Microprocessor controlled class E driver

1. A charger comprising:

a power source;

a class E driver forming a resonant circuit having at least one resonant frequency, the class E driver comprising:

a charging coil, wherein the charging coil is configured to magnetically couple with an implantable device to recharge the implantable device;

a switch, wherein the switch is switched by application of a first voltage to the switch, the switch comprising: a first node coupled to both the power source and the charging coil, and a second node;

a voltage sensor configured to sense a sense voltage across the switch between the first and second nodes; and

a current sensor positioned to sense a current passing through the charging coil; and

a processor electrically connected to the class E driver and configured to receive data indicative of the sense voltage across the switch and data indicative of the current passing through the charging coil,

wherein the processor is configured to control the switch via the application of the first voltage to the switch based on an identified current zero-crossing transition, and

wherein the processor is configured to receive voltage data indicative of sense voltage across the switch; and

wherein the processor is configured to modify control of the switch based on the received voltage data indicative of the sense voltage across the switch.

2. The charger of claim 1 , wherein modifying control of the switch based on the received voltage data indicative of the sense voltage across the switch comprises identifying a switching frequency of the switch and modifying the switching frequency based on the received voltage data.

3. The charger of claim 2 , wherein the switch comprises a transistor.

4. The charger of claim 3 , wherein the transistor comprises a MOSFET.

5. The charger of claim 2 , wherein the first voltage is applied to a gate of the switch.

6. The charger of claim 2 , wherein the voltage data comprises: a first sense voltage indicative of the sense voltage across the switch before closing the switch; and a second sense voltage indicative of the sense voltage across the switch after closing the switch.

7. The charger of claim 6 , wherein the first sense voltage is measured immediately before closing of the switch, and wherein the second sense voltage is measured immediately after closing of the switch.

8. The charger of claim 7 , wherein the processor is configured to control the switch in response to the second sense voltage.

9. The charger of claim 7 , wherein the processor is electrically connected to the class E driver at the first node of the switch via a voltage divider comprising a first resistor and a second resistor.

10. The charger of claim 1 , wherein modifying control of the switch based on the received voltage data indicative of the sense voltage across the switch comprises:

identifying a switching frequency with which the first voltage is applied to the switch; and

determining whether to adjust the switching frequency based on the received voltage data, wherein the adjustment of the switching frequency mitigates one or several propagation delays.

11. The charger of claim 10 , wherein modifying control of the switch based on the received voltage data indicative of the sense voltage across the switch comprises: retrieving a stored value identifying a second frequency with which the first voltage is applied based on the received voltage data.

12. The charger of claim 11 , wherein modifying control of the switch based on the received voltage data indicative of the sense voltage across the switch comprises: comparing the retrieved stored value identifying the second frequency to at least one frequency limit.

13. The charger of claim 12 , wherein modifying control of the switch based on the received voltage data indicative of the sense voltage across the switch comprises: setting the switching frequency to the second frequency when the second frequency does not exceed the at least one frequency limit.

14. The charger of claim 12 , wherein modifying control of the switch based on the received voltage data indicative of the sense voltage across the switch comprises: determining that at least one frequency limit is exceeded and setting the switching frequency to the exceeded at least one frequency limit.

15. The charger of claim 1 , wherein the first voltage is applied to the switch according to a drive signal, wherein modifying control of the switch based on the received voltage data indicative of the sense voltage across the switch comprises:

identifying an initial frequency of the drive signal;

identifying a time of a current zero-crossing transition;

sensing a voltage at the switch at the time of the current zero-crossing transition;

retrieving a value identifying a second frequency based on the voltage at the switch at the time of the current zero-crossing transition; and

changing the frequency of the drive signal.

16. The charger of claim 15 , wherein changing the frequency of the drive signal comprises changing the frequency of the drive signal from the initial frequency to the second frequency.

17. The charger of claim 15 , wherein changing the frequency of the drive signal:

retrieving a frequency limit providing at least one of: an upper bound drive signal frequencies; and a lower bound of drive signal frequencies;

comparing the second frequency to the frequency limit; and

setting the frequency of the drive signal to the frequency limit when the second frequency exceeds the frequency limit.