SMPS Control Circuit for Light Load Efficiency
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Solution Overview
Problem
Switch mode power supplies face inefficiencies at light loads due to high quiescent current consumption, which affects the standby time of electronic devices in always-on and always-connected modes.
Innovation Solution
A control circuit for switch mode power supplies that includes a first and second switch, where the control circuit turns ON and OFF the switches based on voltage feedback and current signals, allowing the power supply to operate in power saving mode by reducing current flow through the second switch below a bias current, thereby minimizing quiescent current and enhancing efficiency at light loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If switch mode power supply operates in normal mode with standard switching control, then power conversion efficiency is maintained at high levels, but quiescent current consumption increases significantly
Solution Approach 1:
The power supply system dynamically switches between normal mode and power saving mode based on load conditions. The control circuit detects the operating state and adjusts the switching control signals accordingly, enabling the system to adapt its operation to minimize energy consumption while maintaining required performance levels.
Solution Approach 2:
The system changes operational parameters by transitioning between different operating modes. In power saving mode, the control circuit modifies switching frequencies, duty cycles, and current thresholds to reduce quiescent current consumption, while in normal mode it maintains standard parameters for optimal power conversion efficiency.
2Loss of energy
If the control circuit reduces current flow through the second switch to below bias current level, then efficiency at light load improves, but the ability to maintain stable output voltage may be compromised
Solution Approach 1:
The control circuit continuously monitors the output voltage through feedback mechanisms and compares it with reference values. Based on the feedback signal and detected operating state, the control circuit adjusts the switching control signals to maintain output voltage stability, even when operating in power saving mode with reduced current flow through the second switch.
Solution Approach 2:
The system automatically detects its own operating state and transitions between modes without external intervention. The control circuit monitors current flow, voltage levels, and load conditions to determine when to switch to power saving mode and when to return to normal mode, ensuring continuous stable operation.
Data Source
AI summary
A switch mode power supply having an output terminal configured to provide an output voltage, the switch mode power supply has a first switch, a second switch and a control circuit. The control circuit is configured to provide a first switching control signal to turn ON and turn OFF the first switch, and when the switch mode power supply works in a power saving mode, the first switch is turned ON if a voltage feedback signal is less than a reference voltage and a current flowing through the second switch is less than a bias current.