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Wireless charger system circuit module and solution



Wireless charger system circuit module and solution


How a user interacts with a device is one of the most basic questions that every good engineer has to ask when the project starts. Do customers need to charge quickly? Need alignment flexibility? Does it require low heat? Need to charge long distances? Need high power? Each transmitter requires multiple receivers? Need a small form factor? All of these options are satisfactory, but they often need to be traded off. For example, high power and low calorific value are not always satisfied at the same time. Distance and efficiency are basically the opposite. Therefore, it is an important first step to understand what the user needs and how to prioritize these requirements when designing a wireless charging system for a device.


In the indicators used to measure the performance of wireless charging systems, efficiency is always first. Naturally efficient systems can provide longer distances, better directional flexibility, lower heat generation, smaller size, and smaller power leakage currents. The following are the three major modules that have a decisive impact on efficiency in wireless charging systems:


Wireless charging system circuit module and solution detailed


Three modules of wireless charging system


If all three modules work at the lowest estimated efficiency (ie, 80%, 70%, and 80% as shown in the figure), then the total system efficiency is approximately equal to 45%. For a 5W device, 11W of transmit power is required to provide full-speed charging, and approximately 6W is dissipated in the device itself (as heat is dissipated) and in the surrounding environment, including air, devices, and human tissue. In low power situations, this may be safe and acceptable. However, when the power is higher, such as the charging of an electric vehicle, the typical charging power at this time is at least 5 kW, then there are 6 kW to be lost in the transmitter, the car and the surrounding environment, which may cause serious heat and safety problems. When all three modules of the wireless charging system operate at the highest estimated efficiency (ie, 95%, 90%, and 95%), the total system efficiency is approximately 82%. In this case, a 5W device requires only the transmitter to provide about 6W of charging power, and only 1W is lost due to invalidation. To increase system efficiency, designers should focus on high-efficiency components to increase the degree of coupling between transmitters and receivers.


Panasonic Wireless Charging Reference Design


Panasonic Wireless Power Control IC supports all devices (DSC, DVC, Walkman, mobile phones, smart phones, etc.) and conforms to WPC (Qi standard) of WPC (Wireless Charging Alliance). The Panasonic Wireless Power Solution uses a transmitter control IC (NN32251A ($5.0312)) for a power transmitter (battery charger) and a receiver control IC (AN32258A) for a power receiver (device) to control Power transmission.


Wireless charging system circuit module and solution detailed


NN32251A Development Kit (Tx)


Wireless charging system circuit module and solution detailed


Image of Launch Module for NN32251A Development Kit


AN32258A Development Kit (Rx)


Wireless charging system circuit module and solution detailed


AN32258A Development Kit Receiver Module Image


 


 


Supports wireless charging based on various WPC1.1 (Qi standard) devices. Anomaly detection and various protection functions during the charging process ensure safety and reliability. Supports a maximum 5W output within the standard range for fast charging. Provides efficient control of external low-impedance MOSFETs to reduce power consumption and heat generation. (AN32258) Provides solutions including Panasonic coils and peripheral circuits to achieve short theoretical time-of-arrival (TAT) designs.