System and method of protecting transformer-driven switches from external magnetic fields
First Claim
1. A telemetry device for use in an implantable cardiac stimulation device including a protection device that protects the stimulation device from a potentially damaging external magnetic field, the protection device comprising:
- a carrier control circuit that generates a high frequency carrier signal and that charges an energy storage device with a drive voltage;
switching elements connected to the energy storage device;
a control circuit coupled to the switching elements, that selectively inhibits the application of the drive voltage to the switching elements whenever the drive voltage falls below a predetermined threshold level, and that applies the drive voltage to the switching elements whenever a drive voltage exceeds the threshold level.
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Accused Products
Abstract
A protection device for use in an implantable medical device such as an ICD that communicates with an external programmer. The protection device includes one or more control blocks that inhibit gate triggers for the switching elements (IGBTs) of an H-bridge whenever the drive voltage for these switching elements falls below a pre-determined level. Each control block provides a controlled path to charge the IGBT gate when triggering is required and, importantly, when the gate drive voltage is above a predetermined threshold. The control block further prevents inadvertent or spurious triggering and protects the gate circuitry of the switching elements by providing a low impedance path between the gates and sources of the IGBTs when the latter switching elements are intended to be turned OFF. Additionally, the control blocks protect the IGBTs from over-voltage effects by clamping the output of the gate trigger with a shunt regulator circuit.
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Citations
23 Claims
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1. A telemetry device for use in an implantable cardiac stimulation device including a protection device that protects the stimulation device from a potentially damaging external magnetic field, the protection device comprising:
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a carrier control circuit that generates a high frequency carrier signal and that charges an energy storage device with a drive voltage;
switching elements connected to the energy storage device;
a control circuit coupled to the switching elements, that selectively inhibits the application of the drive voltage to the switching elements whenever the drive voltage falls below a predetermined threshold level, and that applies the drive voltage to the switching elements whenever a drive voltage exceeds the threshold level.
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2. A device for protecting an implantable stimulation device from a potentially damaging external magnetic field, comprising:
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means for generating a high frequency carrier signal and for charging an energy storage means with a drive voltage;
switching means; and
control means for selectively inhibiting the application of the drive voltage to the switching elements whenever the drive voltage falls below a predetermined threshold level, and for applying the drive voltage to the switching elements whenever a drive voltage exceeds the threshold level.
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3. An implantable cardiac stimulation device including a protection device that protects the stimulation device from a potentially damaging external magnetic field, the protection device comprising:
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a carrier control circuit that generates a high frequency carrier signal and that charges an energy storage device with a drive voltage;
switching elements connected to the energy storage device;
a control circuit coupled to the switching elements, that selectively inhibits the application of the drive voltage to the switching elements whenever the drive voltage falls below a predetermined threshold level, and that applies the drive voltage to the switching elements whenever a drive voltage exceeds the threshold level. - View Dependent Claims (4, 5, 6, 7)
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8. A device for protecting an implantable stimulation device from a potentially damaging external magnetic field, comprising:
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a carrier control circuit that generates a high frequency carrier signal and that charges an energy storage device with a drive voltage;
switching elements connected to the energy storage device;
a control block coupled to the switching elements, that selectively inhibits the application of the drive voltage to the switching elements whenever the drive voltage falls below a predetermined threshold level, and that applies the drive voltage to the switching elements whenever a drive voltage exceeds the threshold level. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
wherein when the carrier signal is interrupted, the quick discharge circuit causes the conductive switching element to be discharged expeditiously.
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22. The device according to claim 21, wherein the quick discharge circuit includes three transistors that are configured as a triple Darlington circuit.
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23. The device according to claim 21, wherein the quick discharge circuit provides a low impedance path across the conductive switching element during discharge, rendering the switching element untriggerable, and thus protected from inadvertent triggers and high voltage transients.
Specification