Power Transistor Drain Temperature Sensing Across Voltage Domains
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Solution Overview
Problem
Existing circuits for determining the temperature of transistors are not precise and fast enough, particularly for power transistors that generate significant heat, which can cause damage if not managed effectively.
Innovation Solution
A circuit configuration that includes a first transistor with a thermistor or diode connected to its drain, coupled with a chip that generates a voltage representing the transistor's temperature, utilizing a level shifter and a floating supply to a different voltage domain, and a second circuit to a different voltage domain, and a third circuit to generate a control signal based on this voltage, with a floating supply and a level shifter to convert the signal to a logic level suitable for lower supply voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a circuit is configured to measure the temperature of the transistor, then the temperature detection capability is provided, but the precision and speed of temperature determination are insufficient
Solution Approach 1:
The patent introduces a dedicated temperature sensing circuit as an intermediary component between the power transistor and the control system. This separate sensing circuit measures the voltage at the drain terminal, which correlates with transistor temperature, providing accurate temperature data without interfering with the transistor's primary power switching function. The sensing circuit acts as a mediator that translates physical temperature into electrical signals for processing.
Solution Approach 2:
The patent divides the temperature measurement function into a separate, dedicated circuit module rather than integrating it into the main power transistor circuit. The temperature sensing circuit includes its own voltage measurement, signal processing, and threshold comparison components, segmented from the power management circuitry. This segmentation allows the sensing circuit to be optimized specifically for temperature measurement precision while the main circuit handles power switching.
2Speed
If existing temperature measurement circuits are used, then temperature monitoring is provided, but the response speed is too slow to prevent damage
Solution Approach 1:
The patent implements preliminary temperature monitoring by continuously measuring the voltage at the drain terminal, which serves as an early indicator of temperature rise. The sensing circuit is designed to detect temperature trends before they reach dangerous levels, allowing the control system to take preventive action. The circuit monitors voltage variations that precede critical temperature conditions, enabling proactive thermal management.
Solution Approach 2:
The patent establishes a feedback loop where the temperature sensing circuit continuously monitors the transistor's thermal state and provides real-time information to the control system. When the measured temperature or voltage indicates approaching thermal limits, the feedback mechanism triggers control actions to reduce power dissipation or activate cooling, creating a closed-loop system that responds dynamically to thermal conditions.
3Measurement precision
If the first terminal of the first circuit is connected to the drain of the first transistor, then the temperature measurement is enabled, but the circuit complexity increases
Solution Approach 1:
The patent leverages the existing drain terminal of the power transistor, which already exists as part of the transistor structure, to serve dual purposes: both power switching and temperature sensing. By connecting the temperature sensing circuit to the drain terminal, the same physical point is used for both the transistor's primary function and the temperature measurement function, eliminating the need for separate sensing terminals or additional connection points.
Solution Approach 2:
The temperature sensing circuit uses the transistor's own operating conditions (voltage at the drain terminal) as the measurement parameter. The circuit measures the voltage that naturally exists during transistor operation, rather than requiring separate excitation signals or additional components. The transistor essentially provides its own temperature information through its electrical characteristics during normal operation.
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 solution provides precise and fast temperature detection, allowing for quicker response to overheating conditions and preventing damage to transistors and surrounding components.
Implementation Method 1
the first circuit comprises a thermistor, the first terminal being one of the terminals of the thermistor
Implementation Method 2
the first circuit comprises a diode, the first terminal being one of the terminals of the diode
Data Source
AI summary
The present disclosure relates to a device comprising a first transistor and a first circuit comprising first and second terminals, the first circuit being configured to generate a first voltage representing the temperature of the first transistor, a first terminal of the first circuit being coupled to the drain of the first transistor.