Depopulated Pin Voltage Control in Cardiac Pacing Circuitry
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Solution Overview
Problem
Implantable medical devices face challenges in managing unused pins for cardiac pacing therapy, as these pins can be in an electrically floating state, leading to electrical noise and requiring external components that increase cost and reduce reliability.
Innovation Solution
The use of internal switches within the IC chip to selectively couple unused pins to set voltage levels, ensuring they are not used for therapy delivery and masking the connection to ground, thereby preventing false positives and ensuring a valid therapy path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If external components are used to couple unused pins to set voltage levels, then electrical noise is reduced, but device complexity and cost increase
Solution Approach 1:
The patent extracts the voltage coupling function from external components and relocates it to internal switches within the IC chip. This eliminates the need for external resistors or capacitors while maintaining the electrical noise reduction benefit, directly resolving the contradiction between noise reduction and device complexity
Solution Approach 2:
The patent merges the pin voltage control function with the existing internal switch matrix of the IC chip. By combining these functions internally, the design eliminates separate external components while achieving the same electrical noise reduction effect, thereby reducing device complexity without sacrificing noise protection
2Reliability
If external components are used to manage unused pins, then voltage control is achieved, but reliability decreases due to more connection points
Solution Approach 1:
The patent removes external components from the signal path and extracts the voltage control function entirely within the IC chip. This eliminates additional connection points and external solder joints that could fail, directly improving reliability while maintaining voltage control functionality
Solution Approach 2:
The IC chip provides self-service by internally managing the voltage levels of unused pins through integrated switches. This self-contained approach eliminates dependence on external components and their connections, thereby improving system reliability without requiring additional external parts
3Device complexity
If internal switches are used to couple pins to set voltage levels, then device complexity is reduced, but circuit board real estate is consumed
Solution Approach 1:
The patent merges multiple functions (pin voltage control, switch matrix, and depopulation logic) into a single integrated IC chip. This consolidation eliminates the need for separate external components and their associated circuit board footprint, achieving both reduced device complexity and efficient use of circuit board real estate
Data Source
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AI summary
Examples are described for configuring cardiac pacing circuitry of an implantable medical device. Circuitry that is configurable to control delivery of therapy or sense signals in accordance with a plurality of vectors may determine that one or more pins, for therapy delivery or sensing in accordance with a first subset of vectors of the plurality of vectors, are in an electrically floating state. Circuitry may selectively close one or more switches to couple at least a subset of the one or more pins to one or more set voltage levels, and deliver therapy in accordance with a vector of a second subset of vectors of the plurality of vectors, wherein the second subset of vectors is different than the first subset of vectors.