Next-generation NFC reader IC for digital car keys

STMicroelectronics has extended its portfolio of ST25R NFC reader ICs with the ST25R3920. The device introduces enhanced features for stronger performance, including rapid key response and extended range.

Digital keys let drivers lock and unlock their cars using their smartphones, and support added-value features including easy sharing and management of access privileges for other users such as friends or valets.

Together with unique Dynamic Power Output (DPO) and Noise-Suppression Receiver (NSR) technologies, the new device increases RF output power and offers an enhanced input-circuit design for rapid car-key response and superior user convenience.

With DPO, the device operates at up to 1.6W continuous RF output power and 2.5W short-term input peak, to maintain reliable NFC connections over distance with a small antenna. ST’s NSR increases immunity to interference from noise sources and therefore simplifies electromagnetic immunity and eases certification. In addition, automatic antenna tuning compensates for changes in the RF environment to maintain the best possible connection to the user’s smartphone, and low-power key-signal detection with inductive wakeup minimizes load on the battery when the key is not being used.

Designed for space-constrained locations that severely limit the maximum antenna size, the ST25R3920 can be positioned in door handles, B-pillar, or the centre console.

The ST25R3920 supports the CCC Digital Key Standardization Release 2.0, the architecture endorsed by the world’s leading carmakers, smartphone manufacturers, and electronics suppliers. A CCC member, ST plays a key role in setting NFC standards as a member of the NFC Forum board, various working groups, and ISO 14443 and ISO 15693 task forces.

The chip is certified by NFC Forum and can work as an NFC reader or NFC universal device. Compliance with NFC Forum standards for pairing applications, as well as EMVCo 3.0 standards, allows use as an in-car contactless-payment terminal for services such as electric-vehicle charging. In addition, a new and unique Qi wireless charging NFC-card protection algorithm enables safe wireless charging of portable devices.