Over-Current Protection Circuit with Temperature Compensation
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Solution Overview
Problem
Conventional over-current protection circuits in drivers are prone to misoperation due to offset variations in sense voltage caused by temperature and voltage differences, leading to incorrect detection of over-current conditions.
Innovation Solution
An over-current protection circuit with a voltage generating unit that produces a reference voltage with an offset dependent on temperature and voltage, and a comparing unit that adjusts this offset to match the sense voltage, ensuring accurate comparison and preventing misoperation by compensating for temperature and voltage-induced variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional over-current protection circuit compares sense voltage with a fixed reference voltage, then the circuit structure is simple, but the detection accuracy deteriorates due to offset variations in sense voltage caused by temperature and voltage differences
Solution Approach 1:
The reference voltage is changed from a fixed value to a variable value that dynamically adjusts with temperature and voltage conditions. The voltage generating unit modifies the reference voltage parameters based on detected temperature and voltage differences, ensuring the reference voltage tracks the sense voltage offset variations, thereby maintaining accurate over-current detection across different operating conditions
Solution Approach 2:
The system implements feedback by detecting temperature and voltage difference parameters, then using this information to adjust the reference voltage through the voltage generating unit. This closed-loop feedback mechanism ensures the reference voltage automatically compensates for sense voltage offset variations, resolving the contradiction between simple circuit structure and accurate detection
2Measurement precision
If the reference voltage is made variable to compensate for sense voltage offset, then the detection accuracy is improved, but the device complexity increases due to additional voltage generating components
Solution Approach 1:
The voltage generating unit is designed to perform multiple functions: generating the reference voltage, adjusting it based on temperature variations, and compensating for voltage difference effects. By consolidating these functions into a single multi-functional unit, the circuit achieves accurate detection while minimizing the increase in overall device complexity
Solution Approach 2:
The temperature detection function and reference voltage generation function are merged into an integrated system where the voltage generating unit directly uses temperature detection results to adjust the reference voltage. This merging eliminates the need for separate compensation circuits, achieving accurate detection with minimal additional complexity
Data Source
AI summary
An over-current protection circuit includes a voltage generating unit and a comparing unit. The voltage generating unit is configured for receiving a first voltage and generating a reference voltage. The reference voltage has an offset positively dependent on temperature and negatively dependent on the first voltage, and the offset of the reference voltage varies along with another offset varying within a sense voltage sensed by the over-current protection circuit. The comparing unit is configured for comparing the reference voltage with the sense voltage to output a control signal for de-asserting the sense voltage when the sense voltage is correlated to an over-current condition of the sense voltage exceeding the reference voltage. A driver is also disclosed herein.