Power Transistor Overcurrent Detection During Idle-Mode Transients
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Solution Overview
Problem
Intelligent semiconductor switches face high power consumption in idle-mode due to inactive overcurrent protection, leaving them vulnerable to fast rising load current transients during mode transitions, which can harm the device.
Innovation Solution
An emergency overcurrent protection circuit is activated in idle-mode to quickly react to fast current transients, distinguishing between short circuits and normal load changes, ensuring the power transistor is protected during mode transitions with minimal power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the circuit operates in idle-mode with reduced power consumption, then power consumption is reduced, but overcurrent protection is inactive leaving the device vulnerable to fast current transients
Solution Approach 1:
The overcurrent protection is divided into two separate circuits: a first overcurrent protection circuit that operates during idle-mode with reduced power consumption, and a second overcurrent protection circuit that operates during active-mode with full protection capabilities. This segmentation allows the system to maintain appropriate protection levels while optimizing power consumption for each operational state.
Solution Approach 2:
The system dynamically switches between different protection modes based on the operational state. During idle-mode, the first protection circuit is active with lower power consumption. When a current threshold is exceeded, the system transitions to active-mode and the second protection circuit takes over, providing dynamic adaptation to protection requirements.
2Reliability
If the circuit transitions from idle-mode to active-mode, then full protection functions become available, but there is a transition time delay during which fast current transients can occur
Solution Approach 1:
The first overcurrent protection circuit is prepared and active in advance during idle-mode, monitoring current conditions before the full protection system is needed. This preliminary protection ensures that when fast current transients occur during mode transition, protection is already in place rather than waiting for the transition to complete.
Solution Approach 2:
The first overcurrent protection circuit acts as an intermediary during the transition period between idle-mode and active-mode. It provides bridging protection until the second overcurrent protection circuit becomes fully operational, ensuring continuous protection coverage without gaps during the mode transition.
3Reliability
If conventional overcurrent protection is used, then comprehensive protection is provided, but power consumption is relatively high making it unsuitable for idle-mode operation
Solution Approach 1:
The protection system is segmented into two distinct circuits with different power consumption characteristics. The first circuit is optimized for low power consumption during idle-mode, while the second circuit provides comprehensive protection during active-mode. This segmentation resolves the contradiction by providing appropriate protection levels matched to operational requirements.
Solution Approach 2:
Different quality levels of protection are applied to different operational states. During idle-mode, a simplified protection approach with lower power consumption is used. During active-mode, full comprehensive protection is activated. This local quality approach ensures that protection capability is optimized for each specific operational context.
Data Source
AI summary
In accordance with an embodiment, a circuit includes a power transistor connected between a supply terminal and an output terminal; a control circuit coupled to a control electrode of the power transistor and configured to apply a control current to the control electrode to turn the power transistor on or off; and an overcurrent protection circuit connected to the power transistor. The circuit is configured to operate in a first mode, in which some functions of the circuit are inactive to reduce power consumption, and in a second mode, in which all functions of the circuit are active. The overcurrent protection circuit is configured to: in response to the circuit being in the first mode and a sense signal indicative of a load current passing through the power transistor reaching a first threshold, cause the circuit to change from the first mode to the second mode.