If a PCI expansion card requiring 3.3V is installed, that voltage can be connected to
Switching Power Supplies
If you use a switching power supply, be sure it regulates properly with the load your system draws. Some switching power supplies do not regulate properly unless they are loaded to some minimum value. If this is the case with your supply, consult the manufacturer about additional loading, or use another supply or another type of power source (such as a linear supply, batteries, etc.). The minimum power for the Little Board P6d system appears in the power specifications in Chapter 1.
Powerfail NMI
The Little Board P6d module includes a circuit that can sense a power failure. If the +5V power supply falls below ~4.7V, the powerfail logic produces a
When a NMI occurs, the BIOS detects the NMI and displays the message “Power Fail NMI” on the console. At this point you have two options via the keyboard. You can mask the NMI and continue (the PC architecture provides a mask bit for the
If you want your system to respond to the NMI, you can provide a NMI handler in your application, and patch the NMI interrupt vector address to point to your routine.
Backup Battery
The
Cooling Requirements
The
A heat sink and fan are provided for the CPU and a thermal sensor is used to monitor the CPU temperature, as described below.
Thermal Sensor
A thermal sensor monitors the internal temperature of the