Single Input Terminal Circuit for USB Charger Current Configuration
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Solution Overview
Problem
Conventional USB battery charger integrated circuits require multiple terminals for configuration, which increases manufacturing costs and complexity, and do not efficiently utilize higher current charging capabilities when available.
Innovation Solution
A single terminal is used to configure the integrated circuit into three states (Q0, Q1, or Q2) by determining its connection status, allowing the circuit to set operational characteristics such as charging current based on an external resistor, reducing the number of terminals needed and enabling higher current charging when possible.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple terminals are used for configuration in conventional USB battery charger integrated circuits, then configuration flexibility is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies multi-functionality by making a single terminal (T1) perform multiple configuration functions that previously required separate terminals. The terminal can detect different voltage levels to determine charging current capacity (100mA, 500mA, or higher) and can also indicate charging status, replacing what conventional designs required as multiple dedicated terminals. This reduces terminal count while maintaining configuration flexibility.
Solution Approach 2:
The patent merges multiple configuration functions into a single terminal T1. Instead of having separate terminals for current capacity selection and status indication, the invention combines these functions so that one terminal serves both purposes through voltage level detection and open-drain output capabilities, thereby reducing overall device complexity.
2Reliability
If conventional USB ports are used with fixed current limits, then safety is improved, but charging speed and productivity are reduced
Solution Approach 1:
The patent implements dynamic current adjustment by enabling the battery charger to adapt its charging current based on the detected voltage level at terminal T1. The system can dynamically switch between 100mA, 500mA, or higher current modes depending on USB host capability and battery conditions, allowing safe operation at lower currents when needed and high-speed charging when the host supports it, thus resolving the contradiction between safety and charging speed.
Data Source
AI summary
A single terminal is usable to configure an integrated circuit into one of three states. A circuit within the integrated circuit is coupled to the terminal and determines whether the terminal: 1) is tied low by an external connection, or 2) is tied high by an external connection, or 3) is floating or is substantially floating. If the circuit determines that the terminal is floating or is substantially floating, then the circuit sets an operational characteristic of a portion of the circuit (for example, sets a maximum current with which the circuit charges a battery) to have a value that is a function of a resistance of an external resistor coupled to the terminal. If no external resistor is present, then the terminal is floating and the operational characteristic is set to have a zero value. The terminal and circuit are particularly suited to use in a USB battery charger.