High-Side Driving Circuit for Slow Bootstrap Power-On
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Solution Overview
Problem
Existing driving circuits for high-voltage chips face issues with mistaken turn-on of pull-up high-voltage power transistors due to insufficient driving capability, particularly during the slow rise of bootstrap voltage, leading to potential transistor burnout.
Innovation Solution
The proposed driving circuit incorporates a high-side drive circuit with a mirror current source, MOS transistors, and an equivalent diode component to quickly regulate the auxiliary power terminal voltage, ensuring sufficient voltage is provided to the high-side pull-down circuit, even during slow power-on conditions, and utilizes a single-transistor operational amplifier for enhanced bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bootstrap voltage rises slowly during power-on, then the power supply voltage for the high-side drive circuit increases gradually, but the driving capability of the high-side pull-down circuit becomes insufficient, leading to potential mistaken turn-on of the pull-up transistor
Solution Approach 1:
The patent introduces an auxiliary power terminal that is activated before the main bootstrap voltage stabilizes. This auxiliary terminal provides preliminary power to the high-side pull-down circuit, ensuring it has sufficient driving capability from the very beginning of the power-on process, before the main bootstrap capacitor is fully charged.
Solution Approach 2:
The auxiliary power terminal acts as an intermediary power supply between the initial power-on state and the fully charged bootstrap state. It bridges the gap during the transition period when the main bootstrap voltage is insufficient, providing the necessary intermediate power level to maintain proper circuit operation.
2Device complexity
If the high-side drive circuit is powered directly from the bootstrap voltage terminal, then the circuit structure is simple, but the driving capability is insufficient when bootstrap voltage is low or rising slowly
Solution Approach 1:
The power supply function is segmented into two independent sources: the main bootstrap voltage terminal for normal operation and the auxiliary power terminal for startup assistance. This segmentation allows each power source to be optimized for its specific function while working together to ensure reliable operation throughout the entire power-on sequence.
Solution Approach 2:
The auxiliary power terminal provides preliminary power to the high-side pull-down circuit before the main bootstrap voltage is sufficient. This preliminary action ensures the pull-down circuit is fully operational and capable of preventing mistaken turn-on before the main power source takes over.
Data Source
AI summary
The present invention provides a driving circuit for a driving hip. The driving circuit includes a bootstrap circuit with a bootstrap voltage terminal. A power terminal of a high-voltage driving circuit is connected to the bootstrap voltage terminal, and a ground terminal of the high-voltage driving circuit is connected to a regulating terminal. A high-side drive circuit includes a high-side pull-up circuit and a high-side pull-down circuit. The driving circuit includes: an auxiliary power terminal; a mirror current source an input terminal of the mirror current source being connected to the bootstrap voltage terminal; a first MOS transistor; a second MOS transistor an equivalent diode component, an output terminal of the second MOS transistor being connected to the regulating terminal through the equivalent diode component; and an equivalent resistance component, the gate of the first MOS transistor being connected to the regulating terminal through the equivalent resistance component.