Electronic Fuse Clamp Circuit for Fast Short-Circuit Detection
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Solution Overview
Problem
Existing electronic fuses face challenges in quickly responding to short-circuit conditions while maintaining accuracy and minimizing over-current periods, which can lead to excessive heating and damage, and require complex, large, and power-consuming solutions.
Innovation Solution
The introduction of a clamp circuit that detects and responds to short-circuit conditions faster than traditional current control loops by sensing voltage differences, reducing the over-current period through a diode-connected transistor and current mirror configuration, and generating a clamp signal to control the power transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional current control loops are used to detect short-circuit conditions, then the system can maintain stability under normal conditions, but the response time to short-circuit conditions is too slow, leading to excessive over-current periods and power dissipation
Solution Approach 1:
The detection function is segmented into two independent paths: a fast clamp circuit path that detects short-circuit conditions through voltage differences and immediately generates clamp signals, and a traditional current control loop path that handles normal operating conditions. This segmentation allows the fast path to respond to short-circuits without waiting for the slower current control loop, thereby reducing the over-current period and associated power dissipation.
Solution Approach 2:
The clamp circuit performs preliminary detection of short-circuit conditions by monitoring voltage differences before the traditional current control loop can respond. By detecting the voltage drop across the power transistor during a short-circuit and generating clamp signals in advance, the system prevents excessive current flow and reduces energy loss during the critical initial phase of the fault condition.
2Speed
If complex detection circuits are implemented to improve response speed, then the response time to short-circuit conditions decreases, but the device complexity and power consumption increase
Solution Approach 1:
The clamp circuit acts as an intermediary detection mechanism that simplifies the overall system architecture. Instead of making the traditional current control loop more complex to achieve faster response, the patent introduces a dedicated clamp circuit with simple voltage difference detection that specifically handles short-circuit conditions. This intermediary path provides fast response without complicating the existing current control loop, maintaining device simplicity while improving speed.
3Reliability
If the sense transistor is always coupled to the input, then the system can continuously monitor current, but the power consumption and circuit complexity increase unnecessarily during normal operation
Solution Approach 1:
The coupling between the sense transistor and the input is made dynamic rather than static. The diode-connected transistor enables the sense transistor to be selectively coupled to the input only when short-circuit conditions are detected (when voltage difference exceeds the diode turn-on threshold). During normal operation, the sense transistor remains decoupled, minimizing power consumption. This dynamic coupling maintains reliability by enabling continuous monitoring capability when needed while reducing power consumption during normal operation.
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
The clamp circuit achieves a significantly shorter over-current period, reducing power dissipation and back electromotive force, thereby protecting the system from damage and improving response speed without increasing complexity or power consumption.
Implementation Method 1
a diode-connected transistor coupled between the input of the electronic fuse and in series with the sense transistor, the diode-connected transistor configured to conduct while the short-circuit condition exists so that the sense transistor conducts a sensed current corresponding to a current conducted by the power transistor
Implementation Method 2
a trigger circuit configured to generate the clamp signal based on the sensed current
Data Source
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AI summary
An electronic fuse that includes a clamp circuit to enhance the protection provided by the electronic fuse. The clamp circuit can detect a short circuit condition quickly and transmit a trigger signal to a controller so that a power transistor of the electronic fuse can be turned-OFF before the current through the power transistor causes overheating or damage. The clamp circuit is a dedicated circuit for short-circuit detection that can work with other current control circuits of the electronic fuse. The clamp circuit does not increase the power consumed by the electronic fuse while not in the short circuit condition. The clamp circuit is small and fast because it can use low-voltage devices, even as high voltages are present at the input and output of the electronic fuse.