Isolated Gate Driver Thermal Monitoring With Low-Power Fault Signaling
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Solution Overview
Problem
Existing power switching systems face challenges in maintaining a modest size, cost, and complexity while performing fault monitoring and thermal reporting functions, particularly in applications where redundant temperature sensing is not strictly required, leading to increased power consumption.
Innovation Solution
A power switching system with a gate driver that includes temperature sensors for both the power transistor and the gate driver, using a transceiver to communicate combined fault signals across an isolation barrier, and a method to reduce power consumption by disabling unused temperature sense pins and using pulse width modulation for efficient communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant temperature sensing is implemented for both gate driver and power transistor, then thermal monitoring reliability is improved, but power consumption increases
Solution Approach 1:
The gate driver dynamically adjusts its operation based on temperature conditions. The system activates comprehensive dual-sensor monitoring only when thermal conditions require it, and can reduce to single-sensor mode or disabled state when temperatures are within safe ranges, allowing the monitoring system to adapt its power consumption to actual thermal risks
Solution Approach 2:
The system changes operational parameters by switching between different temperature monitoring modes. It can toggle between using both gate driver and transistor temperature sensors, using only one sensor, or disabling temperature monitoring entirely based on system state, thereby optimizing the balance between monitoring reliability and power consumption
2Reliability
If multiple temperature sensors and fault monitoring circuits are included, then fault detection capability is improved, but device complexity increases
Solution Approach 1:
The temperature sense circuit is designed to serve multiple functions: it can monitor both gate driver temperature and power transistor temperature, generate fault signals for protection, and provide thermal information for system optimization. This multi-functional design reduces the need for separate dedicated circuits for each function, thereby reducing overall device complexity while maintaining comprehensive fault detection capability
Solution Approach 2:
The patent combines the temperature sensing, fault detection, and protection logic into an integrated gate driver circuit. By merging these functions into a unified design rather than separate modules, the system achieves comprehensive fault detection without proportionally increasing device complexity
3Reliability
If continuous temperature monitoring is performed, then thermal safety is improved, but power consumption increases
Solution Approach 1:
Instead of continuous monitoring, the system employs periodic temperature sampling at strategically chosen moments in the switching cycle. Temperature measurements are taken at intervals that capture thermal trends without requiring constant sensor activation, thereby maintaining thermal safety while significantly reducing the average power consumption of the temperature monitoring system
Data Source
AI summary
A galvanically isolated gate driver for a power transistor is disclosed. The gate driver provides various temperature protection features that are enabled by (i) diagnostic circuitry to generate fault signals and monitoring signals, (ii) signal processing to enable communication over a shared communication channel across an isolation barrier, (iii) signal processing to reduce operating current needed for real-time thermal monitoring, and (iv) a disable circuit for unused temperature sensing pins.