Power transmission control device, power transmission device, electronic instrument, and non-contact power transmission system

A non-contact power transmission system comprising a power transmission device and a power reception device, the non-contact power transmission system transmitting power from the power transmission device to the power reception device by electromagnetically coupling a primary coil and a secondary coil to transmit the power to a load of the power reception device,

• the power reception device including a power reception section that converts an induced voltage of the secondary coil into a direct-current voltage;
• the power transmission device including:
• a drive clock signal generation circuit that generates a drive clock signal that specifies a drive frequency of the primary coil;
• a driver control circuit that generates a driver control signal based on the drive clock signal, and outputs the driver control signal to a transmission driver that drives the primary coil;
• a waveform detection circuit that detects a waveform of an induced voltage signal of the primary coil;
• and
• a control circuit that detects a power-reception-side load state based on a detection result of the waveform detection circuit;
• the waveform detection circuit including a first pulse width detection circuit that measures a first pulse width period to detect first pulse width information, the first pulse width period being a period between a first edge timing of the drive clock signal and a first timing, the first timing being a timing when a first induced voltage signal that has changed from a low-potential-side power supply voltage exceeds a first threshold voltage;
• and
• the control circuit detecting the power-reception-side load state based on the first pulse width information.