“ST’s Vision Is To Make Wireless Charging Faster Than Wired Charging”

Foo Leng Leong, senior technical marketing manager, STMicroelectronics

An increase in the number of portable electronic devices has led to the need for high-power charging options. Foo Leng Leong, senior technical marketing manager, STMicroelectronics, in a conversation with the EB team, discusses the company’s latest offering for USB-C type data transfer and charging applications.

STMicroelectronics has released a high-power receiver and transmitter that can gain up to 80 per cent efficiency. According to the company, the device is suitable for portable applications and is completely RoHS compliant.

In order to simplify the existing, highly-cluttered data transfer connectivity methods, STMicroelectronics (ST) has been involved in developing high-end products for USB-C type data transfer and charging for several years. In 2017, this was achieved with the launch of ST’s STUSB1602 and now with the introduction of the STWLC68, a high-power receiver and transmitter.

“ST has a comprehensive roadmap for wireless charging solutions spanning the full power range. We want to introduce new features for end users and, at the same time, respect the environment. The high efficiency of our innovative solutions helps us do that,” says Foo Leng Leong, senior technical marketing manager, ACP, STMicroelectronics.

The aim is to provide users with an efficient wireless charging option that has advanced safety features and can enable rapid power transfer.

Making wireless charging faster
Since its inception in 2015, USB-C type data transfer has been dominating the market due to its high power output. However, the wireless charging standards have not kept pace with this advancement.

“A key reason is the lack of a wireless receiver that is capable of delivering high power. Most wireless devices follow Qi EPP standards of 15W, which is lower than the technological limits of wireless charging,” states Leong.

Leong hopes that the situation will change soon. “ST solutions can go beyond this and we’re working with standardising groups to get these approved for the consumers’ benefit. Our target is to achieve wireless charging that is faster than wired charging,” he explains.

Minimal power losses
According to the company, for Rx (reception/receive) only, the worst case power loss with the STWLC68 is around 3 per cent to 4 per cent at high temperature conditions. However, the system losses can be higher than this due to coupling and alignment losses, as well as heat losses in the coil and capacitive tank. The operating temperature range for the device is 0° Celsius to 85° Celsius.

Leong adds, “We have developed and implemented (in compliance with the Qi 1.2.4 standard) our proprietary protocol which allows for higher power as well as authentication, handshaking and pairing.”

Suitable for applications ranging from 5W to 20W

The STWLC68 has a fully integrated, low-impedance, high-voltage synchronous rectifier and low drop-out linear regulator, for achieving high efficiency and low power dissipation. It is suitable for applications ranging from 5W to 20W.

The I2C interface allows firmware and platform parameters to be customised in the device, and the configuration can be programmed into the embedded OTP. Besides this, the wireless charging IC family is supported by an online simulation environment.

“To name just a few of the configuration parameters that can be embedded into the STWLC68 OTP, there is protection, in-band communication, proprietary protocols, current limits and GPIO functions,” says Leong.

He concludes, “We have a design suite that helps our users design and implement wireless charging efficiently and effectively. Our online GUI has such tools, including coil selection and design tools, as well as system tuning and configuration adjustments to assist in the application of our solutions.”


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