Multi-Sense Circuit for Parallel Power Switch Overcurrent Protection
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Solution Overview
Problem
When multiple power switches are connected in parallel, existing solutions face challenges in effectively evaluating and protecting against overcurrent conditions due to limited available pins, leading to either incomplete evaluation or incorrect measurement of maximum current, which can result in damage to power switches.
Innovation Solution
A multi-sense circuit that includes a peak detector and control subcircuit, utilizing a diode array and sense resistors to detect the highest current across parallel-connected power switches, allowing for overcurrent protection by generating a signal to shut down the most heavily loaded switch, even with limited pins available.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple power switches are connected in parallel to handle higher current, then the current carrying capacity is improved, but the complexity of detecting and protecting against overcurrent conditions increases due to limited available pins
Solution Approach 1:
The patent combines multiple sense resistors (one for each parallel power switch) into a single integrated sensing network. The sense nodes are connected through diodes to a common detection circuit, merging multiple individual sensing paths into one unified detection mechanism that identifies the maximum current across all parallel switches using minimal external pins.
Solution Approach 2:
The detection circuit performs multiple functions: it monitors current in each parallel power switch individually, identifies the maximum current across all switches, and triggers protection when any switch exceeds safe operating conditions. This multi-functional approach eliminates the need for separate detection circuits for each switch, reducing pin requirements while maintaining comprehensive protection.
2Measurement precision
If traditional sensing circuits are used for each parallel power switch, then individual overcurrent detection is achieved, but the number of required pins and circuit complexity increases
Solution Approach 1:
Multiple sense resistors are connected in parallel configurations with their sense nodes tied together through diodes. This merging allows individual current sensing for each power switch while sharing common detection infrastructure, reducing the total number of pins required compared to independent sensing circuits for each switch.
Solution Approach 2:
The patent uses identical sense resistors and diode structures for each parallel power switch, creating replicated sensing units. This copying approach ensures consistent detection accuracy across all switches while using standardized components that can be integrated efficiently, reducing overall circuit complexity.
3Device complexity
If a single sense resistor is used for parallel power switches, then pin count is reduced, but accurate identification of the most heavily loaded switch becomes difficult
Solution Approach 1:
Each parallel power switch has its own dedicated sense resistor and sense node, providing localized current measurement for that specific switch. This local sensing ensures accurate identification of the most heavily loaded switch, while the diode network efficiently routes these local measurements to a central detection point, maintaining both precision and low pin count.
Solution Approach 2:
The sensing circuit is segmented into individual sense branches for each power switch, with each branch containing its own sense resistor. These segmented branches are then combined through diodes to a common detection node, allowing the circuit to maintain individual measurement capability while using a unified detection mechanism that requires minimal pins.
4Reliability
If overcurrent protection is implemented for parallel power switches, then switch safety is improved, but the circuit response time and complexity increase
Solution Approach 1:
Sense resistors are pre-installed in each power switch circuit path, and sense nodes are pre-configured with diode connections to the detection circuit. This preliminary setup ensures that when overcurrent occurs, the detection circuit can immediately identify the faulty switch without requiring complex real-time analysis, reducing protection response time while maintaining reliable protection.
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 multi-sense circuit effectively identifies and addresses overcurrent conditions in parallel-connected power switches, preventing damage by accurately detecting the maximum current and triggering protection measures, even with restricted pin availability, thus ensuring safe operation.
Implementation Method 1
The peak detector can comprise a plurality of diodes, each diode of the plurality of diodes having an anode respectively coupled to an input of the plurality of inputs of the peak detector and a cathode coupled to the output of the peak detector
Implementation Method 2
Each transistor of the plurality of parallel-connected transistors can further comprise a sense resistor coupled to a respective sense node of the plurality of sense nodes
Data Source
AI summary
A multi-sense circuit includes a transistor circuit having sense nodes and a gate node, a peak detector having inputs coupled to the sense nodes of the transistor circuit and an output, and a control circuit having a gate control node coupled to the gate node of the transistor circuit and an overcurrent protection node coupled to the output of the peak detector.