Improved power circuitry for charging a battery in an implantable medical device is disclosed. The improved power circuitry uses a DC-DC converter positioned between the rectifier and the battery in the implant to be charged, and operates to boost the voltage produced by the rectifier to a higher compliance voltage used to charge the battery. Because the rectifier can now produce a smaller DC voltage, the AC voltage preceding the rectifier (the coil voltage), can also be lessened. Lowering the coil voltage reduces the amount of heat generated by the coil, which reduces the overall heat generated by the implant during receipt of a magnetic charging field from an external charger during a charging session, which improves patient safety. Additionally, a reduced coil voltage means that the external charger can reduce the intensity of the magnetic charging field, which also reduces heat generated in the external charger during the charging session.
