Output Transistor Retry Control With Continuous Overcurrent Flag
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Solution Overview
Problem
Conventional overcurrent protection systems in semiconductor integrated circuits fail to provide external indication of overcurrent states and retry operations, making it difficult for external devices to determine circuit abnormalities.
Innovation Solution
A semiconductor integrated circuit device with an overcurrent protection circuit that includes a retry function to intermittently cut and resume output current, accompanied by an error flag terminal to continuously signal an abnormal state during retry operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If an error flag terminal is provided to indicate overcurrent state and retry operation, then external devices can determine circuit abnormalities, but the error flag signal fluctuates between normal and abnormal states making it difficult to use
Solution Approach 1:
The patent applies the Dynamics principle by transitioning the error flag from a static binary state to a dynamic multi-state system. The error flag output circuit generates three distinct states (normal, overcurrent detection, retry operation) based on the operational phase, allowing external devices to distinguish between different abnormal conditions. This dynamic state differentiation resolves the ambiguity of fluctuating signals by providing meaningful context for each state transition.
Solution Approach 2:
The patent introduces an intermediary error flag output circuit that mediates between the internal retry operation and external devices. This intermediary translates internal circuit states into externally meaningful signals, acting as a buffer that converts complex internal operations into simple, interpretable flag states. The error flag circuit serves as the mediator that bridges the gap between internal overcurrent protection mechanisms and external system monitoring.
2Reliability
If retry operation is performed to automatically resume steady state, then device can recover from overcurrent conditions, but continuous short circuit keeps temperature at 100°C or higher causing device failure
Solution Approach 1:
The patent implements periodic action through the retry operation mechanism that intermittently attempts to resume steady state operation. The control circuit periodically tries to restore normal operation after overcurrent detection, creating a cyclic pattern of detection, interruption, and attempted recovery. This periodic retry approach allows the system to recover from transient overcurrent conditions while maintaining protection against sustained faults that would cause excessive temperature rise.
Solution Approach 2:
The patent employs feedback through the error flag output circuit that continuously monitors and reports the operational state to external devices. The feedback mechanism provides real-time information about overcurrent detection and retry operation status, enabling external systems to respond appropriately. This feedback loop ensures that the automatic recovery process is transparent and controllable, allowing external devices to take additional actions if temperature concerns arise.
3Temperature
If overheat protection function is used to cut off current at 150°C, then device is protected from excessive heat, but momentary short circuit cannot be distinguished from continuous short circuit
Solution Approach 1:
The patent applies preliminary action by detecting overcurrent conditions before they cause excessive temperature rise. The overcurrent detection circuit identifies abnormal current flow early in the fault condition, triggering protection mechanisms before the junction temperature reaches dangerous levels. This preliminary detection and response prevents the need for high-temperature cutoff, enabling distinction between transient and sustained faults based on the duration and characteristics of the overcurrent event.
Data Source
AI summary
A semiconductor integrated circuit device includes the following. An output transistor is connected between a voltage input terminal and a voltage output terminal. A control circuit controls an on state or an off state of the output transistor. An overcurrent detection circuit is capable of detecting a current that is a predetermined value or more flowing in the output transistor. A retry circuit generates and outputs a signal to intermittently switch the output transistor to the off state according to the overcurrent detection circuit detecting an overcurrent state. An external terminal outputs an error flag signal showing an abnormality. The control circuit repeats control to temporarily turn off the output transistor. After the overcurrent detection circuit detects the overcurrent state, the retry circuit is configured so that the error flag signal continuously shows an abnormality while the control circuit repeats control to temporarily turn off the output transistor.