Self-Biased Buck Regulator Eliminating Bootstrap Diodes
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Solution Overview
Problem
Existing self-biased non-isolated buck regulators face challenges in achieving low output voltages efficiently due to the need for high-voltage bootstrap diodes and short conduction times, which increase cost and complexity, and limit switching frequency and inductor size.
Innovation Solution
A self-biased non-isolated buck regulator design incorporating a high-voltage switch, a low-voltage switch, an inductor, a high-voltage rectifier diode, a low-voltage diode, and a capacitor, with a comparator and PWM latch configuration to control current and voltage, allowing for efficient operation at high switching frequencies and flexible output voltage generation without high-voltage bootstrap diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a high-voltage bootstrap diode is used in the buck regulator, then the regulator can operate with high-side switch control, but the cost and complexity of the regulator increases
Solution Approach 1:
The patent extracts and removes the high-voltage bootstrap diode from the regulator circuit. Instead of using a high-voltage diode for bootstrap operation, the invention uses a low-voltage diode combined with a flying capacitor to generate the necessary bootstrap voltage, thereby eliminating the need for expensive high-voltage diodes and reducing overall circuit complexity
Solution Approach 2:
The patent introduces a flying capacitor as an intermediary element that works with a low-voltage diode to generate the bootstrap voltage required for high-side switch control. This intermediary approach allows the system to achieve high-side switch functionality without directly using high-voltage diodes, thus reducing cost and complexity
2Adaptability or versatility
If the output voltage is set to low values (3.3V or 5V), then the regulator meets typical application requirements, but the conduction time of the switch becomes very short making peak current control difficult
Solution Approach 1:
The patent implements a feedback mechanism using a current sense element and comparator that monitors the current through the low-voltage switch. This feedback allows the control circuit to accurately detect and regulate peak current even during the very short conduction periods required for low output voltages, making current control feasible across a wide voltage range
Solution Approach 2:
The patent uses dynamic control of the low-voltage switch conduction time based on the required output voltage. By dynamically adjusting the on-time of the low-voltage switch and using feedback-controlled peak current detection, the system can adapt to different output voltage requirements while maintaining proper current control
3Volume of moving object
If the switching frequency is increased to reduce inductor size, then the regulator efficiency improves, but the peak current in switches becomes harder to control
Solution Approach 1:
The patent employs feedback-based peak current detection using a current sense element and comparator that works effectively at high switching frequencies. This feedback mechanism allows accurate peak current control even when the switch conduction time is extremely short, enabling the use of higher switching frequencies to reduce inductor size
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 enables efficient operation at high switching frequencies and flexible output voltage generation, reducing costs and complexity by eliminating the need for high-voltage bootstrap diodes and improving control over peak current in the switches.
Implementation Method 1
an inductor 104
Implementation Method 2
an output filter capacitor 105
Implementation Method 3
a high-voltage rectifier diode 103
Data Source
AI summary
A self-biased non-isolated buck regulator is provided. The regulator may include a first input terminal and a second input terminal, a high-voltage switch coupled to the first input terminal, a low-voltage switch coupled to the high-voltage switch, an inductor having a first terminal coupled to the high-voltage switch and the first low-voltage switch, a high-voltage rectifier diode coupled between the first low-voltage switch and the second input terminal, a second low-voltage switch coupled to the first low-voltage switch and the high-voltage rectifier diode, and a capacitor having a first terminal coupled to the first terminal of the inductor, and a second terminal coupled to the second low-voltage switch.