Transformer Charging Circuit for Implantable Medical Devices
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Solution Overview
Problem
The miniaturization of implantable medical devices (IMDs) is hindered by the need for complex circuitry that increases component count and power consumption, which complicates the goal of advancing technological capability while maintaining device longevity.
Innovation Solution
A charging circuit utilizing a single primary transformer winding and a single secondary winding coupled to multiple capacitors, with a diode to maintain charging polarity, and a coupling circuit that dynamically configures capacitors in various stacking configurations to reduce power consumption and footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If complex circuitry is used to advance technological capability, then device functionality is improved, but component count and power consumption increase
Solution Approach 1:
Multiple capacitor charging functions are merged into a single transformer winding configuration. The patent uses one primary winding and one secondary winding to charge multiple capacitors (C1, C2, C3) that are connected in parallel, eliminating the need for separate windings for each capacitor and reducing overall component count while maintaining the ability to deliver complex therapy waveforms
Solution Approach 2:
The single transformer winding configuration serves multiple functions: it charges multiple capacitors simultaneously, provides the necessary voltage for therapy delivery, and enables both pacing and defibrillation/cardioversion therapies through the shared capacitor bank, making the circuit universally applicable to various therapy modes without requiring dedicated circuits for each function
2Adaptability or versatility
If complex circuitry is used to advance technological capability, then device functionality is improved, but power consumption increases
Solution Approach 1:
Multiple capacitor charging operations are merged into a single simultaneous charging event. By connecting capacitors C1, C2, and C3 in parallel and charging them together through the single secondary winding, the circuit eliminates redundant charging cycles and associated power losses, reducing overall power consumption while maintaining the capability to deliver complex multi-phase therapy waveforms
Solution Approach 2:
The capacitors are pre-charged to the required voltage level before therapy delivery. The circuit charges all necessary capacitors in advance during a dedicated charging phase, ensuring that when therapy is delivered, the energy is already stored and ready for immediate release, minimizing the need for additional power consumption during the actual therapy delivery phase
3Speed
If supply voltage is increased to charge capacitors, then charging speed is improved, but component stress and power consumption increase
Solution Approach 1:
The capacitors are connected in parallel configuration, creating equipotential charging conditions where all capacitors are charged to the same voltage level simultaneously. This approach allows efficient charging at moderate voltage levels without the need for excessive supply voltage, reducing component stress while maintaining acceptable charging speed through the combined capacitance effect
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 solution reduces the supply voltage required for charging, decreases the component count, and enhances the reliability of IMDs by efficiently charging capacitors and optimizing therapy delivery waveforms, thereby extending device longevity and improving therapeutic efficacy.
Implementation Method 1
a charging circuit (40) that charges a plurality of output capacitors (62) to a predetermined voltage level
Implementation Method 2
A diode is coupled between the secondary transformer winding and the plurality of capacitors to maintain a predetermined charging polarity
Implementation Method 3
The plurality of capacitors may be charged up to a predetermined voltage level subsequent to being coupled in the parallel configuration by the coupling circuit
Data Source
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AI summary
Recent advancements in electronics technology have provided opportunities for enhancements to implantable medical devices. The enhancements have contributed to increasing miniaturization and operation efficiency. The techniques of the disclosure facilitate configuring a stimulation therapy waveform based on a patient's physiological response to the stimulation waveform. The generated therapy stimulation waveforms include a stepped leading-edge that may be shaped having a varying slope and varying amplitudes associated with each of the segments of the slope. Unlike the truncated exponential waveform delivered by the conventional therapy delivery circuit which is based on the behavior of the output capacitors (i.e., i=C(dV/dt)), the stimulation waveform of the present disclosure may be dynamically shaped as a function of an individual patient's response. The dynamically shaped therapy stimulation waveforms facilitate achieving lower capture thresholds which reduces the device's supply consumption and reduction of tissue damage.