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P5040/P5020 Reference Design Board User Guide, Rev. 0
Freescale Semiconductor
33
Architecture
NOTE
ASLEEP negation indicates the processor has exited reset. ASLEEP
assertion does not cause reset because, following HRST, the processor can
“sleep” for multiple reasons.
Drivers can be driven following power up. Normal operation and/or use of the VELA engine can lead to
tri-stated IOs. During power-off, all IO and output drivers must be tri-stated.
5.3
System Power Connections
The 12-V, 5-V, and 3.3-V power requirements for the reference board are met by the attached 1U-12V
compatible power supply unit (PSU) of the P5040/P5020RDB. The 5 V and 3.3 V are connected to
individual power planes in the P5040/P5020RDB PCB stackup. The 12-V power from the standard 1U
header is treated as separate from the 1U-12V power, which supplies a large amount of current and is
referred to as VCC_12V_BULK. Other supplies include VCC_5VSTBY and VCC_BAT.
Note that to support the FPGA standby operation, video cards, or other high-power-dissipation cards in the
PCI Express slot, the PSU should support the following minimum specifications:
•
Minimum 450 W overall, 500 W recommended
•
PCIE 12 V supports a minimum of 150 W
•
Minimum 5-V, 2-A standby current
All other power sources are also derived from the 1U PSU. The figure below shows the principal system
power connections in relation to the FPGA control. For details about the processor power scheme
implemented by this system, see the Power device feature row in