June Birth Magoncia

user Electronics Engineer

city Innovuze Solutions, Inc.

  • Low Cost 5V/1A Wireless Power Transmitter

  • Created: Jan 21, 2016

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The basic concept of transmitting power wirelessly is just a transformer that has an open core consisting of transmitter and receiver coils. The wireless power controller, analog front end, and transmitter coil are soldered into a PCB or the charger pad itself, while the receiver coil and its controller are already fixed into devices, such as smartphones. When a receiver coil is placed on the transmitter coil, magnetic coupling happens. The flux is coupled into the receiver coil, which induces a voltage and current flows. The secondary voltage is rectified, and power can be delivered effectively to a load, wirelessly.

This low cost 5V/1A wireless power transmitter is based on the BQ500511 controller. The BQ500511 is paired with the BQ50002 device to provide an efficient 5W wireless power transmitter. When power is applied to the transmitter, it automatically starts to sense a receiver. The BQ500511 sends a ping to detect if there is a receiver positioned on the charger pad. If a receiver is detected, the transmitter powers the receiver and attempts to establish communication to start transferring power. The BQ500511 controls the full-bridge power stage inside the BQ50002 device that drives the transmitter coil. It also commands the BQ50002 device of how much power will be transmitted. Safety features such as foreign object detection (FOD) is also supported by the whole system. It continuously monitors the efficiency of the established power transfer to protect power lost due to metal objects misplaced in the wireless power transfer field. If any abnormal condition develop during power transfer, the BQ500511 handles the condition and provides indication outputs. Comprehensive status and fault monitoring features enable a low cost yet robust Qi-certified wireless power system design.

This reference design can be used in WPC compliant wireless chargers for smartphones or wearables. It can be also used in automotive, industrial, and medical applications. The benefit of wireless or inductive charging is that, it is more convenient since cables are not needed. Also, there is less wear and tear on the socket of the device since the there is no need to constantly plug and unplug the device. One of the disadvantages is that, it takes longer time to charge due to efficiency issues.