DC-DC Converter Slew-Rate Control for Wide Luminance Efficiency
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Solution Overview
Problem
Existing DC-DC converters face efficiency challenges when operating at both low and high luminance levels, as they often require increased passive elements or active area, leading to reduced conversion efficiency.
Innovation Solution
A DC-DC converter design that includes a first converter with an inductor and transistors, an input current sensor, and a controller that adjusts the inductor voltage slew rate based on the input current and a reference current, allowing for efficient operation without increasing passive or active components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a DC-DC converter is designed to respond to high driving current, then it can handle high luminance, but conversion efficiency is reduced when driven at low luminance with low driving current
Solution Approach 1:
The patent implements dynamic adjustment of the inductor voltage slew rate based on the sensed input current level. When input current is high, a higher slew rate is applied; when input current is low, a lower slew rate is applied. This dynamic adaptation allows the converter to optimize its performance for the current operating condition, maintaining high conversion efficiency across both high and low luminance ranges without requiring separate converters or increasing component count.
2Loss of energy
If the slew rate of inductor voltage is increased to improve low luminance efficiency, then conversion efficiency at low luminance improves, but electromagnetic interference and voltage ripple increase
Solution Approach 1:
The patent dynamically adjusts the slew rate of the inductor voltage based on the input current level. At low input current (low luminance), a lower slew rate is applied to reduce electromagnetic interference and voltage ripple while maintaining adequate conversion efficiency. At high input current (high luminance), a higher slew rate is applied to maintain efficiency. This dynamic adjustment resolves the contradiction by adapting the slew rate to the operating conditions rather than using a fixed high value.
Solution Approach 2:
The patent changes the slew rate parameter of the inductor voltage based on the operating conditions (input current level). By adjusting this critical parameter dynamically, the system optimizes conversion efficiency at low luminance while controlling electromagnetic interference and voltage ripple, rather than maintaining a constant high slew rate that would cause harmful effects.
3Loss of energy
If multiple passive elements or larger active area are used to improve efficiency, then conversion efficiency improves, but device complexity and area increase
Solution Approach 1:
The patent uses dynamic control of the inductor voltage slew rate through a controller that senses input current and adjusts the slew rate accordingly. This approach improves conversion efficiency across different operating conditions without adding passive elements like additional inductors or capacitors, and without increasing the active area of transistors. The efficiency improvement is achieved through intelligent control rather than hardware multiplication.
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
The proposed solution maintains high conversion efficiency across both low and high luminance levels without increasing the number of passive elements or the active area, thereby addressing the efficiency challenges faced by existing converters.
Implementation Method 1
a first inductor coupled between a first node and ground
Implementation Method 2
a first transistor coupled between an input terminal to which an input voltage is applied and a first node
Data Source
AI summary
A voltage converter includes an input voltage line; an inductor coupled to the input voltage line; transistors coupled to the inductor; an output voltage line coupled to at least one of the transistors; a current sensor coupled to at least one of the input voltage line, the inductor, or the output voltage line; and a comparator coupled between the current sensor and the transistors. A DC-DC converter may include a voltage converter having an inductor and a plurality of transistors and configured to convert an input voltage into a power voltage and output the power voltage to an output terminal, an input current sensor configured to sense the input current of the converter, and a controller configured to change the slew rate of an inductor voltage in response to the input current of the converter and a preset reference current.