Multi-Stage Opto-Isolator Circuit for High Creepage Isolation
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Solution Overview
Problem
High voltage medical devices face challenges in achieving the required creepage insulation distances due to limitations in existing opto-isolators, which cannot meet the electrical safety standards for IEC 60601-1, especially at higher voltages where increased creepage distances are necessary.
Innovation Solution
The implementation of an electrical circuit design that includes a ground circuit optically coupled to a floating circuit, and the floating circuit optically coupled to an isolated circuit, using multiple opto-isolators to achieve a total creepage isolation distance that is at least twice or three times the distance provided by a single opto-isolator, effectively doubling or tripling the isolation distance from approximately 7 mm to 14 mm or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single opto-isolator is used for electrical isolation, then the device complexity is low, but the creepage isolation distance is insufficient (only up to 7 mm) to meet high voltage medical device requirements
Solution Approach 1:
The patent divides the isolation barrier into multiple segments by introducing intermediate floating circuits between the ground circuit and the isolated circuit. Each segment provides a portion of the total creepage isolation distance, and the segments are connected through opto-isolators. This segmentation allows the total isolation distance to be the sum of individual segment distances, thereby achieving greater total isolation (14 mm or more) while using standard opto-isolators that individually provide only 7 mm isolation.
2Reliability
If the creepage isolation distance is increased to meet IEC 60601-1 standards for high voltage devices, then the electrical safety is improved, but the space required on the printed circuit board increases
Solution Approach 1:
The patent utilizes the vertical dimension and layered routing on the PCB to achieve extended creepage isolation distances without proportionally increasing the horizontal footprint. By routing signals through multiple layers and using intermediate floating circuits positioned strategically, the design achieves 14 mm or more of creepage isolation while maintaining compact PCB layout. The multi-layer PCB structure allows creepage paths to extend through vertical spacing between layers rather than requiring equivalent horizontal distance.
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
This design effectively doubles or triples the creepage isolation distance, meeting the stringent requirements of IEC 60601-1 for high voltage medical devices by using multiple opto-isolators and floating circuits, ensuring safe electrical isolation while maintaining signal transmission efficiency.
Implementation Method 1
opto-isolators are electronic devices configured to transfer electrical signals via light waves (e.g., from a light-emitting diode (LED) to a photosensor (such as a phototransistor or photoresistor))
Data Source
AI summary
An electrical circuit with large creepage isolation distances is provided. In some embodiments, the electrical circuit is capable of increasing creepage isolation distances by many multiples over traditional electrical circuits. In one embodiment, an electrical circuit comprises a ground circuit optically coupled to a floating circuit, and an isolated circuit optically coupled to the floating circuit. The circuits can be optically coupled with opto-isolators, for example. The isolated circuit can have a creepage isolation distance at least twice as large as a traditional circuit. In some embodiments, “n” number of floating circuits can be optically coupled between the ground circuit and the isolated circuit to increase the total creepage isolation distance by a factor of “n”. Methods of use are also described.