Class-D Driver Stage Short-Circuit Location Using Four Current Sensors
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Solution Overview
Problem
Existing Class-D driver stage topologies fail to effectively detect short circuits between specific nodes due to current flow bypassing the current sense resistor, making it difficult to identify and locate such faults.
Innovation Solution
Implement a system with four sensors coupled to each switch in the Class-D stage to measure sense currents or voltages, allowing detection of short circuits by analyzing the proportional relationships between these measurements to determine their presence and location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single current sense resistor is used in the Class-D driver stage, then the circuit complexity is reduced, but the ability to detect short circuits between specific nodes is lost because current flows predominantly through the short circuit path bypassing the sense resistor
Solution Approach 1:
The patent divides the single current sensing function into four separate sensing paths, each associated with a specific switch in the H-bridge configuration. Each switch has its own current sense resistor that measures current flowing through that specific switch, enabling localized fault detection while maintaining overall system functionality.
Solution Approach 2:
The patent introduces four individual current sense resistors as intermediary elements between the power switches and the detection circuitry. These resistors act as mediators that convert switch currents into measurable voltages, allowing the detection system to indirectly monitor switch conditions without directly interfering with the high-current power path.
2Measurement precision
If four current sensors are coupled to each switch in the Class-D stage, then the short circuit detection precision is improved, but the device complexity increases
Solution Approach 1:
The patent designs the current sensing circuitry with universal applicability across all four switches in the H-bridge. Each switch uses the same sensing topology and configuration, allowing the system to detect various fault conditions (short to ground, short to supply, cross-conduction) using a standardized approach. This multi-functional design enables a single detection mechanism to handle multiple types of faults.
Solution Approach 2:
The patent combines the four individual current sensor measurements into a unified detection system that analyzes the collective data to identify fault conditions. By merging the sensing functions and processing the combined information, the system achieves comprehensive short circuit detection capability while avoiding the need for four independent detection systems.
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 system accurately detects and locates short circuits in the Class-D stage, enhancing fault detection capabilities and preventing damage to the driver stage.
Implementation Method 1
a first sensor coupled to the first high-side switch and configured to sense a first sense current associated with the first high-side switch, such that an output current through a load coupled between the first output terminal and the second output terminal is proportional to the first sense current
Data Source
AI summary
A system may include a Class-D stage comprising a first high-side switch coupled between a supply voltage and a first output terminal of the Class-D stage, a second high-side switch coupled between the supply voltage and a second output terminal of the Class-D stage, a first low-side switch coupled between a ground voltage and the first output terminal, and a second low-side switch coupled between the ground voltage and the second output terminal. The system may also include current sensing circuitry comprising a plurality of sensors, each sensor configured to sense a current associated with a respective one of the first high-side switch, second high-side switch, first low-side switch, and second low-side switch. The system may also include short-circuit detection circuitry configured to determine a presence and a location of a short circuit in the Class-D stage based on the sensed currents.