Semiconductor Overcurrent Protection with Delayed Activation
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Solution Overview
Problem
Semiconductor devices face challenges in protecting against over-heating during both start-up and normal operation, as current limitation or over-current protection mechanisms either allow excessive current during high inrush periods or trigger false shut-offs, necessitating complex temperature sensors and higher costs.
Innovation Solution
A semiconductor device with an over-current detection feature that includes a current sensor arrangement and evaluation circuit to measure load current, allowing a delay period before triggering over-current protection, enabling high inrush current handling during start-up and effective protection during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If current limitation to a predefined maximum current is used, then high inrush current during start-up is handled, but the maximum current may be too high to avoid over-heating during normal operation
Solution Approach 1:
The patent applies the preliminary action principle by implementing a delay mechanism that temporarily disables over-current protection during the start-up period when inrush current is expected. The control circuit includes a delay element that prevents over-current shutdown for a predetermined time after power-on, allowing high inrush current to flow without triggering protection. After the delay period expires, the over-current protection becomes active for normal operation, thus resolving the contradiction between handling start-up inrush current and preventing over-heating during steady-state operation.
2Object-affected harmful factors
If over-current protection with a low threshold is used, then over-heating is avoided, but high inrush current during start-up triggers false shut-off
Solution Approach 1:
The patent implements preliminary action by pre-configuring a delay mechanism that anticipates the inrush current event during start-up. The control circuit is designed to automatically suppress over-current protection signals during the initial period after power-on, before the delay timer expires. This preliminary suppression prevents false shut-off during normal inrush current events while maintaining the low over-current threshold for actual fault conditions during normal operation.
3Reliability
If temperature sensors are added to handle both start-up and normal operation protection, then sufficient protection is provided, but device complexity and cost increase
Solution Approach 1:
The patent applies the self-service principle by implementing a time-based delay mechanism within the existing control circuit that automatically differentiates between start-up inrush current and abnormal over-current conditions. The control circuit uses an internal delay timer that is triggered on power-on and automatically disables over-current protection during the delay period without requiring external temperature sensors or additional protection circuits. This self-service approach provides comprehensive protection for both start-up and normal operation phases using only the existing current sensor and control logic.
Data Source
AI summary
A semiconductor device with an over-current detection feature is disclosed. According to an example of the invention the device includes: a semiconductor chip including a load current path that conducts a load current in response to an input signal activating the load current flow. A current sensor arrangement provides a measurement signal representing the load current. An evaluation circuit is configured to compare the measurement signal with a first threshold and to signal an over-current when the measurement signal exceeds the first threshold after a delay time period starting from the activation of the load current flow has elapsed.