Battery Protection Switch Circuit for Faster Fast-Charge Activation
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Solution Overview
Problem
Existing battery protection circuits using MOS field-effect transistors result in prolonged activation and slow transition to fast charge phases, leading to poor user experience due to excessive voltage drops in discharge transistors, which prolong charging times.
Innovation Solution
A switch circuit with a first switch module having a reduced reverse conduction voltage, utilizing a Schottky diode in parallel with a switch transistor to minimize voltage drop, allowing earlier use of fast charge currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ordinary MOS field-effect transistors are used as discharge transistors in battery protection circuits, then the circuit provides adequate protection functionality, but the voltage drop across the transistor is excessive, prolonging the activation time and delaying transition to fast charge phase
Solution Approach 1:
The patent changes the key parameter of reverse conduction voltage by replacing the ordinary MOS field-effect transistor with a depletion-type MOS field-effect transistor. This parameter change reduces the reverse conduction voltage from typically 0.7-1.2V to below 0.3V, enabling faster battery activation and earlier transition to fast charge phase while maintaining protection functionality
Solution Approach 2:
The patent introduces a parallel conduction path using a diode that copies the protection function. The diode provides an alternative current path during discharge protection, working alongside the depletion-type MOS transistor to share the protection functionality while reducing overall voltage drop and activation time
2Device complexity
If ordinary MOS field-effect transistors are used, then the circuit design is simple and familiar, but the transition to fast charge phase is slow, reducing charging efficiency and user experience
Solution Approach 1:
By changing the transistor type parameter from enhancement-mode MOS to depletion-mode MOS, the patent achieves lower on-resistance and reduced voltage drop, which directly improves charging speed and enables faster transition to fast charge phase while adding minimal complexity to the circuit design
Solution Approach 2:
The patent introduces a diode as an intermediary element that provides an additional conduction path. This intermediary component works in parallel with the depletion-type MOS transistor to reduce the overall voltage drop and enable faster charging without significantly increasing circuit complexity
3Device complexity
If standard silicon diode voltage thresholds are used for fast charge activation, then the control logic is straightforward, but the activation voltage is too high, prolonging waiting time and reducing user experience
Solution Approach 1:
The patent changes the voltage threshold parameter by using a diode with lower forward voltage drop characteristics. This parameter change allows the fast charge activation threshold to be reached earlier during charging, reducing waiting time while keeping the control logic relatively simple through adjusted voltage comparison thresholds
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
Reduces charging time from activation to fast charge phase by a quarter, improving user experience through faster battery activation and reduced waiting times.
Implementation Method 1
utilizing a Schottky diode in parallel with a switch transistor to minimize voltage drop
Data Source
AI summary
Examples of the disclosure provide a switch circuit. The switch circuit comprises a first switch module, where the first switch module has a first end used to be connected to a first end of a path to be controlled, a second end used to be connected to a second end of the path to be controlled, and a control end used to receive a first control signal. A reverse conduction voltage of the first switch module is less than a preset voltage at the time of being turned off. The preset voltage is related to a voltage of a body diode of a standard silicon diode.