Power Supply Mode Switching for Peak Input Power Limiting

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Solution Overview

Problem

Devices like 802.11 compliant radios face challenges in adhering to power consumption limits, particularly during peak transmit modes, as their power consumption exceeds the specified limits, leading to potential product degradation when reducing power or using Power over Ethernet with limited input power.

Innovation Solution

A power supply with a mode selection input that switches between a tightly regulated and an open-loop mode, allowing input power averaging by increasing the duty cycle until feedback is ineffective, enabling the output voltage to vary and reducing peak input power during high-demand periods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If transmit power is reduced to meet peak power limits, then peak input power is limited, but device performance degrades

Engineering Contradiction:

Improvepeak input powerVSAvoiddevice performance

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The power supply operates in periodic cycles, alternating between a first mode during peak power demand periods and a second mode during normal periods. This periodic switching allows the system to meet peak power limits while maintaining device performance through proper timing and duty cycle control.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system changes operational parameters by switching between two distinct modes: a first mode with specific voltage regulation characteristics for peak power limitation, and a second mode with different characteristics for normal operation. This parameter change allows the system to adapt to different power demand conditions.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If CPU power is reduced through clock reduction or feature reduction, then overall power consumption is reduced, but device functionality degrades

Engineering Contradiction:

Improveoverall power consumptionVSAvoiddevice functionality

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The power management is segmented into two distinct operational modes rather than continuously reducing power across all functions. This allows the system to maintain full functionality during the second mode while limiting peak power during the first mode through controlled voltage variation.

Inventive Principle:

Principle #1Segmentation

3Power

If Power over Ethernet is used with limited maximum input power, then power consumption is controlled, but the system cannot operate during high-demand periods

Engineering Contradiction:

Improvemaximum input powerVSAvoidsystem operability

Core Design Contradiction:

PowerVSProductivity

Solution Approach 1:

The power supply dynamically adapts its characteristics by switching between two modes. During peak power demand periods, it operates in the first mode to limit input power while still providing sufficient power for operation. During normal periods, it switches to the second mode for optimal performance, thus maintaining system operability under PoE constraints.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS7659701B1Limiting peak input power

Publication Date: 2010.02.09 CISCO TECHNOLOGY INC

AI summary

In an example embodiment, a primary power supply having an input, an output and a mode selection input. The mode selection input is operative to switch the power supply between a first mode of operation and a second mode of operation. While in the first mode of operation voltage is regulated within a predefined criterion. While in the second mode of operation, voltage at the output is allowed to vary beyond the predefined criteria.