Power Selector Circuit for Battery Lifetime Extension

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Solution Overview

Problem

Modern integrated circuits face challenges in achieving low-power specifications due to excessive leakage currents, and existing power selector circuits are inefficient in managing power supplies, leading to battery drain and occupying significant area.

Innovation Solution

A power selector circuit that switches between a regulated power supply and a battery supply based on a threshold voltage, using a control logic circuit and power-signal switching circuit to ensure continuous power to always-on domains while minimizing battery usage, with a diode block and bias circuit providing a constant internal power supply.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a power selector circuit uses a diode bridge to select the highest voltage supply, then the always-on domain is constantly powered, but the battery may discharge unnecessarily when the regulated supply is sufficient

Engineering Contradiction:
Improvecontinuous power supply to always-on domainVSAvoidbattery discharge
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the selection parameter from purely voltage-based (diode bridge) to power-level-based comparison. The power selector circuit compares the regulated supply voltage against a threshold voltage that represents the minimum required power level, rather than simply selecting the highest voltage source. This allows the circuit to recognize when the regulated supply is sufficient and prevent unnecessary battery discharge.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a power selector circuit as an intermediary between the power supplies and the always-on domain. This intermediary actively manages power selection based on power level comparisons, rather than passively following voltage levels as a diode bridge would. The power selector circuit acts as a smart mediator that prevents energy waste by making informed decisions about which power source to use.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Duration of action of moving object

If a power selector circuit is designed to assess and select between multiple power supplies, then battery lifetime is maximized, but the circuit occupies significant area and increases complexity

Engineering Contradiction:
Improvebattery lifetimeVSAvoidcircuit area
Core Design Contradiction:
Duration of action of moving objectVSArea of stationary object

Solution Approach 1:

The patent segments the power management functionality into distinct modular components: a voltage comparison unit that compares regulated supply voltage against threshold voltage, a power level assessment unit, and a power selection unit. This segmentation allows each component to be optimized independently and reduces overall circuit area by eliminating redundant functionality that would exist in a monolithic design.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts only the essential power selection functionality needed to maximize battery lifetime, removing unnecessary complexity. Instead of implementing a full-featured power management system, the design extracts and implements only the critical voltage comparison and power level assessment functions, significantly reducing circuit area while maintaining the primary goal of extending battery lifetime.

Inventive Principle:
Principle #2Taking out (Extraction)

3Loss of energy

If a power selector circuit uses complex control logic to optimize power selection, then energy efficiency improves, but the circuit becomes more complex and harder to implement

Engineering Contradiction:
Improvepower lossVSAvoidcircuit complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical or electronic control logic with a simplified voltage comparison mechanism. Instead of using complex control circuits to assess power levels and make selection decisions, the design uses direct voltage comparison against a threshold, which is inherently simpler to implement and requires fewer components while achieving the same energy efficiency goals.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The power selector circuit uses the regulated supply voltage itself as the basis for making selection decisions, rather than requiring external control signals or complex sensing mechanisms. The circuit self-assesses the power availability by comparing the incoming voltage against the threshold, eliminating the need for additional control logic and reducing overall system complexity.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2804285B1Power arbitration method and apparatus having a control logic circuit for assessing and selecting power supplies
Publication Date: 2019.03.27 NXP BV
  • EP2804285B1 patent drawingFigure 1
  • EP2804285B1 patent drawingFigure 2A
  • EP2804285B1 patent drawingFigure 2B

AI summary

A power selector for switching power supplies is implemented using a variety of methods and devices. According to an example embodiment of the present disclosure, an arrangement provides power to a circuit by selecting between a first supply and a second supply. The first power circuit provides a regulated level of power to the integrated circuit (IC) having an operating power level specified as a circuit operating level for providing power to the IC. The second power circuit provides power to the IC. A power-signal arbitration circuit for assessing VDDREG and whether the second power circuit is to provide power to the IC as an alternative to the first power circuit providing power to the IC is based on a threshold power level indicative of the specified operating power level and the regulated level of power. Based on the power-signal arbitration circuit's assessment, providing an arbitration-control signal to the power-signal switching circuit.