Efficient NFC transceiver enabling new application areas

23rd June 2021

Alex Lynn

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Datasheet

The ST25R3918 from STMicroelectronics is a multi-purpose NFC transceiver supporting passive peer-to-peer functionality and NFC card-emulation mode as well as NFC reader operation. It delivers most of the functionality of the flagship ST25R3916 NFC reader at a competitive price, the ST25R3918 also enables use cases such as accessory identification for a wide range of applications including power tools and personal healthcare devices where the ST25R3918 interacts with ST25 tags. Its close relationship to the ST25R3916 simplifies hardware design and certification.

Supporting NFC-A and NFC-F card emulation, the ST25R3918 can be used as an NFC-A/B (ISO 14443A/B) card reader up to high bit rates, and as an NFC-V (ISO 15693) reader up to 53 kbps, as well as ISO 18092 passive initiator and target. The card emulation mode allows support for the newest features available on mobile phones.

End customers can use their phones to interact easily with applications that utilise the ST25R3918, including using a simple tap to start apps on the phone. Device programming and simple NDEF data transfers are also permitted. In addition, users can leverage special stream and transparent modes of the analog front end (AFE) and framing system to implement other custom protocols in card-reader and card-emulation modes.

Combined with the reader mode, the ST25R3918 sports a feature set that allows scanning for tags nearby for tasks such as replaceable detection and parameter setting, or simply reading an access card. Moreover, the user can interact with the mobile phone while collecting valuable data on customer behavior and accessories used, which adds an additional stream of information for product development.

With high sensitivity and the added benefit of ST’s Noise Suppression Receiver (NSR) technology, the ST25R3918 provides an extended and reliable read range and can be operated with output power around 0.5W in noisy and harsh environments. The ST25R3918 also includes a low-power card-detection mode to scan for the presence of a card by measuring the amplitude or phase of the antenna signal. A low-power RC oscillator and wake-up timer automatically reactivates the ST25R3918 after a selected time period to check for the presence of a tag.

Additional features to maximise the performance and value from this transceiver include support for Dynamic Power Output (DPO), which automatically controls the field strength to meet the required limits. On top of this, Active Wave Shaping (AWS) smooths the waveform for better signal integrity.

The ST25R3918 operates from a wide power-supply voltage range of 2.6 to 5.5V between -40 and +85°C, and 2.4 to 5.5V in the temperature range from -20 to +85°C, with a peripheral-I/O voltage range of 1.65 to 5.5V.

The ST25R3918 is available now, priced at $1.80 in quantities of 1,000 units.