3.4. Power supply

The power supply circuit is shown in Figure 3.16.

If the baseboard is powered from the 12V brick power supply:

If the baseboard is powered from the PCI backplane or the screw terminals, the VSMP and DC fused voltages are not present. Therefore:

Caution

There is no overvoltage or polarity protection if the PCI backplane or screw terminals are used as the power source. Connecting an incorrect voltage to the screw terminals might damage the baseboard and any boards connected to it.

The 12V DCIN supply is fused (5A) before connection to the polarity and shutdown logic. The LCD expansion, USB, Keyboard, and Mouse connectors have an additional fuse (1A) on the 5V supply.

Warning

Refer to the Bill of Materials (BOM) file in the schematics directory for the fuse manufacturer and part numbers. You must use the same type and rating of fuse if you replace a blown fuse.

There are also two regulators for the USB debug circuit. These are powered from the 5V supplied by the host computer on the USB connector. See JTAG and USB debug port support.

Logic Tiles supply the correct interface voltage for memory or peripherals by driving the VDDIO power pins on the HDRX and HDRY Logic Tile connectors. If a tile is not present on a tile site:

Figure 3.16. Power-supply regulators and protection circuitry

To view this graphic, your browser must support the SVG format. Either install a browser with native support, or install an appropriate plugin such as Adobe SVG Viewer.


Figure 3.17. Reverse-polarity protection and shutdown circuit

Reverse-polarity protection and shutdown circuit

Copyright © 2005-2011 ARM Limited. All rights reserved.ARM DUI 0411D
Non-Confidential