Protective Circuit for Digital Output Modules
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Solution Overview
Problem
The high cost of smart high side switches used in standard short circuit detection and protection solutions for digital output modules makes it economically unfeasible to implement them in digital output modules with multiple channels, as they are expensive and increase the total cost significantly.
Innovation Solution
A cost-effective protective circuit for digital output modules is developed, utilizing a first sampling unit, a comparing unit, a control unit, and a current regulating unit with transistors and voltage comparators to regulate output current and provide both overflowing and short circuit protection, allowing for each channel to have a protective circuit without excessive cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If smart high side switches are used for short circuit detection and protection in each channel, then protection reliability is improved, but total cost increases significantly
Solution Approach 1:
The patent divides the protection function into separate modular units for each channel, where each channel has its own protective circuit consisting of sampling resistors, comparators, and control transistors. This segmentation allows independent protection per channel without requiring expensive integrated smart switches for each channel, thereby reducing overall cost while maintaining protection reliability.
Solution Approach 2:
The patent uses simple, inexpensive components (resistors, comparators, transistors) that can be easily copied and replicated for each channel, replacing the need for expensive smart high side switches. These basic electronic components are widely available and cost-effective, allowing multiple channels to be equipped with protection circuits without significantly increasing total cost.
2Reliability
If protective circuits are added to each channel of digital output module, then protection coverage is improved, but device complexity increases
Solution Approach 1:
The protective circuit design uses universal, standard electronic components (comparators, transistors, resistors) that perform multiple functions: overcurrent detection, short circuit detection, and protection activation. This multi-functionality approach provides comprehensive protection coverage without requiring separate specialized components for each protection function, thereby limiting complexity increase.
Solution Approach 2:
The patent implements feedback mechanisms where sampling resistors continuously monitor current, comparators compare sampled voltages against reference thresholds, and control transistors automatically adjust or disconnect output based on detected conditions. This feedback-based automatic protection reduces the need for complex external control logic and enhances protection coverage through self-regulating circuits.
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 solution provides reliable current limiting and short circuit protection for each channel of the digital output module at a lower cost than traditional smart high side switches, making it economically viable for modules with multiple channels while maintaining protection against overcurrent and short circuits.
Implementation Method 1
a first sampling unit for sampling a first voltage relevant to the output current from the first voltage source
Implementation Method 2
a first comparing unit for comparing the sampled value with a first reference voltage
Implementation Method 3
The first transistor is configured to be conductive under low level on the base junction which is lower than a cut-off voltage
Data Source
Figure 1
Figure 2
AI summary
Embodiments of the present disclosure provide a protective circuit to be used in a digital output module, the digital output module comprises a first voltage source (SI) and at least an output terminal. The protective circuit comprises: a first sampling unit (1) for sampling a first voltage relevant to the output current from the first voltage source (SI), a first comparing unit (2) for comparing the sampled first voltage with a first reference voltage (Vrefl), a control unit (3) for generating a current regulating signal based on a result from the first comparing unit (2), and a current regulating unit (4) for regulating the output current from the first voltage source (SI) based on the current regulating signal. This protective circuit provides overflowing and short circuit protection, and is cheap in cost.