A charging energy control system includes an implantable medical device (IMD) and an external charger for effectuating wireless power transfer. The IMD receives charging energy to recharge a battery during an ON period and rejects the charging energy during an OFF period. A series switch is disposed between the IMD’s coil and rectifier circuitry that is controlled by voltage regulation circuitry operative to generate a clamp control signal configured to detune the coil in the OFF state.