Bootstrap Capacitor Charging Circuit With Fault Current Limiting
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
DC-to-DC converters face reliability and safety issues due to uncontrolled current flow through bootstrap capacitors during faults, such as short circuits, leading to excessive power dissipation and potential damage to integrated circuit packages.
Innovation Solution
A current-limited bootstrap charging circuit is introduced, which includes a current limiting circuit and a bootstrap capacitor charging circuit, capable of limiting current flow during faults while maintaining normal operation under nominal conditions, ensuring reliable and safe operation by preventing excessive power dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bootstrap capacitor charging circuit is provided to assure reliable operation of the high-side transistor, then the high-side transistor can be reliably operated, but excessive current may flow through the charging circuit during faults such as short circuits, leading to excessive power dissipation and potential damage to the integrated circuit package
Solution Approach 1:
The patent applies preliminary anti-action by incorporating a current limiting circuit that proactively restricts maximum current flow through the bootstrap capacitor charging circuit before excessive current can cause damage. The circuit establishes a predetermined current limit threshold that prevents harmful current excursions during fault conditions such as short circuits, thereby protecting the integrated circuit package while maintaining reliable operation of the high-side transistor during normal operation.
2Object-affected harmful factors
If current flow is limited during faults to prevent damage, then power dissipation is controlled, but the charging circuit must be designed to handle both normal operation and fault conditions
Solution Approach 1:
The patent employs an intermediary approach by introducing a current limiting circuit as a mediating component between the voltage source and the bootstrap capacitor charging circuit. This intermediary circuit selectively controls current flow based on operating conditions, allowing the system to maintain simple operation during normal conditions while automatically activating current limiting protection during fault conditions, thus managing complexity through conditional operation rather than requiring the entire system to be designed for worst-case scenarios.
Data Source
AI summary
According to some aspects, a circuit, such as an integrated circuit, comprises a bootstrap capacitor terminal, a bootstrap capacitor charging circuit coupled to the bootstrap capacitor terminal; and a bootstrap capacitor charging current limiting circuit coupled to the bootstrap capacitor charging circuit. According to some aspects, the circuit comprises a capacitor terminal, a capacitor charging transistor coupled to the capacitor terminal, a capacitor charging current sensing transistor coupled to the capacitor charging transistor, a current programming transistor coupled to the capacitor charging current sensing transistor; and a capacitor current limiting transistor coupled to the capacitor charging current sensing transistor, to the current programming transistor, and to the capacitor charging transistor. According to some aspects, an apparatus comprises a memory storing instructions to cause a processor to instantiate bootstrap capacitor charging current limiting circuit features.