Intel® 31244 PCI-X to Serial ATA Controller
Voltage Power Delivery
Voltage Power Delivery | 9 |
There are two different voltages needed on the Intel® 31244
9.1Intel® 31244
In most system board designs, the 3.3 V system power supply is routed to board components through a dedicated board layer. With the requirements for 2.5 V supplies for the GD31244, it is not necessary to add completely new power supply layers to the circuit board to facilitate this. It is possible to create supply “islands” underneath GD31244 in the existing power supply plane.
Other important considerations are:
•Τhe ‘island’ must be large enough to include the required power supply decoupling capacitance, and the necessary connection to the voltage source.
•Τo minimize signal degradation, the gap between the supply island and the voltage plane kept to a minimum: typical gap size is about 0.02 inches.
•Minimize the number of traces routed across the power plane gap, since each crossing introduces signal degradation due to the impedance discontinuity that occurs at the gap. For traces that must cross the gap, route them on the side of the board next to the ground plane to reduce or eliminate the signal degradation caused by crossing the gap. When this is not possible, then route the trace to cross the gap at a right angle (90 degrees).
•Use liberal decoupling capacitance between the voltage plane and the supply islands. Decoupling the island reduces impedance discontinuity.
Design Guide | 59 |
