Power Off State Implementation in Computing Devices

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Solution Overview

Problem

Current computing devices face challenges in balancing power conservation and responsiveness, particularly in low-power states like S4 and S5, where S4 consumes more power than necessary and regulatory restrictions on power consumption in S5 states are not fully met, while maintaining low latency for wake-up.

Innovation Solution

Implementing a power off state by writing the current state to non-volatile storage before transitioning to a S5 state, allowing the controller to distinguish between shutdown and hibernation commands, thereby reducing power consumption to 0.5W and ensuring quick restarts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the computing device enters S4 sleep mode to conserve power, then power consumption is reduced, but power consumption remains higher than required by regulations and battery life is not maximized

Engineering Contradiction:

Improvepower consumptionVSAvoidcompliance with power consumption regulations

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system performs preliminary actions by saving the current state to non-volatile storage before transitioning to the S5 power-off state. This preparation ensures that when the device restarts, it can quickly restore its previous state without requiring a full boot sequence, thereby achieving both low power consumption during idle periods and fast responsiveness when needed.

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If the computing device enters S5 power off mode to maximize power savings, then power consumption is minimized, but the device cannot meet wake-up responsiveness requirements

Engineering Contradiction:

Improvepower consumptionVSAvoidwake-up responsiveness

Core Design Contradiction:

Use of energy by moving objectVSSpeed

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

3Use of energy by moving object

If the controller distinguishes between shutdown and hibernation commands to optimize power state, then power consumption is reduced and battery life is extended, but device complexity increases

Engineering Contradiction:

Improvepower consumptionVSAvoidcontroller logic complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The system introduces an intermediary mechanism - a specific register bit (such as the PF bit in the PM1 control register) - that serves as a mediator between the shutdown/hibernation commands from the operating system and the actual power state transitions. This intermediary allows the controller to distinguish between different command types and execute appropriate power management routines, balancing enhanced functionality with controlled complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP2791758B1Implementing a power off state in a computing device

Publication Date: 2019.07.10 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

Example embodiments disclosed herein relate to implementing a power down state in a computing device. A sleep command is issued to place a computing device in a sleep state in response to receipt of a power off command at the computing device. Content of memory of the computing device is written to non-volatile storage of the computing device and the computing device is placed in a power off state.