Implantable cardiac stimulating device with optimized demand

A method for charging a storage capacitor in a cardiac pacing device and then discharging the storage capacitor to effect a pace, the process comprising:

• a) during a filling phase, at least two charge transfer capacitors and a combination of switches inside said capacitor bank are configured to charge the charge transfer capacitors from the battery;
• b) during a dump phase, the switch configuration is used to move charge from the transfer capacitors to a pacing supply output capacitor (28);
• c) with a) and b) continuing until the pacing supply output capacitor is charged to a desired pace output voltage (Vset) as determined by a Vset voltage comparator;
• d) the operating frequency of the charge transfer capacitor switches is varied over the useful life of the battery in order to control impedance presented to the battery terminals so that the battery pacing load current is approximately the average pacing supply charge required to replenish the pacing supply output capacitor divided by the cardiac cycle.

A method for extending battery life in a cardiac pacing device that includes a pacing supply capacitor connected to a switching power supply and that is adapted to provide a series of pacing pulses from the pacing supply capacitor, the method comprising:

• selecting a pacing supply operating frequency for the switching power supply to reduce a current required to recharge the pacing supply capacitor before a subsequent pacing pulse in the series of pacing pulses;
• monitoring battery charge depletion that results in increasing charge times for the pacing supply capacitor;
• and
• increasing the pacing supply operating frequency to compensate for the increasing charge times of the pacing supply capacitor.

A method for extending battery life in a cardiac pacing device that includes a pacing supply capacitor connected to a switching power supply and that is adapted to provide a series of pacing pulses from the pacing supply capacitor, the method comprising:

• setting a pacing supply operating frequency setting for the switching power supply to a first rate that is greater than a setting in which a charge time for the pacing supply capacitor is greater than a cardiac cycle interval;
• setting a voltage multiplier setting for the switching power supply to a reduced setting that is greater than Vpace/Vstop;
• and
• reducing the pacing supply operating frequency setting to a reduced setting that is greater than the setting in which the charge time for the pacing supply capacitor is greater than the cardiac cycle interval.

A cardiac stimulating device, comprising:

• a power terminal for a battery;
• a pacing supply capacitor;
• and
• a switching power supply connected to the power terminal and the pacing supply capacitor, and adapted for receiving current from the battery and charging the pacing supply capacitor, the switching power supply including:
• at least two capacitors having a fill configuration for receiving charge from the battery and a dump configuration for transferring charge to the pacing supply capacitor;
• and
• a frequency input for controlling a switching frequency between the fill configuration and the dump configuration such that the switching frequency is capable of being adjusted to extend battery life.

A cardiac stimulating device, comprising:

• a power terminal for a battery;
• a pacing supply capacitor;
• a switching power supply connected to the power terminal and the pacing supply capacitor, and adapted for receiving current from the battery and charging the pacing supply capacitor, the switching power supply including at least two capacitors with a fill configuration for receiving charge from the battery and a dump configuration for transferring charge to the pacing supply capacitor;
• and
• frequency controlling circuitry for controlling a switching frequency between the fill configuration and the dump configuration such that the switching frequency is capable of being adjusted to extend battery life, the frequency controlling circuitry being adapted to:
• control impedance presented to the battery terminal by adjusting the switching frequency so as to provide a relatively uniform current that is approximately an average charge required to replenish the pacing supply capacitor divided by a cardiac cycle;
• read a feature that indicates a battery strength;
• and
• alter the switching frequency based on the feature.