Switching Control Circuit for Burst-Mode Overvoltage Restraint
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Solution Overview
Problem
Current DC-DC converters face the challenge of preventing output voltage overvoltage when shifting from a normal mode to a burst mode during light load states.
Innovation Solution
A switching control circuit is designed to detect load states using a load detection circuit and output drive signals to manage the operation of transistors, transitioning directly from a first state to a third state without going through a second state immediately after entering burst mode, thereby preventing overvoltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the DC-DC converter performs soft end operation when shifting to burst mode, then transformer noise is reduced, but output voltage may reach overvoltage
Solution Approach 1:
The patent implements dynamic control of the drive signal output circuit by introducing multiple operational states (first state with predetermined output conditions, second state with gradually reduced ON period, third state with stopped output) and dynamically transitioning between them based on load detection. This dynamic approach allows the system to perform soft end operation (transitioning to second state) only when appropriate, thereby reducing transformer noise while preventing output voltage overvoltage by avoiding soft end when load conditions are unsuitable.
2Object-generated harmful factors
If the drive signal is outputted to gradually reduce ON period of transistors (soft end), then transformer noise is suppressed, but output voltage control precision deteriorates
Solution Approach 1:
The patent changes the operational parameters of the drive signal output circuit by defining distinct operational states with different output characteristics. The first state provides precise voltage control under normal conditions, while the second state implements soft end with gradually reduced ON period for noise suppression. The load detection circuit monitors load conditions and triggers state transitions, thereby adapting the parameter set (from precise control to noise-reduced operation) based on real-time requirements.
3Loss of energy
If the power supply circuit operates in burst mode for light load state, then energy efficiency is improved, but output voltage may become unstable
Solution Approach 1:
The patent implements a feedback mechanism through the load detection circuit that continuously monitors load conditions and provides information to the drive signal output circuit. This feedback loop enables the system to detect when the load enters light-load state and triggers the transition to burst mode operation, while also monitoring output voltage stability and preventing overvoltage conditions by controlling the transition timing and operational states.
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 restrains the output voltage from reaching overvoltage levels during mode transitions, ensuring stable voltage delivery while reducing noise in the transformer.
Implementation Method 1
a first capacitor that forms a resonant circuit with the primary coil
Data Source
AI summary
A switching control circuit for controlling switching of first and second transistors of a power supply circuit. The switching control circuit including: a load detection circuit detecting a state of a load; a drive signal output circuit outputting a drive signal that causes the power supply circuit to operate in a burst mode and a normal mode respectively when the load is light and heavy loads. The drive signal output circuit operates in a first state in which the drive signal is outputted based on a predetermined condition, a second state in which the drive signal is outputted to gradually reduce an ON period of the first and second transistors and a third state in which outputting of the drive signal is stopped, and enters the third state from the first state without going through the second state immediately after the power supply circuit starts operating in the burst mode.