N900 Hardware Power management

The power managment on the N900 is very complex, and involves a large number of interacting systems.


[edit] Hardware

[edit] SoC

The System-on-a-chip is the main processor on the n900. This is the TI omap3430. For more information see N900 CPU.

[edit] Gaia

The TWL4030 is a TI companion chip to the SoC. For more information see N900 Hardware Chipset

[edit] USB battery charger

The bq24150a charger from TI is a flexible charger. It, along with the PHY chip - support charging without the intervention of the SoC when the system is charging from a completely dead battery. The PHY chip detects a charger (shorted D+ and D- pins) and the charger uses this information to charge more rapidly.

It also features reverse boost mode - which enables power to be supplied to a USB device connected to the N900. (up to a limit of 200 mA)

For more information see N900 Hardware Battery Charger

[edit] Firmware

The CPU is designed to work intimately with the companion chip, in order to implement SmartReflex.

This TIs method of adjusting the voltage of various portions of the chip dynamically, in order to ensure the power delivered to the many separate sections of the chip is just sufficient to allow for the current needs.

All parts of the CPU that are not immediately in use are powered down.

The CPU has well over a dozen seperate functional blocks, each of which can be powered on/off seperately.

This dramatically reduces power usage.

[edit] Software

Main article: N900 software power management