Power Supply Controller Light Load Detection
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Solution Overview
Problem
Existing power supply systems face challenges in accurately detecting load reductions and efficiently transitioning to low consumption current modes due to limitations in monitoring high-side output transistor currents, leading to poor response times and reduced accuracy.
Innovation Solution
A power supply design incorporating a first and second switch in series, an inductor, and a controller that alternately switches the switches based on output voltage errors, with a longer switching cycle when the second switch is on, allowing for accurate light load detection and efficient power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the current of the high-side output transistor is monitored to detect light load, then the power supply can detect load changes, but the detection accuracy is poor and response is slow
Solution Approach 1:
The patent introduces an intermediary signal - the voltage at the junction between the high-side and low-side output transistors during the off-state of the low-side transistor. This voltage serves as a mediator that reflects the load current information more accurately and responds faster than direct current monitoring. The control circuit detects light load conditions by monitoring this intermediary voltage signal, achieving both high accuracy and fast response.
Solution Approach 2:
The patent replaces the mechanical/electrical current monitoring approach with a voltage-based detection method. Instead of directly measuring the current through the high-side transistor, the system uses voltage detection at the transistor junction, which can be measured more accurately and with faster response time by standard voltage sensing circuits.
2Speed
If the switching cycle is shortened to increase switching frequency, then the power supply can respond faster to load changes, but switching losses increase
Solution Approach 1:
The patent implements dynamic switching cycle adjustment based on load conditions. The control circuit automatically extends the switching cycle when light load is detected, and uses shorter cycles when heavy load is present. This dynamic adaptation allows the power supply to respond quickly to load changes while minimizing switching losses during light load operation, optimizing both response speed and energy efficiency across different operating conditions.
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 high sensitivity and fast response in detecting light loads, reducing current consumption, and prolonging the switching cycle to minimize switching losses, thereby enhancing power supply efficiency and accuracy.
Implementation Method 1
an inductor disposed between a junction coupling the first and second switches and an output terminal from which an output voltage is output
Data Source
AI summary
A power supply includes a first switch and a second switch coupled in series between an input voltage terminal to which an input voltage is applied and a reference voltage terminal to which a reference voltage lower than the input voltage is applied, an inductor disposed between a junction coupling the first and second switches and an output terminal from which an output voltage is output, and a controller controlling the first and second switches to be alternately switched at a given switching cycle depending on an error of the output voltage with respect to a target voltage, wherein the controller changes the switching cycle from a first cycle to a second cycle longer than the first cycle, depending on a voltage at the junction when the second switch is in a turned-on state.