Switch-Mode USB Charging Circuit for Mobile Devices
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Solution Overview
Problem
USB ports provide limited power and existing Low Drop-Out (linear mode) circuits are inefficient, failing to meet the clean supply voltage requirements of mobile devices effectively.
Innovation Solution
A USB-compliant charging and power supply circuit using switch-mode battery charging circuitry with semiconductor switches to variably restrict current to the battery when voltage is low, ensuring the electronic system receives sufficient power while the battery is charged with additional available power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Low Drop-Out (linear mode) circuits are used to provide clean supply voltage, then voltage cleanliness is improved, but power efficiency deteriorates
Solution Approach 1:
The patent transitions from linear mode operation to switch-mode operation, fundamentally changing the operating parameters of the power conversion circuit. This allows the system to achieve both clean voltage output and high efficiency by using pulsed switching with controlled duty cycles rather than continuous linear regulation
Solution Approach 2:
The patent replaces the mechanical/continuous operation of linear regulators with an electronic switching mechanism. The switch-mode converter uses semiconductor switches operating in saturation and cutoff regions, substituting the continuous analog control of linear mode with discrete switching action followed by filtering to produce clean voltage
2Ease of operation
If USB ports are used to supply charging power, then device portability and simplicity are improved, but available power deteriorates
Solution Approach 1:
The patent implements dynamic power management where the system adapts its operation based on available input power. The controller adjusts switching parameters, duty cycles, and power distribution dynamically to maximize utilization of limited USB power while maintaining functionality
Solution Approach 2:
The power supply circuit is designed to universally accept different input power sources (USB ports, AC adapters, battery) and adapt its operation accordingly. The same circuit architecture handles both low-power USB charging and higher-power AC charging scenarios
3Loss of energy
If switch-mode battery charging circuitry is used to increase power efficiency, then power conversion efficiency is improved, but circuit complexity deteriorates
Solution Approach 1:
The patent combines multiple functions into integrated circuit blocks: the switch-mode charging circuit integrates battery charging, system power supply, and voltage regulation functions. The controller integrates multiple control loops (voltage regulation, current limiting, power management) into a single control unit, reducing overall system complexity despite the advanced functionality
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 enhances power efficiency by allowing greater output current than input current, maintaining system functionality even when battery voltage is low, and ensures USB compliance by regulating voltage effectively.
Implementation Method 1
switch-mode battery charging circuitry for receiving power from an external power source and for supplying output power
Implementation Method 2
Battery isolation circuitry includes a semiconductor switch connecting the output node to the battery. The battery isolation circuitry senses voltage at the output node and variably restricts current to the battery when the voltage is below a minimum voltage value by operationally controlling the semiconductor switch
Data Source
AI summary
Charging and power supply for mobile devices is disclosed. A USB-compliant charging and power supply circuit includes switch-mode battery charging circuitry for receiving power from an external power source and for supplying output power through an output node to an electronic system of an electronic communication device and a battery. Battery isolation circuitry includes a semiconductor switch connecting the output node to the battery. The battery isolation circuitry senses voltage at the output node and variably restricts current to the battery when the voltage is below a minimum voltage value by operationally controlling the semiconductor switch as current passes through it. During variable current restriction the electronic system is supplied required power with said battery being supplied any additional available power.