Trim Circuit for Temperature Sensor Mismatch in Power Switches
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Solution Overview
Problem
Existing temperature sensor circuitry for power switch devices, such as MOSFETs, struggles to accurately sense temperature variations during high in-rush current conditions, leading to inadequate protection and potential overheating, as the safe operating area (SOA) limits are not effectively managed, especially when load conditions change over time.
Innovation Solution
The implementation of a temperature sensor circuitry that includes a first and second temperature sensor, along with a trim circuit, to compensate for mismatched temperature coefficients of sensing elements, converting voltage signals to current signals, and using a comparator for shutdown control, ensuring a consistent threshold across operating temperatures and reducing component count for efficient current mode operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature sensor circuitry is used to sense temperature during high in-rush current conditions, then thermal protection is provided, but measurement precision deteriorates due to mismatched temperature coefficients of sensing elements
Solution Approach 1:
The patent applies parameter changes by introducing trim circuits that adjust the temperature coefficient parameters of the sensing elements. The first trim circuit modifies the temperature coefficient of the first sensing element, while the second trim circuit modifies the temperature coefficient of the second sensing element, enabling precise matching between them to eliminate measurement errors during high in-rush current conditions
Solution Approach 2:
The patent implements feedback mechanisms where the temperature sensor circuitry continuously monitors the temperature difference between the power switch device and the control circuit. The trim circuits receive feedback signals and adjust their trimming parameters dynamically to maintain accurate temperature measurement despite varying operating conditions and in-rush current effects
2Adaptability or versatility
If voltage signals are converted to current signals for temperature sensing, then operating range under low power conditions is improved, but device complexity increases due to additional conversion circuits
Solution Approach 1:
The patent merges the voltage-to-current conversion function with the temperature sensing function into an integrated temperature sensor circuit. The conversion circuits are combined with the sensing elements and trim circuits in a unified architecture, reducing overall device complexity while maintaining the ability to operate across a wide range of power conditions
Solution Approach 2:
The patent introduces intermediate conversion circuits that act as mediators between the voltage-based sensing elements and the current-based output requirements. These intermediary circuits enable efficient signal transformation while being optimized to minimize their own complexity and power consumption
3Measurement precision
If trim circuits are added to compensate for temperature coefficient mismatch, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The trim circuits implement parameter changes by providing adjustable trimming parameters that can be programmed or calibrated to match the specific temperature coefficients of the sensing elements. This allows precise compensation for manufacturing variations while keeping the trim circuit architecture relatively simple and reusable across different device variants
Solution Approach 2:
The trim circuits are designed with dynamic adjustment capabilities, allowing the trimming parameters to be modified based on measured temperature coefficients. This dynamic approach enables the system to adapt to different sensing element characteristics without requiring completely different circuit designs for each variation
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
This solution provides accurate thermal sensing and shutdown control, ensuring power switch devices operate within safe limits, reducing energy accumulation during high in-rush currents and offering a low-cost, area-efficient design with improved operating range under low power conditions.
Implementation Method 1
a first voltage that varies based on a temperature of the power switch device... a second voltage that varies based on a temperature of a substrate
Data Source
AI summary
An example device includes a first temperature sensor configured to provide a first current signal indicative of a temperature of a first circuit based on a voltage of a first temperature sensing element. The first circuit includes a power switch device and the first temperature sensing element. A second temperature sensor is configured to provide a second current signal indicative of temperature of a second circuit based on a voltage of a second temperature sensing element. The second circuit includes the second temperature sensing element. A trim circuit is configured to trim current in at least one of the first temperature sensor or the second temperature sensor to compensate for mismatch between temperature coefficients of the first and second temperature sensing elements.