Switching Power Supply Mode Control for Stable PSK-CCM Transition
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Solution Overview
Problem
Existing switching power supplies experience oscillations in output voltage during transitions between pulse suppression mode (PSK) and continuous conduction mode (CCM) when operating with average output loads, and there is a need for more efficient and energy-saving solutions.
Innovation Solution
Implementing a comparator that compares the output voltage with a reference voltage, ensuring the comparator indicates the output voltage is greater than the reference for at least 20% of the conduction time of a switch, and transitioning between modes based on this comparison and zero current detection, using PMOS and NMOS transistors to manage the switching power supply's operating modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the switching power supply transitions between pulse suppression mode and continuous conduction mode, then the power supply can adapt to different load conditions, but oscillations occur in the output voltage during mode transitions
Solution Approach 1:
The patent applies preliminary action by forcing the comparator output to a specific state for at least 20% of the conduction time before actual mode transition occurs. This pre-conditioning of the comparator state prevents abrupt transitions that cause oscillations, allowing the system to smoothly adapt between pulse suppression mode and continuous conduction mode while maintaining output voltage stability.
2Use of energy by moving object
If the switching power supply operates in pulse suppression mode to save energy, then energy consumption is reduced, but transition to continuous conduction mode requires recharging the coil which consumes additional energy
Solution Approach 1:
The patent prepares the system for mode transition by maintaining the comparator output in a forced state during the conduction time, which pre-charges or pre-discharges the coil as needed. This preliminary action eliminates the need for additional recharging operations when transitioning from pulse suppression mode to continuous conduction mode, thereby reducing energy loss during mode transitions.
3Measurement precision
If the comparator continuously monitors output voltage to ensure accurate mode transition, then mode switching accuracy is improved, but energy consumption increases
Solution Approach 1:
The patent implements periodic action by forcing the comparator output to a specific state for at least 20% of the conduction time, rather than continuously monitoring and switching. This periodic forcing reduces the active switching operations of the comparator while still ensuring accurate mode transition detection, thereby reducing comparator energy consumption while maintaining measurement precision.
Data Source
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AI summary
The present description relates to a switching power supply (100) comprising: - a first switch (T101) connecting a first node receiving a first supply voltage (VDD) to a second node providing a second output voltage (VFB); - a comparator (FB101) adapted to compare said second output voltage (VFB) with a third comparison voltage (Vref), in which, when the switching power supply operates in a pulse suppression mode (PSK), the comparator is adapted to indicate that the second output voltage (VFB) is greater than the third comparison voltage (Vref) during a part of the conduction phase of said first switch (T101).