2 depends on the sensor load current. It should be sized to match the voltage at
VRH.
Board
MPC56x Device
1, 2