Charging Circuit Power Cutoff After Full Charge Detection

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Solution Overview

Problem

Existing charging circuits generate standby power after charging is complete, which reduces operability as they require the user to manually reconnect the charging device to restore the power supply.

Innovation Solution

A charging circuit that uses a combination of a first FET, a charging IC, and a low power control unit, including a second FET, a time constant circuit, and a CPU to manage power supply and consumption, ensuring the power supply to the charging control unit is interrupted after full charge detection, thereby reducing standby power without compromising charging operability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the power supply circuit is stopped after full charge detection, then standby power is reduced, but the operability for charging deteriorates because the plug must be pulled out and inserted again to restore power supply

Engineering Contradiction:
Improvestandby powerVSAvoidoperability for charging
Core Design Contradiction:
Loss of energyVSEase of operation

Solution Approach 1:

The charging circuit automatically restores power supply to the charging control unit when charging is detected again, without requiring user intervention. The system self-activates by detecting the charging state through the charging detection unit, which monitors charging current or voltage, and automatically re-enables the power supply circuit through the switching element, eliminating the need for manual plug reconnection.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The charging detection unit continuously monitors the charging state and provides feedback to the switching element. When charging current or voltage exceeds predetermined thresholds, the detection unit signals the switching element to restore power supply to the charging control unit, creating a closed-loop feedback system that automatically responds to charging conditions.

Inventive Principle:
Principle #23Feedback

2Ease of operation

If the power supply to charging control unit is continuously maintained, then charging operability is preserved, but standby power consumption increases

Engineering Contradiction:
Improvecharging operabilityVSAvoidstandby power consumption
Core Design Contradiction:
Ease of operationVSUse of energy by stationary object

Solution Approach 1:

The power supply state of the charging control unit is dynamically changed based on charging conditions. The switching element transitions the power supply from OFF to ON state automatically when charging is detected, and returns to OFF state when charging stops. This dynamic adaptation allows the system to maintain low standby power consumption while ensuring charging operability when needed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The switching element acts as an intermediary between the power supply circuit and the charging control unit. It controls the power flow based on signals from the charging detection unit, enabling the system to decouple continuous power supply from continuous operational readiness, thereby reducing standby power while maintaining charging capability.

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 reduces power consumption by the charging control unit after charging is complete, maintaining the second FET in an ON state during charging and using a time constant circuit to maintain it in an OFF state post-charging, thus minimizing standby power and enhancing charging operability.

Implementation Method 1

a first FET, a charging IC, and a low power control unit, including a second FET

Methodology Applied
Scientific EffectField-effect transistor operation:

Implementation Method 2

a time constant circuit to maintain it in an OFF state post-charging

Methodology Applied
Scientific EffectTime constant circuit:

Data Source

PatentEP3832842B1Charging circuit and electrical device
Publication Date: 2024.05.15 TOSHIBA TEC KK
  • EP3832842B1 patent drawingFigure 1
  • EP3832842B1 patent drawingFigure 2
  • EP3832842B1 patent drawingFigure 3

AI summary

According to one embodiment, the charging circuit includes the control unit maintains an ON state of the main switching element by being driven within the predetermined time after power is input to the input unit and stopping the function of the time constant circuit, and when the full charge detection unit detects the fully charged state, the control unit turns off the main switching element by restoring the function of the time constant circuit after the predetermined time is elapsed.