Slave Device Power-Down Mode for Host Battery Life

Solution Overview

Problem

Existing slave devices with back-end modules, such as flash memory, continue to consume power even when not in use, leading to rapid battery depletion in host devices with small power supplies, and current power-down modes are inefficient, requiring significant time and power for transitions.

Innovation Solution

Implementing a power-down mode where the clock signal is stopped and a specific signal pattern is used to transition the slave device to a low-power state, reducing the time required for power-down and power-up operations, with preprocessing and postprocessing times minimized to 250 milliseconds and 100 milliseconds respectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If power is constantly supplied to the back-end module when the host device is powered on, then the back-end module can perform data access operations, but power is wasted and the battery depletes quickly

Engineering Contradiction:

Improvedata access capabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The slave device performs preprocessing operations (saving data from RAM to back-end module, updating file allocation tables) before transitioning to power-down mode, ensuring that essential data is preserved and the device can quickly resume operations without data loss when powered back up

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements periodic power cycles by transitioning between normal mode and power-down mode based on activity requirements, allowing the back-end module to be powered on only when data access is needed and powered off during idle periods, thus reducing overall power consumption while maintaining operational capability

Inventive Principle:

Principle #19Periodic action

2Use of energy by moving object

If a power-down mode is implemented to reduce power consumption, then battery life is extended, but the transition time from normal mode to power-down mode and back increases

Engineering Contradiction:

Improvepower consumptionVSAvoidpower-down transition time

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The slave device performs preprocessing operations (saving data from RAM to back-end module, updating file allocation tables) before transitioning to power-down mode, ensuring that essential data is preserved and the device can quickly resume operations without data loss when powered back up

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent minimizes the duration of power-down transition mode and power-up transition mode by optimizing the sequence and duration of operations, allowing the device to quickly transition between states without prolonged intermediate periods that would waste time

Inventive Principle:

Principle #21Skipping (Rushing through)

3Use of energy by moving object

If the back-end module is powered down to save energy, then power consumption is reduced, but data in the volatile RAM is lost and must be recovered

Engineering Contradiction:

Improvepower consumptionVSAvoiddata loss in RAM

Core Design Contradiction:

Use of energy by moving objectVSLoss of information

Solution Approach 1:

The slave device performs preprocessing operations (saving data from RAM to back-end module, updating file allocation tables) before transitioning to power-down mode, ensuring that essential data is preserved and the device can quickly resume operations without data loss when powered back up

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The back-end module acts as an intermediary storage device that receives and holds data from the volatile RAM before power-down, and provides data back to RAM after power-up, thus mediating the data loss problem caused by volatile memory clearing during power cycles

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12117887B2Slave device and host device

Publication Date: 2024.10.15 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

When a host-slave system including a host device and a slave device transitions to a power-down mode, the host device drives a CMD line in order of a high level, a low level, and a high level, and stops supplying a clock signal after a predetermined time elapses. During a power-down mode period, the slave device stops supplying a power to a back-end module. When the host device resumes the supply of the clock signal, the host-slave system returns from the power-down mode.