Mobile Phone Overvoltage Protection Using FET Switch
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Solution Overview
Problem
Existing mobile phone apparatuses face challenges in providing power to devices at low cost without lowering the output voltage of a rechargeable battery and ensuring overvoltage protection when the battery is not connected, with existing solutions being either costly or unstable.
Innovation Solution
A mobile phone apparatus with a charger and a main telephone unit that includes a rechargeable battery detection unit, an overvoltage protection unit, and a controller to manage power supply, using a field-effect transistor switch to maintain stable voltage and prevent overvoltage, allowing efficient power delivery to devices without lowering the battery voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a voltage booster circuit is used to increase power for backlight drive, then the light emission amount of backlight is increased, but the cost increases and efficiency decreases due to overvoltage protection requirements
Solution Approach 1:
The patent introduces a field-effect transistor (FET) as an intermediary switching element between the rechargeable battery and the backlight drive circuit. The FET acts as a controlled switch that enables or disables power flow based on battery connection status, eliminating the need for complex overvoltage protection circuits while maintaining safe operation. This intermediary device simplifies the overall system architecture and reduces cost.
Solution Approach 2:
The patent changes the control parameter from continuous voltage regulation (requiring complex protection circuits) to discrete on/off switching via FET gate control. By transitioning from analog voltage management to digital-like switching control, the system achieves the same safety function with simpler, more cost-effective components while maintaining efficiency.
2Device complexity
If supply power from charger is applied directly via Zener diode, then the voltage protection is simplified, but the voltage stability becomes poor
Solution Approach 1:
The FET serves as a smart intermediary that provides both switching control and protection functions. Unlike passive Zener diodes that only clamp voltage, the actively controlled FET can completely disconnect the circuit when needed, providing superior protection while maintaining voltage stability through precise gate control based on battery detection signals.
Solution Approach 2:
The system employs a rechargeable battery detection unit that automatically detects battery presence and generates control signals to the FET gate. This self-service mechanism eliminates the need for external complex protection circuits, as the system autonomously manages its own power distribution and protection based on real-time battery status.
3Reliability
If overvoltage protection is implemented in booster circuit, then the safety is improved, but the cost increases and efficiency decreases
Solution Approach 1:
The FET acts as a protective intermediary that isolates the load from potential overvoltage conditions by completely disconnecting the power path when the battery is not connected. This active switching approach provides robust overvoltage protection without requiring additional protection components, thereby reducing cost and maintaining efficiency.
Solution Approach 2:
The system performs preliminary detection of battery connection status before enabling power flow to the backlight circuit. By detecting battery presence in advance and pre-configuring the FET switch state accordingly, the system prevents overvoltage conditions from occurring in the first place, providing proactive protection rather than reactive correction.
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
Enables power supply to devices at low cost and high efficiency while preventing overvoltage, ensuring reliable operation and user notification of battery status, with reduced manufacturing complexity.
Implementation Method 1
using a field-effect transistor switch to maintain stable voltage and prevent overvoltage, allowing efficient power delivery to devices without lowering the battery voltage
Data Source
AI summary
A mobile phone apparatus is provided. The mobile phone apparatus includes a charger for supplying power to a rechargeable battery including a connection portion and a main telephone unit. The main telephone unit includes a rechargeable battery detection unit which detects whether the connection portion of the rechargeable battery is connected to the main telephone unit; an overvoltage protection unit which is coupled to the connection portion of the rechargeable battery and switches between an active state of supplying power output from the connection portion and an inactive state of not supplying power output from the connection portion; and a controller which controls the overvoltage protection unit to switch the overvoltage protection unit into the active state if the rechargeable battery detection unit detects that the rechargeable battery is connected.