Bidirectional FET Charge Discharge Control Circuit
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Solution Overview
Problem
Conventional charge/discharge control circuits for secondary batteries require a large number of elements and a significant layout area, complicating the design and increasing costs.
Innovation Solution
A charge/discharge control circuit utilizing a single bidirectionally conductive field effect transistor with a control circuit monitoring the battery voltage and a switch circuit controlling the transistor's gate, reducing the number of elements and layout area by integrating essential functions into a compact configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional charge/discharge control circuits use multiple switches and transistors to control battery charge and discharge, then the reliability of charge/discharge control is improved, but the number of elements and layout area increase significantly
Solution Approach 1:
The patent applies a single bidirectionally conductive field effect transistor to perform both charge control and discharge control functions that conventionally required separate switches. This multi-functional approach reduces the number of elements while maintaining control reliability through the transistor's ability to conduct in both directions and be controlled by a single gate terminal
Solution Approach 2:
The patent merges the charge control switch and discharge control switch into a single bidirectionally conductive field effect transistor. By combining these functions into one element, the circuit achieves the same control capability with fewer components, directly addressing the contradiction between reliability and device complexity
2Manufacturing precision
If conventional charge/discharge control circuits use multiple switches and transistors, then the control precision for preventing overcharge and overdischarge is improved, but the layout area increases significantly
Solution Approach 1:
The single bidirectionally conductive field effect transistor serves multiple control functions (charge control and discharge control) that previously required separate elements. This multi-functionality maintains the precision needed for preventing overcharge and overdischarge while significantly reducing the layout area by eliminating redundant components
Solution Approach 2:
By merging the charge control and discharge control functions into a single transistor, the patent reduces the layout area while preserving control precision. The gate terminal's ability to control both directions of current flow ensures that manufacturing precision requirements are met with fewer elements
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
The solution effectively reduces the number of elements and layout area, simplifying the circuit configuration while maintaining the ability to interrupt charge and discharge currents to prevent overcharge and overdischarge, thereby enhancing the efficiency and cost-effectiveness of the battery management system.
Implementation Method 1
an n-channel field effect transistor having a drain, a source, a gate, a back gate, and a channel formed between the drain and the source; controlling charge and discharge of the secondary battery by the field effect transistor
Data Source
AI summary
Provided is a battery device including, in a charge/discharge protection circuit for controlling charge/discharge of a secondary battery by a single bidirectionally conductive field effect transistor, a charge/discharge control circuit with which the number of elements to be used is reduced to reduce the layout area. The charge/discharge control circuit includes a switch circuit for controlling a gate of the bidirectionally conductive field effect transistor based on an output of a control circuit for controlling the charge/discharge of the secondary battery, the switch circuit including a first terminal connected to a back gate of the bidirectionally conductive field effect transistor.