Use PKE And NFC To Unlock The Automotive Market

NFC

NFC is a short-range wireless technology that facilitates the secure exchange of data. It is being increasingly adopted for secure transactions, including use by mobile phone manufacturers to create an “electronic wallet.” NFC combined with an embedded secure element offers consumers a high level of convenience, interactivity, and security with their mobile devices. It operates at 13.56 MHz at rates ranging from 106 to 424 kbits/s, so NFC-enabled smart phones could be used for RKE functions.

3. NFC-enabled RKE systems potentially could enable smart phones with NFC to be used for car access functions.

NFC communication involves an initiator and a target. To transmit data between two NFC interfaces, one NFC interface activates its transmitter and works as an NFC initiator. The high-frequency current that flows in the antenna induces a magnetic field that spreads around the antenna loop and moves through the antenna loop of the other NFC interface located close by. A voltage is then induced in the antenna loop of the other NFC interface, which detects the voltage with its receiver. 

If the NFC interface receives signals and the corresponding commands of an NFC initiator, this NFC interface automatically adopts the role of an NFC target. For data transmission between the NFC interfaces, the amplitude of the emitted alternating field is modulated (amplitude shift keying, or ASK, modulation). The transmission direction is reversed to send data from the NFC target to the NFC initiator. If an NFC interface is located close to a compatible RFID reader, the NFC interface adopts the role of an NFC target and can transmit data to the reader using load modulation. This mode is called “card emulation mode.”

An NFC interface also can communicate with compatible passive transponders. The interface can supply these transponders with power, and these transponders can transmit data back to the NFC interface via load modulation. In this case, the NFC interface adopts the role of a radio-frequency identification (RFID) reader.

NFC can be used for car access if a reader is installed in a way that it is accessible from outside the car (e.g., located in the side mirror). This is particularly helpful in communities that share cars or other situations where different people have access to a number of cars (e.g., company car fleets).

ICs are available for RKE, PKE, and NFC applications. For example, the Melexis MLX90132 was designed and qualified for automotive systems, making it robust and durable in retail, consumer, and industrial NFC applications (Fig. 4). This 13.56-MHz, fully integrated, multi-protocol RFID/NFC transceiver IC supports ISO/IEC protocols 18092, 14443A and B, 15693, and 18000-3.

4. The Melexis MLX90132 NFC transceiver includes the 125-kHz RFID transceiver and the 13.56-MHz NFC transceiver.

The MLX90132 handles subcarrier frequencies from 106 to 848 kHz and baud rates up to 848 kbits/s. Its digital section handles the low protocol layers from the application programming interface (API) to the physical layer (PHY) using advanced bit and frame decoding functions. The IC embeds tag emulation functionality for NFC support. Enhanced tag and field detection capabilities significantly reduce power consumption in RFID reader configuration and in NFC mode.