Multi-Channel High-Side Switch Safety I/O Module With Redundant Outputs
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Solution Overview
Problem
Existing safety I/O modules in industrial control systems require redundant switches that increase cost, printed circuit board space, and assembly complexity, making them inefficient for applications with space constraints or cost sensitivity.
Innovation Solution
A safety I/O module with a multi-channel high side switch integrated circuit and individual safety switches, where each output channel has a redundant pair of switches that connect or disconnect the voltage input terminal based on the conductive state of both switches, reducing the number of components and simplifying assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant switches are used in safety output channels, then safety reliability is improved, but device complexity and assembly complexity increase
Solution Approach 1:
Multiple main switches are integrated into a single integrated circuit chip, combining what would otherwise be separate discrete components. This merging maintains the redundant switching architecture for safety while reducing the number of individual components that need to be handled and assembled, directly addressing the contradiction between reliability and assembly complexity
2Reliability
If redundant switches are used in safety output channels, then safety reliability is improved, but the number of components increases
Solution Approach 1:
The integrated circuit combines multiple main switches into a single chip package, reducing the total component count. Instead of having separate discrete switches for each channel, the integration consolidates them, maintaining safety functionality while reducing the quantity of individual components
3Reliability
If redundant switches are used in safety output channels, then safety reliability is improved, but printed circuit board space increases
Solution Approach 1:
By integrating multiple switches into a single IC chip, the physical footprint on the printed circuit board is dramatically reduced. The chip occupies significantly less space than multiple discrete switch components would require, allowing the redundant safety architecture to be implemented in space-constrained applications
Data Source
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AI summary
A safety I/O module includes a plurality of output channels and a plurality of channel output terminals. The safety module further includes a multi-channel high side switch comprising an integrated circuit including a voltage input terminal and a plurality of main switches. A plurality of discrete safety switches are also provided. Each of the output channels includes a redundant pair of switches including one of the main switches of the multi-channel high side switch and one of the safety switches arranged in series. The main switch and the safety switch are configured to: (i) operably connect the voltage input terminal of the multi-channel high side switch to a respective one of the channel output terminals when both the main switch and the safety switch are in a conductive state; and (ii) disconnect the voltage input terminal of the multi-channel high side switch from the respective one of the channel output terminals when at least one of the main switch and the safety switch are in a non-conductive state. A method of operating a safety I/O module includes operating a plurality of main switches of a high side multi-channel switch integrated circuit to selectively conduct a supply voltage from a voltage input terminal to at least one discrete safety switch and operating the safety switch to selectively conduct the supply voltage to a respective one of the channel output terminals.