At the recent Telecommunication Certification Body Council Workshop in Baltimore, Kwok Chan and Mark Neumann of the Federal Communications Commission (FCC) Office of Engineering and Technology outlined testing and certification requirements for Consumer Wireless Charging Devices.
Wireless charging devices are generally used to charge batteries in portable electronic devices via magnetic induction. Chargers can deliver up to 5W of power, enough to charge most wireless handsets, and work at distances up to 10mm.
These products have been around since the 1990s, but only have become practical in recent years, so FCC thought it was worthwhile to cover how these devices fall into the existing regulatory compliance framework. Following are main points from the presentation.
Chargers and clients are generally approved separately; however, they should satisfy compliance in both standalone mode and as a system.
Wireless charging devices can be approved under Part 15 or Part 18 or both rule parts.
Part 15 authorization required if:
- Primary charging frequency includes information not related to power management
- A secondary frequency is used for communications
Part 18 authorization for the charger and clients:
- Load and power management must be integral to wireless charging operation and frequency
- May not communicate any information not related to power management and control
- Proximity of the charger and client device(s) must satisfy Part 18 requirement that the RF energy is locally generated and used
- Other communications are authorized separately under Part 15
Electromagnetic Compatibility (EMC) considerations:
- Charger must be evaluated with appropriate client(s) in place
- The worst case transmitting conditions for the system as a whole must be evaluated for each applicable configuration: Bluetooth, WWan, WLan, etc.
Radio Frequency Exposure
Single client low power devices generally do not present exposure concerns for nearby users, but multi-client devices or short-distance power transfer can result in widely varied fields and potential exposure concerns.
For most small consumer chargers, exposure conditions identified in §2.1091(d)(4) may apply.
Specific Absorption Rate (SAR) and Maximum Permissible Exposure (MPE) limits do not cover wireless chargers operating below 100 kHz and 300 kHz, respectively.
The presentation concluded with two points:
- A KDB Inquiry should be submitted for guidance for wireless charger applications
- Wireless Chargers remain on the Permit But Ask (PBA) list
Sign up for a Wireless Testing & Certification Seminar in Austin, Texas in December.