Introduction

The Wireless Power Consortium (WPC) is the worldwide organization that is responsible for standardizing Qi wireless charging. This includes stand-alone transmitters and receivers as well as those built into end products for consumer, industrial and automotive markets. The WPC provides the specifications for transmitters and receivers but also develops compliance tests and, through use of compliance labs, certifies that products adhere to the rigorous Qi requirements. The WPC also continues to monitor products released into the field to make sure that compliance to the standard is maintained.

The initial 1.0 and 1.1 versions of the standard allowed charging only up to a power level of 5W, which has since been referred to as the Baseline Power Profile (BPP). In 2015, the WPC introduced the Qi 1.2 15W Extended Power Profile (EPP) without authentication. Without authentication, receivers may accept a 15W charge from non-certified designed chargers that can cause damage to the receiving device. That is why the WPC released the Qi 1.3 standard in 2021, requiring one-way hardware-based authentication to verify that the charger was tested and approved by the WPC and their accredited test labs. When a receiver, such as a cell phone, is placed on a Qi 1.3 power transmitter, it will initially accept a 5W charge, then, after a successful X.509-based ECC asymmetric authentication proving the charger is an approved "do no harm" device, the phone will safely accept a > 5W charge and up to a maximum of 15W, depending on the phone capability. To ensure a high level of security and reliability, the WPC has created a Root Certificate Authority (CA) and requires a Secure Storage Subsystem (SSS) that meets the requirements defined by the WPC to be built into all transmitters that intend to support the Qi 1.3 EPP. All Qi-certified authenticated transmitters must have their manufacturing CAs signed by the WPC Root CA.

Microchip Technology Inc. is a long-time member of the WPC and, as a company, is involved in developing reference designs for its customers’ power transmitters and receivers. Microchip is also a major player in the security world, providing secure devices and provisioning services. Having this level of background, Microchip was an active participant on the WPC Committees that created the Qi authentication specification and is now supporting the market with multiple hardware products and services.

The TA100 is a hardware SSS that meets the Qi authentication requirements for automotive transmitters. The remainder of this document provides the necessary information on WPC requirements and describes how Microchip’s secure provisioning capabilities and the TA100 can be used to meet those requirements.