Electronic Fuse Circuit with Mode-Based Current Reduction
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Solution Overview
Problem
Existing electronic circuit breakers, or e-fuses, lack adequate fault tolerance and functional safety, particularly in automotive applications, where standards like ISO 26262 must be met, and they often consume excessive current.
Innovation Solution
A circuit and method for an electronic fuse that includes an electronic switch with a control circuit generating a drive signal based on an input signal and a monitoring circuit determining a protection signal from the load current and wire parameters to decide whether to disconnect the output node from the supply node, featuring a normal mode and an idle mode to reduce current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If common driver circuits are used in electronic circuit breakers, then the circuit can be simple and easy to manufacture, but fault tolerance and functional safety are inadequate
Solution Approach 1:
The driver circuit is divided into two distinct operational modes: normal mode for standard switching operations and restricted mode for fault conditions. This segmentation allows the circuit to have simple default operation while incorporating enhanced safety mechanisms that are activated only when needed, thus improving reliability without permanently increasing complexity
Solution Approach 2:
The circuit dynamically transitions between normal mode and restricted mode based on detected fault conditions. The operational characteristics of the driver circuit are adjusted in real-time according to the system state, allowing the circuit to adapt its complexity and safety measures only when necessary, thereby maintaining simplicity during normal operation while ensuring safety when faults occur
2Reliability
If the monitoring circuit operates continuously in normal mode, then functional safety is maintained, but current consumption is excessive
Solution Approach 1:
The monitoring circuit operates periodically rather than continuously, switching between active monitoring in normal mode and inactive state in restricted mode. This periodic operation maintains functional safety when needed while significantly reducing current consumption during periods when fault conditions are not present, directly resolving the contradiction between safety and energy use
Solution Approach 2:
The operational parameters of the monitoring circuit are changed based on system state: in normal mode, the circuit operates with full monitoring functionality and appropriate current consumption; in restricted mode, the monitoring is reduced or suspended to minimize current draw. This dynamic parameter adjustment allows the circuit to optimize the trade-off between safety and energy consumption based on real-time conditions
Data Source
AI summary
An electronic fuse circuit includes an electronic switch with a load current path coupled between an output node and a supply node and that connects or disconnects the output node and the supply node in accordance with a drive signal. The circuit includes a control circuit to generate the drive signal based on an input signal. A monitoring circuit is included in the control circuit to receive a current sense signal representing the load current passing through the load current path and to determine a first protection signal based on the current sense signal and a wire parameter. The first protection signal is indicative of whether to disconnect the output node from supply node. The control circuit changes from normal mode to idle mode when the load current is below a given current threshold and another criterion is fulfilled.