GB1287750A - Improved power supply for implantable electromedical apparatus - Google Patents

Abstract

1287750 Standby supply systems; inverting MEDTRONIC Inc 22 Oct 1969 [28 Oct 1968] 51833/69 Headings H2F and H2H A power supply in an implantable electromedical device comprises two parallel sources connected by an asymmetric conducting element so that, when the output voltage of one source falls appreciably below that of the other, only the second source continues to supply the device. The output may be connected through a voltage doubling circuit. In the arrangement shown, the power supply 10 comprises two equivalent batteries 21, 22 with their positive terminals connected to a common output line 26 through respective diodes 23, 24. Initially, both batteries will supply the device 11, which may be a cardiac pacemaker, but if one battery should fail or drop in voltage relative to the other, the corresponding series diode 23 or 24 will be back-biassed and the total power will be provided by the other battery. In a modification, Fig. 3 (not shown), a further diode is connected in series with diode 23 so that initially the battery 22 forms the main current supply. In the system shown, the device 11 emits signals on lines 52, 53 to control an output voltage doubling circuit 12 which receives power directly on line 26 (B + ) and is connected by terminals 31, 32 to the body in which the system is placed. A first signal ensures that all the transistors 51, 46, 43, 38 in the circuit 12 are off, and a capacitor 35 then charges through resistors 37 and 42 and through the body by way of terminals 31, 32. Next, a signal is supplied to turn on all the transistors, and the capacitor 35 now charges in the reverse direction through transistors 43 and 38 and again through the body. The charging cycle is normally repeated as determined by the device 11.