Isolated Gate Driver Thermal Monitoring With Pulse-Train Fault Reporting
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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 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 pulse train signals to communicate thermal fault information across an isolation barrier, and a method to reduce power consumption by disabling unused temperature sense pins and inverting PWM signals to minimize power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant temperature sensing is implemented, then thermal monitoring reliability is improved, but power consumption increases
Solution Approach 1:
The gate driver dynamically adjusts its operating mode based on temperature conditions. When the transistor temperature exceeds a threshold, the driver transitions to a high-reliability mode with active temperature monitoring and pulse train signal generation. When temperatures are normal, it operates in a low-power mode, disabling unnecessary monitoring functions to reduce power consumption while maintaining adequate thermal safety.
Solution Approach 2:
The system changes operational parameters based on temperature levels. The temperature sense circuit modifies its monitoring activity and the transceiver adjusts signal transmission parameters dynamically. This allows the system to maintain reliable thermal monitoring when needed while reducing power consumption during normal operating conditions by adjusting monitoring frequency and signal transmission duty cycle.
2Adaptability or versatility
If multiple temperature sense pins are enabled, then temperature monitoring capability is improved, but device complexity increases
Solution Approach 1:
The temperature sense pins serve multiple functions: they can monitor transistor temperature, indicate fault conditions, and provide ready signals. The same hardware infrastructure (sense pins, comparators, transceiver) is used for both temperature monitoring and fault communication, eliminating the need for separate dedicated circuits and reducing overall device complexity while maintaining versatile temperature monitoring capability.
Solution Approach 2:
The patent combines temperature sensing, fault detection, and communication functions into a unified circuit architecture. The temperature sense pins are merged with the fault indication system, and the transceiver integrates both temperature data transmission and fault signal communication. This consolidation reduces the number of separate components and simplifies the overall device structure while maintaining comprehensive monitoring capability.
3Reliability
If continuous temperature monitoring is performed, then thermal fault detection is improved, but power consumption increases
Solution Approach 1:
Instead of continuous monitoring, the gate driver performs temperature checks periodically at critical transition points in the switching cycle. The temperature sense circuit is activated during specific phases when thermal conditions are most critical, and the transceiver transmits pulse train signals periodically rather than continuously. This periodic operation maintains effective thermal fault detection while significantly reducing average power consumption compared to continuous monitoring.
Solution Approach 2:
The system performs preliminary temperature assessment before full monitoring activation. The gate driver initially checks temperature conditions and only activates continuous or high-frequency monitoring when threshold conditions are approached or exceeded. This preliminary check prevents unnecessary continuous operation of power-consuming monitoring circuits while ensuring thermal faults are detected when they become critical.
Data Source
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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.