USB-OTG Power Source DC-to-DC Converter Voltage Stability

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Solution Overview

Problem

Existing power supplies in handheld devices, such as those using switched capacitor charge pump circuits, face instability as battery voltage drops, leading to inadequate power delivery to external devices in USB On-the-Go mode.

Innovation Solution

A DC-DC converter and pulse generator combination is used to maintain a stable 5V supply voltage, drawing additional current as the battery discharges, with the pulse generator producing an oscillating signal to support up to 8mA current, ensuring consistent power until the battery voltage reaches a low threshold.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a switched capacitor charge pump circuit is used to generate supply voltage, then the circuit can operate with simple structure, but the voltage drops as the battery discharges

Engineering Contradiction:

Improvecircuit structureVSAvoidsupply voltage stability

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The patent employs a DC-to-DC converter that dynamically adjusts operating parameters (switching frequency, duty cycle) to maintain constant 5V output despite varying battery voltage. The converter compensates for battery discharge by increasing current draw as battery voltage drops, ensuring stable power delivery to USB-OTG peripheral devices.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If additional current is drawn as battery discharges to maintain voltage, then power stability is improved, but power consumption increases

Engineering Contradiction:

Improvesupply voltage stabilityVSAvoidpower consumption

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The DC-to-DC converter incorporates feedback control that monitors battery voltage and adjusts switching parameters accordingly. As battery voltage drops, the feedback mechanism increases the converter's current draw to maintain constant 5V output, optimizing the balance between power stability and consumption.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This solution provides a stable power supply to external devices, maintaining voltage consistency until battery depletion, thereby enhancing the operational longevity of handheld devices in USB On-the-Go mode.

Implementation Method 1

A DC-to-DC converter and pulse generator combination is used to maintain a stable 5V supply voltage, drawing additional current as the battery discharges

Methodology Applied

Scientific EffectElectrical energy conversion:

Implementation Method 2

utilizing a USB-OTG power source with a power supply module that includes rectifiers and filtration to stabilize the output

Methodology Applied

Scientific EffectRectification:

Data Source

PatentUS8035368B2Integrated circuit, universal serial bus on-the-go power source and methods for use therewith

Publication Date: 2011.10.11 NXP USA INC

AI summary

A universal serial bus on-the-go (USB-OTG) power source includes a direct-current to direct-current (DC-to-DC) converter for generating a source voltage when coupled to a battery. A pulse generator generates an oscillating signal when a USB-OTG enable signal is asserted. A power supply module generates a supply voltage from the oscillating signal and the source voltage.