Power reception device and power transmission system

A power transmission system including:

• a power transmission device including a primary coil;
• and
• a power reception device including a secondary coil, wherein:
• the power transmission device is configured to drive the primary coil and transmit AC power corresponding to a clock signal which is frequency-modulated by a binary data signal,
• the primary coil and the secondary coil are electromagnetically coupled together to receive by the secondary coil in the power reception device, thereby the AC power is transmitted from the power transmission device to the power reception device,
• the power reception device comprises:
• a clock-signal extraction circuit configured to extract the clock signal from an induced voltage induced at one end of the secondary coil in receiving the AC power and output the extracted clock signal;
• and
• a demodulation circuit configured to generate a pulse synchronously with the extracted clock signal, and demodulate the pulse to obtain the binary data signal, and
• the clock-signal extraction circuit is applied with the induced voltage as an input, limits the induced voltage between an upper limit and a lower limit and outputs the limited induced voltage as the extracted clock signal, the induced voltage exceeding the upper limit and falling below the lower limit.