Transmission of information from an implanted medical device

An implantable device requiring electrical power from an external power source for operation, comprising:

• an LC tank circuit that receives a power signal from the external power source;
• a rectifier that rectifies the power signal;
• a load-generating device to which the rectified power signal is delivered;
• a voltage-to-frequency converter that senses a load voltage level of the power delivered to the load-generating device and produces a pulsed feedback signal comprising a series of pulses, the frequency that the pulses are generated being indicative of tit load voltage level;
• and
• a switch that superimposes the pulsed feedback signal on the LC tank circuit for communication to the external power source.

A medical system with transcutaneous energy transfer comprising:

• an external electrical power source having a power driver and a primary LC tank circuit;
• and
• an implantable device requiring electrical power from an external power source for operation, comprising:
• a secondary LG tank circuit that receives power from the external power source;
• a load-generating device to which the received power is delivered;
• and
• feedback circuitry that senses a load voltage level of the power delivered to the load-generating device, produces a pulsed feedback signal indicative of the load voltage level, and superimposes the feedback signal on the secondary LC tank circuit for communication to the external power source, wherein during a time that the feedback signal is superimposed on the LC tank circuit receipt of power from the external power source is interrupted.

An external power source for an implantable device requiring electrical power from an external power source for operation, the external power source comprising:

• an electrical power supply;
• a pulse-width modulator and driver for generating a power signal;
• an LC tank circuit for transmitting electrical energy;
• and
• a sensor that senses a feedback signal provided by the implantable device through the LC tank circuit, the feedback signal indicative of a load voltage level and comprising a series of pulses, the frequency that the pulses are generated being indicative of the load voltage level;
• wherein the external power source varies the amount of power delivered to the implantable device in response to the feedback signal.

An implantable device requiring electrical power from an external power source for operation comprising:

• an LC tank circuit that receives power from the external power source;
• a load-generating device to which the received power is delivered;
• and
• circuitry that senses a condition, produces a signal comprising one or more pulses and which is indicative of the condition, and superimposes the signal on the LC tank circuit for communication to die external power source.

An implantable device requiring electrical power from an external power source for operation, comprising:

• an LC tank circuit that receives power from the external power source;
• a load-generating device to which the received power is delivered;
• and
• feedback circuitry that senses a load voltage level of the power delivered to the load generating device, produces a feedback signal indicative of the load voltage level, and superimposes the feedback signal on the LC rank circuit for communication to the external power source, wherein the feedback signal comprises a series of pulses and the frequency that the pulses are generated is indicative of the load voltage level.

An implantable device requiring electrical power from an external power source for operation, comprising:

• an LC tank circuit that receives power from the external power source;
• a load-generating device to which the received power is delivered;
• and
• feedback circuitry that senses a load voltage level of the power delivered to the load-generating device, produces a feedback signal indicative of the load voltage level, and superimposes the feedback signal on the LC tank circuit the communication to the external power source, wherein the feedback circuitry comprises a switch that receives the feedback signal and is coupled with the LC tank circuit so that during the time the feedback signal is pulsed high the switch closes and the LC tank circuit is short-circuited to superimpose the feedback signal on the LC tank circuit.