Integrated Bootstrap Driver Chip Parasitic Diode Charging
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Solution Overview
Problem
Conventional half-bridge driver circuits face issues with high costs, increased complexity, and reduced charging efficiency due to the use of external high-voltage bootstrap diodes, which also lead to electric leakage and decreased system reliability.
Innovation Solution
An integrated bootstrap high-voltage driver chip utilizing parasitic diodes and a bootstrap control circuit to manage charging, eliminating the need for external diodes and simplifying the circuit structure while improving charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external high-voltage bootstrap diode is used, then the bootstrap function is achieved, but the circuit complexity and cost increase
Solution Approach 1:
The patent merges the bootstrap diode function with the existing high-voltage level shift circuit by utilizing the body diode of the high-voltage NMOS transistor (M01) already present in the circuit. This eliminates the need for a separate external bootstrap diode, reducing circuit complexity and component count while maintaining the required bootstrap functionality.
Solution Approach 2:
The high-voltage NMOS transistor M01 serves multiple functions: it acts as the main high-voltage switch for the high-side channel and simultaneously provides the body diode that functions as the bootstrap diode. This multi-functionality reduces the total number of components needed in the circuit.
2Reliability
If an external high-voltage bootstrap diode is used, then the bootstrap function is achieved, but the charging efficiency decreases
Solution Approach 1:
By integrating the bootstrap diode function into the level shift circuit's existing high-voltage NMOS transistor, the patent eliminates the need for an external diode with its associated forward voltage drop. The body diode of the integrated transistor provides lower resistance and faster charging of the bootstrap capacitor, improving charging efficiency.
3Reliability
If an external high-voltage bootstrap diode is used, then the bootstrap function is achieved, but the chip area increases
Solution Approach 1:
The patent combines the bootstrap diode functionality with the existing high-voltage level shift circuit structure. The body diode of transistor M01, which is already necessary for the level shift operation, serves dual purposes as both the level shift element and the bootstrap diode, eliminating the need for additional external components and reducing overall chip area.
4Reliability
If an external high-voltage bootstrap diode is used, then the bootstrap function is achieved, but the manufacturing cost increases
Solution Approach 1:
By integrating the bootstrap diode function into the existing high-voltage level shift circuit using the body diode of transistor M01, the patent eliminates the need for separate external bootstrap diode components. This reduction in component count directly lowers assembly costs and simplifies the manufacturing process.
5Strength
If the withstand voltage of the diode is increased, then the high-voltage capability is improved, but the turning-on voltage drop increases
Solution Approach 1:
The patent utilizes the inherent body diode of the high-voltage NMOS transistor M01, which is designed to withstand high voltages. This body diode naturally provides the required high-voltage blocking capability while having lower forward voltage drop compared to discrete high-voltage diodes, as it is optimized for the specific application context.
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 reduces chip area and manufacturing costs, enhances charging speed, and is suitable for high-frequency applications by leveraging parasitic diodes within the chip, thus addressing the limitations of prior art.
Implementation Method 1
a parasitic diode, which is formed between a low-voltage area and a high-voltage area in the isolation structure
Data Source
AI summary
Parasitic high-voltage diodes implemented by integration technology in a high-voltage level shift circuit are used for charging a bootstrap capacitor CB, wherein a power supply end of the high voltage level shift circuit is a high-side floating power supply VB, and a reference ground is a floating voltage PGD that is controlled by a bootstrap control circuit. A first parasitic diode DB1 and a second parasitic diode DB2 are provided between the VB and the PGD. The bootstrap control circuit is controlled by a high-side signal and a low-side signal.