Real-Time Short-Circuit Detection Circuit for Switched-Mode Systems

The patent implements preliminary action by detecting short-circuit conditions before over-limit current events occur. The detection circuit monitors voltage discrepancies at switching nodes in real-time during the switching cycle, enabling early identification of short-circuit conditions. This allows the system to take preventive action before damage occurs, resolving the contradiction by improving reliability through early detection while maintaining manageable circuit complexity through efficient real-time monitoring.

The patent uses a scaled-down replica of the power stage and load as a reference model. By creating a simplified copy of the actual circuit topology and comparing its behavior against the real system, the detection circuit can identify anomalies without requiring complex absolute measurements. This copying approach enables accurate short-circuit detection while keeping the detection circuit relatively simple, as the replica serves as a built-in reference that eliminates the need for external calibration standards.

The patent implements feedback by continuously comparing the actual switching node voltages against the scaled-down replica voltages and using the comparison results to detect short-circuit conditions. The synchronized comparator provides real-time feedback about voltage discrepancies, enabling the system to identify and respond to short-circuits before they cause damage. This feedback mechanism achieves reliable damage prevention while managing circuit complexity through efficient use of the comparator output for control decisions.

The detection circuit operates periodically synchronized with the switching cycle of the class-D audio amplifier. By performing comparisons at specific phases of the switching cycle and using adaptive clocking, the system achieves real-time monitoring without requiring continuous complex processing. This periodic action aligned with the natural operating rhythm of the amplifier enables reliable detection while reducing the burden on the comparator circuit, thus managing complexity.

The patent creates a scaled-down replica of the power stage and load that accurately mirrors the electrical characteristics of the actual circuit. This replica serves as a dynamic reference that automatically adapts to load impedance variations. By comparing the actual system behavior against this living reference model, the detection circuit achieves high measurement precision for short-circuit detection without requiring complex algorithms to compensate for impedance changes. The replica inherently accounts for load variability, simplifying the detection strategy.

The patent uses parameter changes by scaling down the power stage and load parameters to create a manageable reference model. This scaling transformation allows the system to maintain accurate electrical behavior relationships while working with practical circuit values. The scaled parameters enable precise comparison and detection without requiring the detection circuit to handle the full power levels and impedance ranges of the actual system, thus achieving high measurement precision with reduced complexity.