Bootstrap Power Supply Circuit for DC/DC Converters
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Solution Overview
Problem
Existing DC/DC converters face challenges in maintaining stability and efficiency, particularly in reduced voltage states, due to limitations in the bootstrap power supply circuit's responsivity and the need for additional external components, which affect circuit area and cost.
Innovation Solution
A compact-size control circuit with a bootstrap power supply circuit that includes a variable impedance circuit controlled by an impedance controller, allowing for dynamic impedance adjustment to maintain constant voltage and reduce current consumption, eliminating the need for external capacitors and enhancing stability across varying voltage states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional bootstrap power supply circuit is used, then the circuit can operate, but it requires external capacitors and has low responsivity in feedback operations
Solution Approach 1:
The patent merges the bootstrap capacitor function with an internal capacitor within the control circuit integrated circuit. Instead of requiring an external bootstrap capacitor, the circuit integrates a capacitor directly inside the IC, combining multiple functions into a single device. This eliminates the need for external capacitors while maintaining the bootstrap function and improving feedback responsivity.
Solution Approach 2:
The control circuit IC is designed to perform multiple functions: it provides the bootstrap power supply function, includes an internal capacitor for voltage stabilization, and integrates the control logic for the DC/DC converter. This multi-functional design eliminates the need for separate external components while improving overall circuit performance.
2Area of stationary object
If the bootstrap power supply circuit is simplified, then the circuit area is reduced, but stability in reduced voltage states deteriorates
Solution Approach 1:
The patent combines the voltage stabilization function with the bootstrap power supply circuit by integrating a capacitor internally within the control circuit IC. This merged design provides stability in reduced voltage states without requiring additional external components, thus maintaining reliability while reducing circuit area.
3Device complexity
If external capacitors are eliminated, then cost and circuit area are reduced, but maintaining constant voltage becomes difficult
Solution Approach 1:
The patent integrates a capacitor internally within the control circuit IC to perform voltage stabilization. This internal capacitor replaces the function of external capacitors, maintaining constant voltage capability while eliminating external components and reducing overall circuit complexity.
Solution Approach 2:
The control circuit IC is designed as a multi-functional integrated device that provides both the control logic and the voltage stabilization function through its internal capacitor. This universal design maintains constant voltage capability without requiring separate external components.
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 solution provides high responsivity and stability in feedback operations, maintaining constant voltage even in reduced voltage states while reducing power consumption and eliminating the need for external components, resulting in a more compact and cost-effective design.
Implementation Method 1
a bootstrap capacitor C2, arranged in the form of an external component between the LX terminal and a bootstrap (BST) terminal
Implementation Method 2
a rectifier element 212, arranged between the BST terminal and an output of the bootstrap power supply circuit 220R
Data Source
AI summary
A bootstrap power supply circuit generates a constant voltage VCCBST for charging a bootstrap capacitor. An output transistor is configured as an N-channel MOSFET arranged such that its drain is connected to an input line and such that its source is connected to an output line. A constant voltage circuit connected to the gate of the output transistor stabilizes the gate voltage VG to a constant value. A variable impedance circuit is arranged between the input line and the gate of the output transistor, in order to provide a variable impedance. An impedance controller controls the impedance of the variable impedance circuit according to the state of a step-down DC/DC converter.