Power Converter Load Switch Fault Protection
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Solution Overview
Problem
Power converters face challenges in efficiently delivering power and protecting against over-voltage conditions, particularly in scenarios where a fault condition such as a drain-gate short occurs, leading to increased dissipation and potential damage to load switch components.
Innovation Solution
The implementation of a power converter with secondary-side control circuitry that monitors voltage drops across the load switch and triggers a control signal to limit the power converter's output, reducing power delivery and preventing damage by switching to a lower power mode when a fault condition is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power converter operates at high power to meet increasing demand, then power delivery capability is improved, but the risk of damage from fault conditions increases
Solution Approach 1:
The patent implements preliminary protective action by monitoring voltage drops across the load switch before catastrophic failure occurs. The control circuitry detects abnormal voltage drops that indicate fault conditions (such as drain-gate shorts) and preemptively limits power converter operation to prevent damage, allowing the system to operate at high power during normal conditions while maintaining reliability through early fault detection and response.
2Power
If the load switch is controlled to deliver high current to the load, then power delivery is improved, but dissipation and overheating increase
Solution Approach 1:
The patent employs feedback control by continuously monitoring the voltage drop across the load switch and using this information to regulate power converter operation. When the voltage drop exceeds a threshold indicating excessive dissipation or fault conditions, the control circuitry reduces power delivery to maintain safe operating levels, enabling high current delivery during normal operation while preventing overheating through real-time feedback-based power limiting.
3Reliability
If fault detection sensitivity is increased to detect early fault conditions, then protection capability is improved, but false triggering and operational disruptions increase
Solution Approach 1:
The patent optimizes detection parameters by setting the voltage drop threshold based on the specific characteristics of the load switch and operating conditions. This parameter optimization enables sensitive detection of actual fault conditions while minimizing false triggering during normal operation, maintaining both high reliability through accurate fault detection and operational stability by avoiding unnecessary power limitations.
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
An apparatus for delivering power to a load, which comprises a power converter that converts input power at a primary side to an output power and to a supply voltage to a secondary side. On the secondary side, a load switch is located on a current path to the load. A secondary-side control circuitry controls the load switch to operate in an ON mode in which current is provided to the load, and in response to a fault condition corresponding a voltage drop across the load switch exceeding a threshold value, activates circuitry on the secondary side. The circuitry, in response to the fault condition, causes the primary-side control circuitry to limit an extent to which the power converter is capable of supplying power.