LED Power Supply Short Circuit Protection via Time Delay
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Solution Overview
Problem
Existing LED power supply circuits face issues with short circuit protection, where current-sensitive components like MOS tubes are prone to breakdown due to high impact currents during short circuits, leading to frequent on and off cycles that can cause damage.
Innovation Solution
A power supply circuit for LED lighting that incorporates a time delay unit with a delay comparator, voltage divider resistor group, and RC charging and discharging circuit to extend the time period for turning off the load switch, preventing high-frequency cycling and potential damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply outputs very low system input power or low frequency power when short circuit occurs, then the power supply can automatically return to normal work after withdrawal of short circuit, but the current-sensitive components will be breakdown due to large impact current reaching tens to hundreds of amps
Solution Approach 1:
The patent applies preliminary action by introducing a time delay unit that delays the shutdown of the load switch for a predetermined time period after short circuit detection. This delay allows the impact current to subside before the switch is turned off, preventing the switch from operating under excessive current conditions and thereby avoiding component breakdown while still providing effective short circuit protection.
2Reliability
If the load switch is turned on or turned off frequently to protect against short circuits, then short circuit protection is achieved, but the load switch will be burnt due to high-frequency cycling
Solution Approach 1:
The time delay unit performs preliminary action by introducing a delay period before the load switch is turned off after short circuit detection. This preliminary delay prevents immediate high-frequency cycling of the switch, allowing it to settle and reducing thermal stress accumulation that would otherwise cause the switch to burn out from frequent on-off cycles.
Solution Approach 2:
The patent applies beforehand cushioning by using the time delay unit to cushion the impact of frequent switching. The delay period acts as a protective buffer that prevents the load switch from being subjected to continuous high-frequency cycling, thereby cushioning against thermal and mechanical stress that would lead to switch burnout and extending its operational life.
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
Effectively protects the load switch from burning and prevents the power supply circuit from failing by ensuring a controlled and delayed shutdown during short circuits, thereby extending the lifespan of the components.
Implementation Method 1
a RC charging and discharging circuit, wherein the output terminal of the comparing detecting unit is electrically connected to an inverting input end of the delay comparator, a non-inverting input end of delay comparator is electrically connected to the output terminal of the voltage divider resistor group, the RC charging and discharging circuit comprises a capacitor electrically connected between the inverting input end of the delay comparator and the output terminal of the delay comparator, and a resistor electrically connected between the output terminal of the comparing detecting unit and ground
Data Source
Figure 1
Figure 2
AI summary
A power supply circuit (100) for LED lighting comprising: an LED power prime circuit (10); a load (20) electrically connected to output terminals of the LED power prime circuit; a short circuit protection switch module (30) electrically connected between the LED power prime circuit (10) and the load, wherin the short circuit protection switch module (30) comprises a load switch (301) configured for turning on or turning off the load; a circuit detecting module (40) electrically connected to the short circuit protection switch module (30), the circuit detecting module (40) comprising a comparing detecting unit (41) and a time delay unit (42), wherein the comparing detecting unit (41) is adapted to compare the output voltage of the LED power prime circuit (10) and a predetermined reference voltage and output a controlling signal according to the comparison result and wherein the time delay unit (42) is adapted to output a switch control signal after a delay time for a predetermined time in accordance with the controlling signal of the comparing detecting unit (41); and a controlling switch module (50) configured for turning on or turning off the load switch (301) in accordance with the switch control signal outputted by the time delay unit (42) so as to turn on or turn off the power supply for the load.