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.

To reliably operate at the power floor requires each device outside the System on a Chip (SoC) to enter very low standby power state when it is unused. The power management methodology and system configuration used to achieve power-floor operation is device-specific. Power to a device might be controlled autonomously by the device, based on commands from software drivers. Or, power to the device might be managed by ACPI firmware that controls power management hardware external to the device.

This section describes the supported power management configurations for devices outside of the SoC (or core silicon) in a Windows platform that implements the connected standby power model. For each class of device, the supported hardware and software power management configurations are described. The driver developer for a device should work closely with the device vendor and system integrator to review platform schematics, device integration, and ACPI firmware.

Note  This documentation describes the power management configurations that Windows supports for device classes that are commonly used in connected standby platforms. This documentation does not introduce Windows Certification requirements or explicitly discuss such requirements.

In this section

TopicDescription

Audio subsystem power management for connected standby platforms

Every Windows PC has an audio subsystem that enables the user to listen to and record high-quality sound in real-time. A hardware platform that supports the connected standby power model is typically built around a SoC integrated circuit that features built-in, low-power audio processing units.

Bluetooth power management for connected standby platforms

A Bluetooth radio device enables short-range RF communication between a PC and an input device, an audio device, or other Bluetooth-attached user peripheral. In a connected standby PC, the driver for a Bluetooth radio should manage this device's power states according to the guidelines presented in this article.

Camera power management for connected standby platforms

The cameras in modern mobile platforms allow users to capture still and motion video of their surroundings, and to use video and audio to communicate with other users over the Internet. The general goal of power management for a camera device can be described simply—the camera subsystem must be powered off, consuming zero watts, unless the camera is in active use.

Mobile broadband (MBB) power management for connected standby platforms

An MBB device supports one or more cellular radio technologies, such as GSM, 3G, CDMA, or LTE. MBB devices in connected standby platforms are all required to provide the same set of power management capabilities and to implement the same general hardware configuration, regardless of the specific cellular technologies supported.

Near-field proximity (NFP) power management for connected standby platforms

An NFP device is exposed to the Windows operating system through the GUID_DEVINTERFACE_NFP Plug and Play (PnP) interface. A third-party driver, provided by the NFP device vendor, is responsible for implementing the GUI_DEVINTERFACE_NFP interface and power-managing the physical NFP device.

Sensors power management for connected standby platforms

When a sensor device is not being used by the operating system or by an application, power-management software can switch the device to a low-power mode to reduce power consumption. In a PC that supports the connected standby power model, sensor devices are expected to switch to a low-power mode shortly after the PC enters connected standby and remain in this mode until the PC exits connected standby.

Touch and pen power management for connected standby platforms

A touch controller translates capacitive touch inputs on a display to software commands to deliver to the operating system and applications. A pen digitizer translates pen input from a stylus to software commands to deliver to the operating system and applications. In a PC that supports the connected standby power model, these devices have similar power management requirements.

 

 

 

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