Connected Standby

Purpose

Starting with Windows 8 and Windows 8.1, PCs that implement the connected standby power model run at very low power levels, but stay connected and up-to-date, even when they appear to the user to be turned off.

Connected standby is not an isolated feature that can be added to the design of a Windows PC as an afterthought. The decision to support connected standby must be made at the start of the design process because it governs the selection of every hardware and software component.

In this section

TopicDescription

Introduction to connected standby

The connected standby power model enables Windows PCs to provide an instant-on, always-connected experience, similar to that of smartphone devices. The underlying power-management technologies that support connected standby are dramatically different from what's required to support the traditional ACPI Sleep (S3) and Hibernate (S4) states.

Connected standby wake sources

A PC that supports the connected standby power model must be capable of waking from connected standby in response to certain events, even if the platform has entered a very low-power idle state.

Validating connected standby

Enabling the low power consumption and constant connectivity of connected standby is a test and validation challenge for the system integrator. All components in the system—hardware and software—must work together to quickly turn power on and off while maintaining connection to the Internet.

Windows ACPI design guide for SoC platforms

The Advanced Configuration and Power Interface Specification, Revision 5.0 (ACPI 5.0 specification), defines a new set of features to support low-power, mobile PCs that are based on System on a Chip (SoC) integrated circuits and that implement the connected standby power model. Starting with Windows 8 and Windows 8.1, Windows supports the new ACPI 5.0 features for SoC-based platforms.

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 SoC integrated circuits and that support the connected standby power model.

Device-specific power management for connected standby

To achieve long battery life in connected standby, a platform must be able to operate at a very low hardware power floor. The term power floor describes the hardware power state in which all devices are idle and inactive, and power consumption is dominated by hardware static leakage. If properly designed, the platform typically spends well over 90 percent of a connected standby session operating at the platform's power floor.

Thermal management in Windows

Thermal management plays a key role in delivering PCs that have good performance and are safe to use—even when they are running a high-energy workload. PCs are becoming more mobile and compact, making hardware design for thermal dissipation more challenging. At the same time, users' expectations for performance and capabilities continue to grow, increasing the heat generation of system components. Good thermal design is now more important than ever.

 

Developer audience

This section contains detailed guidance for developers of hardware platforms that run Windows and that implement the connected standby power model.

 

 

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