Non-isolated DC/DC Converter Bootstrap Voltage Generation
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Solution Overview
Problem
The existing non-isolated DC/DC converters have a restricted lower limit for the output voltage setting due to the gate threshold voltage of the switching transistor, limiting the ability to generate low output voltages.
Innovation Solution
Incorporating a step-up circuit and a controller with a ground connected to the switching transistor, which generates a power supply voltage higher than the output voltage using a step-up pulse, allowing for the lowering of the output voltage setting without being restricted by the gate threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a non-isolated DC/DC converter uses a switching transistor with ground connected to source, then the converter structure is simple and compact, but the output voltage cannot be set below the gate threshold voltage of the switching transistor
Solution Approach 1:
The patent introduces a bootstrap circuit as an intermediary component between the switching transistor and the controller. This bootstrap circuit includes a bootstrap capacitor and bootstrap diode that generate a boosted voltage to drive the gate of the switching transistor. This intermediary mechanism allows the controller to operate with its ground reference while enabling the switching transistor to achieve sufficient gate-drive voltage, thereby resolving the contradiction between simple structure and extended voltage range.
2Ease of manufacture
If the ground of the controller is connected to the source of the switching transistor, then the controller and switching transistor can be integrated closely, but the power supply voltage of the controller becomes dependent on the output voltage which limits low voltage operation
Solution Approach 1:
The patent segments the voltage supply paths by introducing a separate bootstrap voltage generation system. The controller's power supply is divided into two independent sources: the main power supply connected to the input voltage, and the bootstrap power supply generated by the bootstrap circuit from the switching transistor's drain voltage. This segmentation allows the controller to maintain stable operation independent of the low output voltage, while still being closely integrated with the switching transistor for ease of manufacture.
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
This configuration enables the arbitrary setting of the output voltage below the gate threshold voltage, providing flexibility in voltage regulation and improving the capability to generate low output voltages.
Implementation Method 1
The switching transistor M1 is an N-channel metal oxide semiconductor field effect transistor (MOSFET)
Implementation Method 2
The buck converter 202 includes a switching transistor M1, an inductor L1, a rectifier diode D1, and an output capacitor C1
Implementation Method 3
an output capacitor C1
Implementation Method 4
a rectifier diode D1
Data Source
AI summary
A buck converter includes a switching transistor. A switching line connected to a source of the switching transistor is connected to a ground of a controller. The controller drives the switching transistor and generates a step-up pulse. The step-up circuit receives an output voltage VOUT of a DC/DC converter and generates a power supply voltage VBOOST of the controller using the step-up pulse.