Current Control Circuitry for USB-Powered Portable Devices
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Solution Overview
Problem
Current control circuitry for rechargeable batteries in portable devices, such as those powered by USB, faces inefficiencies due to voltage drops and the need to limit current within USB specifications, which can restrict battery charging and load operation, especially when the battery is low or dead.
Innovation Solution
The implementation of current control circuitry that measures and adjusts the current to both the load and battery, ensuring the total current remains within a programmed limit, allowing for efficient charging and operation by prioritizing available power sources and bypassing the battery when it is low, thereby maintaining efficient power delivery to the load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the battery is tied directly to the load in parallel with USB power, then the load can operate when USB power is available, but the battery voltage dictates the voltage applied to the load and causes substantial voltage drop when battery voltage is low
Solution Approach 1:
The patent introduces a battery switch and control circuitry as intermediaries between the battery and the load. The battery switch can disconnect the battery from the load when USB power is available, preventing the low battery voltage from being applied to the load. The control circuitry monitors battery voltage and USB power status to intelligently control the switch, ensuring the load receives adequate voltage from USB power while the battery is protected from deep discharge.
Solution Approach 2:
The patent implements dynamic switching between power sources based on real-time conditions. The battery switch dynamically connects or disconnects the battery from the load depending on battery voltage level and USB power availability. This dynamic configuration allows the system to adapt to changing conditions, ensuring optimal performance and preventing energy loss from voltage mismatch.
2Ease of operation
If the battery is fully discharged, then the load cannot receive sufficient voltage to operate, but connecting the load directly to the battery requires several minutes of charging before any load operation
Solution Approach 1:
The battery switch acts as an intermediary that allows the load to be connected to USB power independently of the battery charge state. When USB power is available and battery voltage is low, the switch disconnects the battery from the load, allowing the load to operate directly from USB power without waiting for the battery to charge. This eliminates the charging wait time while ensuring the load receives adequate voltage.
Solution Approach 2:
The patent segments the power delivery path by introducing separate control paths for battery and USB power. The battery switch creates distinct connection paths that can be independently controlled, allowing the load to receive power from USB without requiring the battery to be charged. This segmentation enables independent operation of battery charging and load power supply.
3Reliability
If current is limited to 500 mA according to USB specification, then the current constraint is maintained, but the battery charging current and load current must share this limited current
Solution Approach 1:
The patent implements feedback control through current sensing and control circuitry that monitors the actual current draw from the USB power source. The control circuitry adjusts the battery switch state and power distribution based on feedback signals about current consumption, ensuring the total current remains within the 500 mA USB specification while optimizing battery charging speed. The system dynamically adjusts power allocation between load and battery based on real-time conditions.
Solution Approach 2:
The patent employs dynamic current sharing control where the battery switch and control circuitry continuously adjust the current distribution between the load and battery charging based on priority settings and available current. When USB power is available, the system can dynamically allocate more current to battery charging when the load requires less power, maximizing charging speed within the USB current limit.
Data Source
AI summary
Current control circuitry for controlling current supplied from a source, that may be a current-constrained source, to a load and a battery. A current limit control circuit limits current supplied by the source to the load in accord with a programmed current limit. Load current is measured, and an input charger control circuit controls magnitude of current to the battery based on the difference between measured load current and battery current programmed to be supplied to the battery, such that the sum of load current and battery current is maintained within the programmed current limit.