Transformer Switching Control for Stable Burst-Mode Power Supply
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Solution Overview
Problem
Power supply circuits experience instability when a load transitions from a normal mode to a burst mode due to differences in transistor switching methods, leading to unpredictable operation.
Innovation Solution
A switching control circuit that includes a drive signal output circuit and a driver circuit to manage the switching of first and second transistors, transitioning from a normal mode to a burst mode by reducing the time period of transistor switching in response to output voltage changes, ensuring stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the power supply circuit switches transistors using different methods between normal mode and burst mode, then the circuit can adapt to different load conditions, but the operation becomes unstable during mode transitions
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the switching frequency and duty cycle of the transistors based on the output voltage level. When the output voltage rises above the first level, the control circuit modifies the switching parameters to transition from normal mode to burst mode, maintaining adaptability while ensuring stable operation through controlled parameter variation.
Solution Approach 2:
The patent implements dynamics by enabling the power supply circuit to dynamically switch between normal mode and burst mode operation based on real-time output voltage conditions. The control circuit continuously monitors the output voltage and adjusts the transistor switching method accordingly, allowing the system to adapt to changing load conditions while maintaining operational stability through smooth mode transitions.
2Reliability
If the first time period is reduced in burst mode to control output voltage, then the output voltage stability is improved, but the switching frequency increases
Solution Approach 1:
The patent applies periodic action by implementing burst mode operation where the transistors are switched continuously during the first time period and then stopped during the second time period, repeating this pattern in a predetermined cycle. This periodic switching pattern allows the circuit to maintain output voltage stability by controlling the average power delivery while managing the switching frequency through the burst cycle duration.
Data Source
AI summary
A switching control circuit for a power supply circuit that includes a transformer including primary and secondary coils, and first and second transistors controlling a current flowing through the primary coil. The power supply circuit generates an output voltage at a target level. The switching control circuit controls switching of the first and second transistors. The switching control circuit includes: a drive signal output circuit configured to output drive signals according to a normal mode, when the output voltage is lower than a first level, and output the drive signals according to a burst mode, when the output voltage is higher than the first level; and a driver circuit configured to switch the first and second transistors in response to the drive signals. The drive signal output circuit reduces a first time period in the burst mode, in response to the output voltage rising above the first level.