Multi-module Current Sharing via Inverted Buffered Amplifier

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Solution Overview

Problem

Existing current sharing schemes for independent power modules are limited by restricted pin availability, limited dynamic range, and inability to disable current sharing without additional pins, which affects output voltage accuracy and flexibility, especially in multi-phase operations.

Innovation Solution

A circuit configuration that includes an error amplifier, a buffered differential amplifier, and a correction current source, where a resistor (RSHARE) enables or disables current sharing and controls the correction current, allowing programmable dynamic range and internal COMP voltage adjustment without adding extra pins, using a resistor divider network for voltage correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a correction current source is applied to the positive input of the error amplifier, then current sharing is achieved, but the choices for feedback resistor and compensation network resistors are limited

Engineering Contradiction:

Improvecurrent sharingVSAvoidresistor selection flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent applies the correction current to the negative input of the buffered differential amplifier instead of the positive input of the error amplifier. This inversion of the conventional approach allows the feedback resistor and compensation network resistors to be independently selected, resolving the limitation on resistor choice while maintaining current sharing functionality

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent separates the current sharing function from the voltage feedback function by using distinct circuit paths. The correction current is applied to the buffered differential amplifier's negative input, while the feedback network connects to the error amplifier's negative input. This segmentation allows independent optimization of both functions without mutual interference

Inventive Principle:

Principle #1Segmentation

2Reliability

If the correction current is sourced to the positive input of the buffered differential amplifier, then current sharing is achieved, but the resistor divider network choices are limited and not suitable for wide output voltage applications

Engineering Contradiction:

Improvecurrent sharingVSAvoidoutput voltage range

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Instead of sourcing correction current to the positive input of the buffered differential amplifier, the patent applies it to the negative input. This inversion allows the positive input to be freely connected to the feedback network, enabling wide output voltage applications with flexible resistor divider configurations

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent creates a universal current sharing scheme that works across wide output voltage ranges by making the feedback network and compensation network independently configurable. The circuit can accommodate different voltage applications by simply changing the resistor values without affecting current sharing performance

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If the correction current is applied to the positive input of the error amplifier, then current sharing is achieved, but the current sharing range is limited and VREF node is not accessible

Engineering Contradiction:

Improvecurrent sharingVSAvoidcurrent sharing range

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent inverts the conventional connection by applying correction current to the negative input of the buffered differential amplifier rather than the positive input of the error amplifier. This provides access to the VREF node and enables a wider programmable current sharing range through the RSHARE resistor

Inventive Principle:

Principle #13The other way round (Inversion)

4Reliability

If existing current sharing configurations are used, then current balance is achieved, but additional pins are required and output voltage accuracy is affected

Engineering Contradiction:

Improvecurrent balanceVSAvoidpin count

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the current sharing function with the existing feedback and compensation networks by applying the correction current at the negative input of the buffered differential amplifier, which is already part of the voltage control loop. This eliminates the need for additional pins while maintaining current balance

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent creates a multi-functional circuit where the same buffered differential amplifier and feedback network serve both voltage regulation and current sharing purposes. The RSHARE resistor enables current sharing control without requiring dedicated pins, making the circuit universally applicable

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS7732941B2Multi-module current sharing scheme

Publication Date: 2010.06.08 INTERSIL AMERICAS INC

AI summary

A circuit provides multi-module current sharing for circuit modules. The circuit includes an error amplifier having a negative and a positive input and an output. The positive input of the error amplifier is connected to a reference voltage. A buffered differential amplifier has an output connected to the negative input of the error amplifier and a positive and a negative input. A correction current is sourced to the negative input of the buffered differential amplifier. A resistor connected to the negative input of the buffered differential amplifier has a value that controls the amount of current correction applied to the negative input of the buffer differential amplifier by the current correction source.