Switched-mode power supply switch resizing
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Solution Overview
Problem
Switched-mode power supplies, such as boost converters, face efficiency decreases due to higher parasitic capacitance and increased power consumption when sized for maximum load current, particularly at low current outputs.
Innovation Solution
Implementing a power converter with a switch composed of multiple transistors connected in parallel, where the driver module selectively drives the transistors based on output states, allowing for a larger periphery at high currents and reducing switch size at low currents to minimize parasitic capacitance, thereby enhancing efficiency across a wider dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the switch is sized for maximum load current capability, then the power supply can handle high current outputs, but parasitic capacitance increases and efficiency decreases at low current outputs
Solution Approach 1:
The switch is divided into multiple parallel transistors (first switch transistor and second switch transistor) that can be independently controlled. This segmentation allows the power supply to activate only the necessary number of transistors based on load conditions, reducing parasitic capacitance at low currents while maintaining maximum current capability when all transistors are activated together.
2Power
If the switch is sized for maximum load current capability, then high current handling is achieved, but drive signal requirements and power consumption increase due to higher parasitics
Solution Approach 1:
By segmenting the switch into multiple independently controllable transistors, the system can activate only the necessary number of devices based on load requirements. This reduces the total parasitic capacitance that must be charged and discharged during switching, thereby reducing drive signal power consumption while maintaining the capability to handle maximum load current when all transistors are activated.
3Device complexity
If a single switch is used, then the circuit is simple, but efficiency cannot be optimized across different load conditions
Solution Approach 1:
The circuit transitions from a static single-switch design to a dynamic multi-transistor configuration where the active number of transistors changes based on load conditions. The driver module dynamically selects which transistors to activate, optimizing efficiency for different operating points while maintaining relatively simple circuit architecture through systematic control.
Data Source
AI summary
Switched-mode power supply with switch resizing. A power converter can include an inductor coupled between an input node and an intermediate node, a semiconductor device coupled between the intermediate node and an output node, and a plurality of drive transistors. Each one of the plurality of drive transistors can have a drain coupled to the intermediate node and a source coupled to a ground potential.