Bypass Control Circuit for LED Overcurrent and Overtemperature Protection
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Solution Overview
Problem
Existing LED electrical connections are susceptible to malfunctions when one LED fails, leading to reduced brightness and wasted energy in the entire string, lacking overcurrent and overtemperature protection.
Innovation Solution
A control circuit with integrated overcurrent protection (OCP) and overtemperature protection (OTP) using a comparator unit, thermistor, and bypass switch to prevent current flow to the load when thresholds are exceeded, ensuring safe and reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple LEDs are connected in series and parallel to form strings, then the LED system can achieve desired brightness and power distribution, but the system becomes susceptible to malfunctions when one LED fails, causing the entire string to stop working and wasting energy
Solution Approach 1:
The patent divides the LED string into multiple independent groups, each with its own control circuit. When one LED or group fails, other groups continue to operate independently, preventing total string failure and maintaining partial functionality and power distribution.
Solution Approach 2:
The control circuit acts as an intermediary between the power source and LED groups, monitoring current and temperature to prevent failures before they occur. The bypass switch serves as an intermediary mechanism to redirect current around failed components, maintaining system reliability.
2Device complexity
If no overcurrent protection is implemented, then the circuit design is simpler, but the system lacks protection against excessive current that can damage LEDs and reduce lifespan
Solution Approach 1:
The overcurrent protection circuit proactively monitors current levels before damage occurs and preemptively activates the bypass switch when thresholds are exceeded, preventing component failure before it happens rather than reacting after damage occurs.
Solution Approach 2:
The control circuit continuously monitors current flow through the LED groups and provides feedback to the bypass switch. When current exceeds safe levels, the feedback mechanism triggers the bypass switch to activate, creating a closed-loop protection system that maintains reliability.
3Device complexity
If no overtemperature protection is implemented, then the circuit design is simpler, but the system becomes vulnerable to overheating that can cause LED failure and safety hazards
Solution Approach 1:
The temperature monitoring circuit continuously measures temperatures and activates the bypass switch before critical overheating occurs, taking preliminary protective action to prevent thermal damage to LEDs and other components.
Solution Approach 2:
The control circuit receives continuous temperature feedback from monitoring elements and adjusts the bypass switch state accordingly. When temperatures approach dangerous levels, the feedback mechanism triggers protective bypass activation, creating a closed-loop thermal management system.
4Ease of manufacture
If the entire LED string must be replaced when one LED fails, then component individuality is maintained, but energy is wasted and replacement costs increase
Solution Approach 1:
By segmenting the LED string into independently controllable groups with individual control circuits, the system allows selective operation of functional groups. When one LED or group fails, other groups continue operating, eliminating energy waste and extending system life without requiring complete string replacement.
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 control circuit effectively prevents overcurrent and overtemperature conditions, ensuring consistent LED performance and reducing energy waste by bypassing the load when protection thresholds are reached, enhancing safety and reliability.
Implementation Method 1
an overcurrent protection resistor, electrically connected between the second output port and a ground
Implementation Method 2
a thermistor, electrically connected to the comparator unit; wherein when a resistance of the thermistor overranges an over temperature protection range
Implementation Method 3
a comparator unit; wherein a node between the overcurrent protection resistor and the second output port is electrically connected to the comparator unit
Implementation Method 4
a bypass switch, electrically connected to the comparator unit, the ground, and the first pin and the second pin of the control chip; wherein when a current flowing through the overcurrent protection resistor is greater than an overcurrent protection threshold, the bypass switch bypasses the first output port to the ground
Data Source
AI summary
A control circuit includes a control chip and a protection circuit module. A first output port and a second output port of the protection circuit module are electrically connected to a load. An overcurrent protection resistor is electrically connected between the second output port and a ground. A thermistor and a node between the overcurrent protection resistor and the second output port are electrically connected to the comparator unit. A bypass switch is electrically connected to the comparator unit, the ground, and the control chip. When a current flowing through the overcurrent protection resistor is greater than an overcurrent protection threshold, or when a resistance of the thermistor overranges an over temperature protection range, the bypass switch bypasses the first output port to the ground for bypassing the load. The control circuit is reliable and miniaturized with overcurrent protection and over temperature protection in an integrated circuit.