XO 1.75 Power Distribution
This page describes the power distribution network of the XO-1.75 laptop, specifically the production C2 version.
Contents
Introduction
Inside a laptop, power has to be distributed from the battery to the different laptop components and efficiently transformed to suitable voltages. Low power is one of our highest design goals, and an efficient power distribution network is essential.
In the majority of places where we need to provide a particular voltage, a switching voltage regulator is used which efficiently transforms 85 - 90% of the power. In a few low power situations, small linear regulators are used --- these dissipate any excess voltage as waste heat.
Battery Technology
The battery technology used in the XO-1.75 is the same Lithium Ferro-Phosphate (LiFePO4) used in all XO laptops. It is similar to the more common Li-Ion battery, but safer. For power efficiency reasons, we use two cells in series. This provides a battery with an operating voltage (+VBAT in the diagram) of 5.4 to 7.4V.
DC Power Input
Armada 610
Embedded Controller
Power Distribution
The following diagram attempts to illustrate the power distribution network:
