Qi2 adds security measures to fast wireless charging

This article originally appeared in the Nov'23 magazine issue of Electronic Specifier Design – see ES's Magazine Archives for more featured publications.

Figure 1. Qi2 uses magnetic positioning to align devices while charging, opening up applications such as wearable device charging on non-flat surfaces. (Image: Nucurrent)

The cellular/3GPP is a global standard announced at CES 2023 with more details a month later at MWC 2023. The Qi2 (pronounced “chee 2”) upgrade is intended to make wireless charging of wearable and mobile devices, such as smartphones, e-readers, and tablets, more efficient, convenient and faster than its predecessor, Qi.

Paul Struhsaker, Executive Director of the WPC believes it will clarify some confusion in the marketplace around device interoperability. “Our standard assures consumers that their devices are safe, efficient, and interoperable with other brands. Qi2 will be the global standard for wireless charging and provide consumers and retailers with that assurance,” he commented at MWC.

Magnetic attraction

A key feature of the upgraded standard is its magnetic power profile which will ensure that phones or other rechargeable battery-powered mobile devices are precisely aligned with charging points or devices. A magnetic ring aligns a device with the charger. In addition to removing imprecision in receiver and transceiver alignment, charging can be faster and more energy efficiently, with less energy loss. This allows the wireless charger to snap into the back of a smartphone, or other devices, to ensure a secure connection. The precise alignment also makes it safer and a more sustainable method because energy loss during charging is typically converted into heat which can be destructive to battery health.

“Just as important, Qi2 will greatly reduce the landfill waste associated with wired charger replacement due to plugs breaking and the stress placed on cords from daily connecting and disconnecting," adds Struhsaker.

Other designers are excited about the range of devices and applications that can integrate a Qi2 charger once they are liberated from the constraints of having to have flat surfaces matching other flat surfaces for charging. This opens up possibilities in smart speakers, casino gaming, personal grooming, point of sale, and industrial handheld devices.

There was an update on the standard at IFA 2023, the consumer and home appliance show in Berlin, Germany in September. Companies, including Anker announced Qi2 wireless chargers, power banks, and magnetic pads supporting 15W fast wireless charging. Qi2 is based on Apple’s MagSafe magnetic charging technology. Apple released its iPhone 15 series in September this year, saying it will support both MagSafe and Qi2. Accessory provider, Belkin introduced its BoostCharge Pro 3-in-1 wireless charging pad in Berlin at the beginning of September. It has two Qi2 chargers and a port for a USB-C Apple Watch charger, to charge three devices simultaneously.

Qi2 products

Qi has been widely adopted and is popular so to lessen the pain of upgrading products to the new wireless charging standard, NuCurrent and Amphenol Airwave Communication Electronics have developed a Qi2 charging module. The Qi2 Max allows OEMs to migrate Qi1 systems and achieve Qi2 certification and accelerate time to market. The Qi2 module can be customised enabling consumer, industrial and medical products to meet power levels, product size, interoperability, product lifespan and the certification requirements set by the WPC.

The module uses NXP Semiconductor’s MWCT20D2VLH silicon which is equipped security capabilities for on-chip authentication in support of the WPC’s challenge to eliminate counterfeit, non-Qi-certified devices.

Vaclav Halbich, Product Manager, NXP Semiconductors believes that authentication is one of the most important features of the Qi2 standard, “providing the safety and security features needed to protect end users.”

Qi2 also requires more testing than Qi1, with the requirement to pass stringent magnetics and foreign object detection (FOD) tests. Ensuring tight manufacturing tolerances is critical to achieving certification.

The module will be manufactured by Amphenol Airwave.

Figure 2. A Qi2 MPP charging transmitter reference kit was demonstrated by Infineon Technologies at its annual technology forum in the US

Most recently, at OktoberTech, Infineon Technologies’ annual forum, the company demonstrated a Qi2 magnetic power profile (MPP) charging transmitter reference kit. The REF_WLC_TX15W_M1 has a diameter of just 43mm and features a programmable wireless charging transmitter and Infineon’s Qi2-capable WLC1 controller. The IC integrates a microcontroller with flash memory, a 4.5 to 24V DC input buck-boost controller, inverter gate drivers and factory-trimmed current sensing, together with analogue protection peripherals, USB PD, LIN, and serial interfaces.

The 15W Qi2 reference kit is supported with code examples in ModusToolbox and is backwards compatible with a basic power profile (BPP) that allows receivers without MPP support to wirelessly charge at 5W. There is also a multi-path ASK demodulator and adaptive foreign object detection (FOD) for security protection.

Figure 3. The enhanced Qi standard, Qi2, is based on magnetic coil position for fast, efficient charging. (Image: Nucurrent)