Windows power and battery subsystem requirements

To meet user expectations and provide a quality experience, all Windows PCs must have consistent behavior for battery charging and system power transitions. Starting with Windows 8 and Windows 8.1, this design principle extends to battery-powered hardware platforms that are based on System on a Chip (SoC) integrated circuits and that support the connected standby power model.

This section describes the user experience requirements for the power and battery charging subsystem in a hardware platform that runs Windows. It provides detailed implementation guidance for platform designers and firmware developers. They can use this information to ensure their platforms are compatible with Windows power management software.

The information in this section pertains to all processor architectures—x86, x64, and ARM—that are supported by Windows. In addition, this information applies both to low-power platforms that implement the connected standby power model and to platforms that support the traditional ACPI sleep (S3) and hibernate (S4) power states.

In this section

TopicDescription

User experience principles for battery charging

Users expect to have a consistent and quality experience around battery charging. Therefore, all systems in the Windows ecosystem must have a consistent battery charging experience, regardless of form factor, instruction set, or platform architecture.

Power and charging subsystem implementation

The battery power and charging subsystem in a Windows platform should implement the ACPI Control Method Battery interface. Windows uses this interface to get status information from the battery subsystem and to receive notifications of battery events.

ACPI battery and power subsystem firmware implementation

Windows platforms are expected to expose their battery devices and AC adapters in firmware through ACPI by using standardized control method interfaces, as described in the ACPI 5.0 specification.

Battery and power subsystem hardware design

Starting with Windows 8, system hardware designers can choose between two different hardware topologies for the battery and power subsystems in their Windows platforms.

Platform requirements and motivation

The Windows hardware requirements for the power and battery subsystem are motivated by the need to meet user expectations and to provide fault-tolerant platform operation.

Power and battery subsystem checklist

System designers can use the checklists included in this section to verify that their platform designs and system firmware follow the Windows guidelines for power and battery subsystem operation. Each item in a checklist specifies whether the requirement applies to PCs that implement the traditional ACPI S3 and S4 power states, and/or to PCs that implement the connected standby power model.

USB charging

Starting with Windows 8, a mobile Windows PC can be designed to be powered and/or charged by a USB charger. The same charger can be used to charge other devices, such as Windows phones, MP3 players, and GPS devices.

Automated lab testing considerations

We recommend that system designers consider automated lab testing scenarios when they design the power and battery charging subsystem. The most relevant consideration is platform recovery from crash or hang scenarios.

 

 

 

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