MPC564EVB Freescale Semiconductor, MPC564EVB Datasheet - Page 535

• 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

13.7.4
V
reference inputs from the power supply signals allows for additional external filtering, which increases
reference voltage precision and stability, and subsequently contributes to a higher degree of conversion
accuracy.
No A/D converter can be more accurate than its analog reference. Any noise in the reference can result in
at least that much error in a conversion. The reference for the QADC64E, supplied by signals V
V
capacitive bypassing may sufficed. In extreme cases, inductors or ferrite beads may be necessary if noise
or RF energy is present. Series resistance is not advisable since there is an effective DC current
requirement from the reference voltage by the internal resistor string in the RC DAC array. External
resistance may introduce error in this architecture under certain conditions. Any series devices in the filter
network should contain a minimum amount of DC resistance.
13.7.5
Analog inputs should have low AC impedance at the signals. Low AC impedance can be realized by
placing a capacitor with good high frequency characteristics at the input signal of the part. Ideally, that
capacitor should be as large as possible (within the practical range of capacitors that still have good high
frequency characteristics). This capacitor has two effects:
Freescale Semiconductor
RH
RL
•
, should be low-pass filtered from its source to obtain a noise-free, clean signal. In many cases, simple
and V
It helps attenuate any noise that may exist on the input.
PCB
RL
Analog Reference Signals
Analog Input Signals
are the dedicated input signals for the high and low reference voltages. Separating the
+5V
Figure 13-51. Star-Ground at the Point of Power Supply Origin
Analog Power Supply
AGND
QADC64E
MPC561/MPC563 Reference Manual, Rev. 1.2
+5V
VDD
VSS
PGND
Digital Power
QADC64E Legacy Mode Operation
Supply
+5V
RH
, and
13-71