Multi-phase Power Supply Controller Using Shared Error Amplifier

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Solution Overview

Problem

Existing multi-phase power supply systems face challenges in equally distributing load current between phases due to offset errors and inaccuracies in PWM circuits and switches, leading to increased costs from oversized components.

Innovation Solution

A multi-phase power supply system and controller design that utilizes the same error amplifier and comparators for all channels, generating multiple ramp signals to minimize offset errors and distribute load current more evenly, allowing for smaller power switches and passive components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If different PWM comparators and passive components are used for each phase, then each phase can operate independently, but offset errors and component variations cause unequal load current distribution requiring oversized components

Engineering Contradiction:

Improveindependent phase operationVSAvoidload current distribution accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies universality by using a single error amplifier and shared passive components (ramp capacitors, resistors) for all PWM phases instead of dedicated components for each phase. This shared architecture reduces component variations and offset errors while maintaining independent phase operation through sequential timing control, directly resolving the contradiction between independent operation and current distribution accuracy.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If each channel is sized to carry maximum current, then load sharing is ensured, but component sizes and system costs increase

Engineering Contradiction:

Improveload sharing capabilityVSAvoidcomponent size

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements feedback by using a single error amplifier that receives feedback from the output voltage and sequentially controls each PWM phase. The error amplifier continuously monitors the output and adjusts each phase's duty cycle accordingly, enabling accurate load current distribution without requiring each channel to be oversized, thus resolving the contradiction between reliability and device complexity.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If multiple dedicated components are used per phase, then phase independence is maintained, but system cost and component count increase

Engineering Contradiction:

Improvephase independenceVSAvoidsystem cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent applies merging by combining the error amplifier and passive components into a shared resource for all PWM phases. Instead of having dedicated error amplifiers and components for each phase, the system merges these elements into a single shared architecture that sequentially serves all phases, reducing component count and system cost while maintaining phase independence through timing control.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS7477084B2Multi-phase power supply controller and method therefor

Publication Date: 2009.01.13 SEMICON COMPONENTS IND LLC

AI summary

In one embodiment, a power supply controller is configured to use a plurality of ramp signals to generate a plurality of PWM control signals.