Battery life extender
US4237897A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 3, 1978 |
| Grant date | Dec 9, 1980 |
| Priority date | — |
| Expiry date | Nov 3, 1998 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61N1/378
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A battery life extender for use in an implantable tissue stimulator. The tissue stimulator comprises a battery which powers a volatile memory, control circuits and a pulse output circuit all of which are connected in parallel across the battery. The invention provides a means for controlling current through the output circuit as a function of a difference voltage between the battery output voltage and a reference voltage. The reference voltage and battery voltage comprise inputs to a differential amplifier which in turn provides an output control voltage which controls a field-effect transistor (FET) connected in series with the output circuit and battery. As this control voltage rises, current through the field-effect transistor is reduced, thereby reducing the amplitude of the pulses from the output circuit and the current drain from the battery. This keeps the battery output voltage high and maintains a more nearly constant voltage on the volatile memory and control circuits for a longer period of time than would otherwise be available.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.