MCF5485 FREESCALE [Freescale Semiconductor, Inc], MCF5485 Datasheet - Page 9

• Manufacturer Part Number: MCF5485
• Description: Integrated Microprocessor Electrical Characteristics
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

4.4
To minimize noise, an external filter is required for each of the USB power pins. The filter shown in
connected between the board EV
Table 5
Freescale Semiconductor
•
•
•
•
•
•
lists the resistor values and supply voltages to be used in the circuit for each of the USB V
The resistor and capacitors should be placed as close to the dedicated USB V
A separate filter circuit should be included for each USB V
All traces should be as low impedance as possible, especially ground pins to the ground plane.
The filter for USB_PHYVDD to VSS should be connected to the power and ground planes, respectively, not fingers
of the planes.
In addition to keeping the filter components for the USB_PLLVDD as close as practical to the body of the processor
as previously mentioned, special care should be taken to avoid coupling switching power supply noise or digital
switching noise onto the portion of that supply between the filter and the processor.
The capacitors for C2 in the table below should be rated X5R or better due to temperature performance.
USB Power Filtering
In addition to the above filter circuitry, a 0.01 F capacitor is also recommended in parallel
with those shown.
(Oscillator analog supply)
(Main transceiver supply)
(Bias generator supply)
(Oscillator supply)
USB_OSCAVDD
Board EV
USB_OSCVDD
USB_PHYVDD
USB_PLLVDD
USB V
(PLL supply)
MCF5485 Integrated Microprocessor Electrical Characteristics, Rev. 3
USBVDD
DD
DD
DD
Pin
/IV
or IV
DD
DD
Table 5. USB Filter Circuit Values
Figure 6. USB V
and each of the USB V
R1
Nominal Voltage
3.3V
3.3V
1.5V
3.3V
1.5V
NOTE
C1
GND
DD
Power Filter
DD
DD
pin, a total of five circuits.
pins.
R1 (Ω)
C2
10
10
0
0
0
DD
C1 (μF)
pin as possible.
USB V
Hardware Design Considerations
10
10
10
10
1
DD
DD
Pin
Figure 6
pins.
C2 (μF)
0.1
0.1
0.1
0.1
0.1
should be
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