Transistor Short-Circuit Detection Using Surface Temperature Rise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional overcurrent detection circuitry struggles to accurately detect short circuits during transistor switching due to transient issues, potentially leading to transistor damage from prolonged or false detection.
Innovation Solution
A short-circuit detection circuit that estimates the surface temperature of switching transistors using a sense resistor, amplifier, and resistor-capacitor ladder circuit, allowing for real-time detection of short circuits by converting current flow into a scaled current and measuring temperature rise, thereby preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional overcurrent detection circuitry is used to monitor current flow through transistors, then overcurrent conditions can be detected after switching settles, but the detection is too slow to protect against short circuits during switching transients
Solution Approach 1:
The patent replaces conventional electrical current measurement with thermal field measurement. By measuring the temperature rise of the transistor case (which correlates with internal die temperature) and using this thermal information to trigger protection, the system achieves faster detection during switching transients without being affected by electrical noise or transient current spikes that confound conventional electrical detection methods.
2Reliability
If the blanking time for overcurrent detection is extended to avoid false detection during switching, then false detection is reduced, but the protection time is too long allowing transistor damage
Solution Approach 1:
The patent substitutes thermal field measurement for electrical field measurement to resolve the timing contradiction. Thermal measurement provides a different timescale that is appropriate for detecting actual damage conditions without being confounded by fast electrical transients, thereby eliminating the need for lengthy blanking periods while maintaining detection accuracy.
3Measurement precision
If conventional electrical field measurement is used for overcurrent detection, then current flow can be monitored, but transient switching effects cause false detection or delayed detection
Solution Approach 1:
The patent replaces electrical field measurement with thermal field measurement. By measuring temperature rise of the transistor case and correlating this with internal die temperature, the system achieves reliable short circuit detection that is immune to the transient electrical switching effects that plague conventional electrical measurement methods.
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
Enables effective detection of short circuits during transistor switching, preventing damage by accurately identifying temperature thresholds and triggering protection measures.
Implementation Method 1
The sense resistor is coupled to the current terminal, and is configured to develop a sense voltage proportional to a current through the current terminal
Implementation Method 2
The amplifier is coupled to the sense resistor, and is configured to generate a scaled current proportional to the sense voltage
Implementation Method 3
The resistor-capacitor ladder is coupled to the amplifier, and is configured to generate a measurement voltage that represents a surface temperature rise due to the current through the current terminal
Data Source
AI summary
A short circuit detection circuit includes a current terminal, a sense resistor, an amplifier, and a resistor-capacitor ladder. The sense resistor is coupled to the current terminal, and is configured to develop a sense voltage proportional to a current through the current terminal. The amplifier is coupled to the sense resistor, and is configured to generate a scaled current proportional to the sense voltage. The resistor-capacitor ladder is coupled to the amplifier, and is configured to generate a measurement voltage that represents a surface temperature rise due to the current through the current terminal.