Switching Control Circuit for Power Supply Mode Transition
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Solution Overview
Problem
Switching power supply circuits face issues with maintaining normal operation when shifting modes, particularly at light loads, leading to potential power supply voltage drops and output voltage deviations from target levels.
Innovation Solution
A switching control circuit that includes a transformer with primary, secondary, and auxiliary coils, and a transistor to control current, operating based on a power supply voltage from the auxiliary coil, which outputs drive signals to manage switching operations across normal and burst modes, adjusting according to load power consumption and transition conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the switching power supply circuit operates in burst mode to enhance efficiency at light load, then energy efficiency is improved, but the power supply voltage may drop causing control circuit malfunction
Solution Approach 1:
The control circuit detects power supply voltage before it drops to a critical level and proactively transitions from burst mode to normal mode in advance. This preliminary detection and action prevents the voltage from dropping to a level that would cause control circuit malfunction, thereby maintaining reliability while still operating in efficient burst mode during appropriate conditions.
2Loss of energy
If the switching power supply circuit continues to operate in burst mode during transient load changes, then energy efficiency is maintained, but the output voltage greatly deviates from target level
Solution Approach 1:
The control circuit continuously monitors the output voltage and uses this feedback to determine when to transition between operating modes. When the load changes transiently causing output voltage deviation, the feedback mechanism detects this condition and triggers a mode transition from burst mode to normal mode, correcting the voltage deviation while maintaining efficiency during stable light-load conditions.
3Loss of energy
If the switching operation is intermittently stopped to enhance efficiency at light load, then energy efficiency is improved, but the power supply voltage stability deteriorates
Solution Approach 1:
The power supply circuit dynamically adjusts its operating mode based on real-time detection of power supply voltage and load conditions. The system transitions between burst mode (for efficiency) and normal mode (for stability) according to detected conditions, creating a dynamic system that optimizes both efficiency and voltage stability rather than operating in a fixed mode.
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
This solution enables the switching power supply circuit to operate in appropriate modes, maintaining stable output voltage and enhancing efficiency by adjusting switching frequencies and modes based on load conditions, preventing power supply voltage drops and output deviations.
Implementation Method 1
a transformer including a primary coil provided on a primary side, a secondary coil provided on a secondary side, and an auxiliary coil magnetically coupled to the primary coil or the secondary coil
Data Source
AI summary
A switching control circuit for controlling a power supply circuit having a transformer and a transistor. The switching control circuit is configured to operate based on a power supply voltage that corresponds to a voltage from an auxiliary coil of the transformer. The switching control circuit includes a drive signal output circuit that outputs a drive signal that corresponds to an operation mode of the power supply circuit, the operation mode including a burst mode, a drive circuit that performs switching of the transistor based on the drive signal outputted by the drive signal output circuit, and a control circuit that outputs, to the drive signal output circuit, a control signal for operating the power supply circuit in the burst mode, when a first transition condition or a second transition condition is satisfied, the first transition condition including time as a condition, and the second transition condition not including time as a condition.