DC-DC Converter Input Current Limiting for Battery Peak Protection

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Solution Overview

Problem

Batteries with a small form factor, commonly used in mobile electronic devices, are vulnerable to damage from high current peaks drawn by DC-to-DC converters, especially when operating in discontinuous conduction mode, and conventional protection methods like capacitors or resistors are either too large or inefficient.

Innovation Solution

A current limiting system using a current generator with high-gain and high-bandwidth closed-loop control, coupled with a filter capacitor and voltage control circuitry, to regulate current and voltage across the DC-to-DC converter, effectively limiting peak currents and reducing power loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional protection methods like capacitors or resistors are used to protect batteries from high current peaks, then battery protection is improved, but device size increases or protection efficiency decreases

Engineering Contradiction:

Improvebattery protectionVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The patent replaces conventional passive protection methods (capacitors and resistors) with an active electronic control system. The current generator uses closed-loop control with feedback circuitry to actively regulate and limit current peaks, substituting the mechanical/passive approach with an electronic control approach that achieves better protection in a smaller form factor

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system dynamically changes electrical parameters through closed-loop control. The current generator adjusts its output parameters (current magnitude, voltage) in real-time based on feedback, enabling adaptive protection that responds to actual operating conditions rather than relying on fixed passive components

Inventive Principle:

Principle #35Parameter changes

2Reliability

If conventional protection methods like capacitors or resistors are used to protect batteries from high current peaks, then battery protection is improved, but power loss increases

Engineering Contradiction:

Improvebattery protectionVSAvoidpower loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The active electronic control system replaces passive resistive protection methods. Instead of using resistors that dissipate power as heat, the current generator uses controlled electronic switching and regulation to limit current peaks, significantly reducing unnecessary power loss while maintaining protection effectiveness

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The closed-loop control system continuously monitors operating conditions and adjusts the current generator output accordingly. This feedback mechanism ensures protection is applied only when needed (during current peaks) rather than continuously, minimizing power loss while maintaining reliable battery protection

Inventive Principle:

Principle #23Feedback

3Power

If DC-to-DC converters operate in discontinuous conduction mode to meet power requirements, then power delivery is improved, but current peaks increase damaging the battery

Engineering Contradiction:

Improvepower deliveryVSAvoidcurrent peaks

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The current generator acts as an intermediary component between the battery and the DC-to-DC converter. It mediates the interaction by limiting current peaks from the converter while allowing the converter to operate in discontinuous conduction mode, thus protecting the battery without sacrificing power delivery capability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The current generator applies preliminary protective action by preemptively limiting current peaks before they can reach and damage the battery. The closed-loop control system anticipates and prevents harmful current excursions while allowing the DC-to-DC converter to maintain its efficient discontinuous conduction mode operation

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentEP4625788A1Current limiting systems and associated methods

Publication Date: 2025.10.01 ANALOG DEVICES INT UNLTD CO

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AI summary

A current limiting system for a direct-current-to-direct-current (DC-to-DC) converter includes a current generator, voltage control circuitry, and a filter capacitor. The current generator is electrically coupled between an energy source node and a converter input power node, and the current generator is configured to limit a magnitude of a direct current (DC) component of current flowing through the current generator to a predetermined maximum value and to attenuate one or more alternating current (AC) components of current flowing through the current generator. The voltage control circuitry is electrically coupled to the current generator and is configured to generate a control signal for controlling operation of the DC-to-DC converter to regulate a magnitude of a voltage across the current generator. The filter capacitor is electrically coupled between the converter input power node and a reference node.