Buck Converter PFM Control with Adaptive Current Thresholds
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Solution Overview
Problem
Existing pulse frequency modulation (PFM) switched-mode power supply buck converters have limitations in delivering a range of average current values without increasing start-up time or output voltage ripple amplitude.
Innovation Solution
A switched-mode power supply buck converter with a control circuit that adjusts the maximum value of current pulses in an inductive element based on the average current drawn, allowing for increased maximum average current delivery without extending start-up time or increasing output voltage ripples, by selecting between multiple predefined current values and using temporizations to control switch states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the maximum current pulse value is increased to deliver higher average current, then the maximum average current delivery capability is improved, but the start-up time increases
Solution Approach 1:
The patent applies dynamics by making the maximum current pulse value adjustable rather than fixed. The control circuit dynamically selects between a first maximum value and a second maximum value based on operating conditions, allowing the system to adapt its current delivery capability to match demand, thereby achieving high current delivery without permanently increasing start-up time
Solution Approach 2:
The patent changes the parameter of maximum current pulse value from a constant to a variable parameter. By switching between different maximum current values based on load conditions, the system can deliver higher average current when needed while maintaining lower current values during normal operation, thus avoiding increased start-up time
2Productivity
If the maximum current pulse value is increased to deliver higher average current, then the maximum average current delivery capability is improved, but the amplitude of output voltage ripples increases
Solution Approach 1:
The control circuit dynamically adjusts the maximum current pulse value based on load detection. By only increasing the maximum current when high average current delivery is actually required, the system avoids generating excessive voltage ripples during normal low-current operation, thus resolving the contradiction between current delivery capability and ripple amplitude
Solution Approach 2:
The patent changes the maximum current pulse value parameter from fixed to variable, switching between a first maximum value (lower) and a second maximum value (higher) based on detected load conditions. This parameter adaptation allows the system to deliver high average current when needed while maintaining low ripple amplitude during normal operation
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
Enables a broader range of average current delivery without increasing start-up time or output voltage ripple amplitude, improving the converter's operational flexibility and efficiency.
Implementation Method 1
energy is supplied to an inductive element during an energy accumulation phase and restored by the inductive element at the converter's output during an energy restoration phase
Data Source
AI summary
The present disclosure relates to a switched-mode Power Supply Buck Converter comprising: a switch connected between a node receiving a supply potential and an internal node; another switch connected between the internal node and a node receiving a reference potential; an inductive element coupling the internal node to an output node; and a control circuit controlling the switches so that current pulses in the inductive element have a maximum value selected from among at least a first value and a second value based on an average current drawn at the output node.