Low Power Mode Management Circuit with Delayable Wake-Up Request

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Solution Overview

Problem

In battery-powered embedded systems like mobile phones, efficient wake-up from a low-power sleep state is crucial for reducing power consumption, but existing methods often require the system controller to be awake, contributing to increased power usage due to frequent system-level wake-ups and immediate processing of wake-up events.

Innovation Solution

A circuit arrangement with a clock generator and a controller that introduces a delay in returning from low power mode by triggering the circuit when a threshold value of clock cycles is reached, allowing for synchronization of multiple wake-up events and reducing the number of system wake-ups by distinguishing between delayable and undelayable requests.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the system immediately returns from low power mode upon receiving a wake-up request, then the response time is improved, but the power consumption increases due to frequent system wake-ups

Engineering Contradiction:

Improvewake-up response timeVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The patent applies preliminary action by having the controller wait for a threshold number of clock cycles after receiving a wake-up request before actually triggering the circuit to return from low power mode. This delay allows multiple wake-up requests to accumulate and be processed together, reducing the frequency of system wake-ups and thereby lowering power consumption while maintaining acceptable response time.

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If the system consolidates multiple wake-up requests into a single wake-up event, then the power consumption is reduced, but the wake-up response time increases

Engineering Contradiction:

Improvepower consumptionVSAvoidwake-up delay

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the wake-up delay configurable through a threshold value that can be adjusted based on system requirements. The controller dynamically decides when to trigger the wake-up based on whether the clock cycle count reaches the threshold, allowing optimization between power savings and response time requirements.

Inventive Principle:

Principle #15Dynamics

3Productivity

If the CPU is immediately involved in processing wake-up events, then the processing speed is improved, but the power consumption increases

Engineering Contradiction:

Improvewake-up processing speedVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent applies preliminary action by having the controller prepare and batch multiple wake-up requests before triggering CPU involvement. The CPU is not immediately involved in each individual wake-up event but rather in consolidated processing after the delay threshold is reached, reducing the frequency of CPU activation and thereby lowering power consumption.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9021287B2Circuit arrangement and method for low power mode management with delayable request

Publication Date: 2015.04.28 APPLE INC

AI summary

For example, a circuit arrangement is provided comprising a clock generator configured to generate a clock signal, a circuit having a low power mode, and a controller, configured to receive, when the circuit is in the low power mode, a request specifying that the circuit should return from the low power mode and trigger the circuit to return from the low power mode when the number of clock cycles of the clock signal since the reception of the request has reached a threshold value.