Battery Protection Circuit Using Voltage Divider

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Lithium-ion battery systems are susceptible to damage from overcharging and over-discharging, and traditional protection circuits require high-voltage resistant elements, leading to increased manufacturing costs and chip area.

Innovation Solution

A charge/discharge protection circuit utilizing a P-channel MOS field-effect transistor (PMOS transistor) to maintain low-voltage resistant elements from excessive voltages, preventing damage from abnormal charger voltages without the need for high-voltage resistant components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high-voltage resistant circuit elements are used in the protection circuit, then the circuit can withstand excessive voltage from improper chargers, but the chip area and manufacturing cost increase significantly

Engineering Contradiction:

Improveprotection circuit durabilityVSAvoidchip area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent introduces a voltage divider circuit composed of first and second resistors as an intermediary between the charger input and the detection circuit. This voltage divider reduces the excessive voltage from improper chargers to a safe level that low-voltage resistant transistors can handle, while still allowing accurate detection of overcharge conditions. The intermediary voltage divider protects the detection circuit without requiring high-voltage resistant components throughout the entire circuit.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If high-voltage resistant circuit elements are used in the protection circuit, then the circuit can withstand excessive voltage from improper chargers, but the manufacturing cost increases significantly

Engineering Contradiction:

Improveprotection circuit durabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The voltage divider circuit acts as a cost-effective intermediary that protects inexpensive low-voltage resistant transistors from high-voltage damage. By using simple resistors in series to divide the voltage, the circuit achieves high-voltage tolerance without the need for expensive high-voltage resistant transistors, thereby significantly reducing manufacturing costs while maintaining protection efficacy.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs inexpensive low-voltage resistant transistors combined with a voltage divider circuit instead of expensive high-voltage resistant transistors. The voltage divider uses simple, cheap resistors that can handle the voltage division task, allowing the use of cheaper transistors throughout the detection circuit while still providing reliable protection against overvoltage conditions.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Measurement precision

If circuit elements are connected directly to charger components, then the detection circuit can monitor battery conditions, but excessive voltage from improper chargers damages the circuit elements

Engineering Contradiction:

Improvebattery condition detection accuracyVSAvoidvoltage damage to circuit elements

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The voltage divider circuit serves as a protective intermediary between the charger input and the detection transistors. It scales down the charger voltage (including excessive voltage from improper chargers) to a level safe for the low-voltage resistant transistors, enabling continuous monitoring of battery conditions without exposing the detection circuit to damaging high voltages.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 protects battery systems from overvoltage conditions using low-voltage resistant elements, reducing manufacturing costs and chip area while maintaining protection efficacy.

Implementation Method 1

A charge/discharge protection circuit utilizing a P-channel MOS field-effect transistor (PMOS transistor) to maintain low-voltage resistant elements from excessive voltages

Methodology Applied

Scientific EffectField-effect transistor operation:

Data Source

PatentUS8665572B2Battery charge/discharge protection circuit

Publication Date: 2014.03.04 BCD (SHANGHAI) MICRO ELECTRONICS LTD

AI summary

The present invention relates to a battery charge/discharge protection circuit that protects an associated battery from charge/discharge damage. The charge/discharge protection circuit includes a first terminal, a second terminal, a charge over-current detection circuit, a discharge over-current detection circuit, a short circuit detection circuit, and a PMOS transistor. A drain electrode and a gate electrode of the PMOS transistor are connected to the first terminal and the second terminal respectively. A source electrode of the PMOS transistor is connected to the charge over-current detection circuit, the discharge over-current detection circuit and the short circuit detection circuit, such that when a voltage above an overvoltage threshold is supported by the charger, the voltage of the source electrode of the PMOS transistor is maintained above a negative threshold voltage and the elements in these circuits do not receive such a voltage output by the charger.