PCX745BVZFU350LE Atmel, PCX745BVZFU350LE Datasheet - Page 41

• Manufacturer Part Number: PCX745BVZFU350LE
• Description: IC MPU 32BIT 350MHZ 255PBGA
• Manufacturer: Atmel

Specifications of PCX745BVZFU350LE

• Processor Type: PowerPC 32-Bit RISC
• Speed: 350MHz
• Voltage: 2V
• Mounting Type: Surface Mount
• Package / Case: 255-PBGA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -

10. System Design Information
10.1
10.2
2138G–HIREL–05/06
PLL Power Supply Filtering
Power Supply Voltage Sequencing
The AV
generation phase-locked loop and L2 cache delay-locked loop respectively. To ensure stability
of the internal clock, the power supplied to the AV
the 500 kHz to 10 MHz resonant frequency range of the PLL. A circuit similar to the one shown
in
is recommended. Consistent with the recommendations of Dr. Howard Johnson in High Speed
Digital Design: A Handbook of Black Magic (Prentice Hall, 1993), multiple small capacitors of
equal value are recommended over a single large value capacitor.
The circuit should be placed as close as possible to the AV
nearby circuits. An identical but separate circuit should be placed as close as possible to the
L2AV
the periphery of the 360 BGA footprint, without the inductance of vias. The L2AV
more difficult to route but is proportionately less critical.
Figure 10-1. PLL Power Supply Filter Circuit
The notes in
voltages and core voltage of the PC755 (when they are different). These cautions are necessary
for the long term reliability of the part. If they are violated, the ESD (Electrostatic Discharge) pro-
tection diodes will be forward biased and excessive current can flow through these diodes. If the
system power supply design does not control the voltage sequencing, the circuit of
can be added to meet these requirements. The MUR420 Schottky diodes of
the maximum potential difference between the external bus and core power supplies on power-
up and the 1N5820 diodes regulate the maximum potential difference on power-down.
Figure 10-2. Example Voltage Sequencing Circuit
Figure 10-2
DD
DD
pin. It is often possible to route directly from the capacitors to the AV
and L2AV
V
DD
Figure 10-3 on page 43
using surface mount capacitors with minimum Effective Series Inductance (ESL)
DD
power signals are provided on the PC755 to provide power to the clock
3.3V
10 Ω
2.2 µF
MURS320
contain cautions about the sequencing of the external bus
GND
1N5820
DD
1N5820
2.2 µF
input signal should be filtered of any noise in
Low ESL Surface Mount Capacitors
MURS320
DD
pin to minimize noise coupled from
AV
DD
2.0V
(or L2AV
PC755/745
Figure 10-3
DD
DD
)
pin, which is on
DD
Figure 10-3
pin may be
control
41