STMicroelectronics ST25R3920 Automotive NFC Reader

STMicroelectronics ST25R3920 Automotive NFC Reader is an AEC-Q100 qualified Near Field Communication IC, specifically designed for CCC (Car Connectivity Consortium) digital key applications. The ST25R3920 supports NFC Initiator, Target, Reader, and Card emulation modes, and adheres to CCC Digital Key Release 2.0. This device satisfies the requirements for car access/start applications in areas like a door handle or center console, and enables additional functionality, like pairing or NFC card protection combined with a Qi wireless charger.

As the ST25R3920 features Dynamic Power Output (DPO) and Noise-Suppression Receiver (NSR) technologies, the 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. NSR technology 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 the load on the battery when the key is not being used.

Special stream and transparent modes of the AFE and framing system can be used to implement other custom protocols in the reader or card emulation modes.

The ST25R3920 from STMicroelectronics features high RF power with dynamic power output to drive antennas at high efficiency directly, achieving large interaction distance even with small antenna sizes common in door handles. The device includes additional features, making it incomparable for low power applications. It offers low power card detection by measuring the amplitude or phase of the antenna signal while reducing power consumption to a minimum. Additionally, it contains a low power capacitive sensor to detect the presence of a card without switching on the reader field.

The ST25R3920 Automotive NFC Reader is offered in a compact 5mm x 5mm VFQFPN32 package, ideal for space-constrained applications.

Features

AEC-Q100 grade 2 qualified
Operating modes
- Reader/writer
- Card emulation
- Active and passive peer to peer
Key features
- Dynamic Power Output (DPO) controls the field strength to stay within given limits
- Active Wave Shaping (AWS) reduces over-and under-shoots
- Noise Suppression Receiver (NSR) allows reception in a noisy environment
- Automatic Antenna Tuning (AAT) via variable capacitor
- Integrated EMVCo 3.0 compliant EMD handling
- Automatic gain control and squelch feature to maximize SNR
- Low power capacitive and inductive card detection
- Low power NFC active and passive target modes
- Adjustable ASK modulation depth, from 5% to 40%
- Integrated regulators to boost system PSRR
- AM/PM and I/Q demodulator with baseband channel summation or automatic channel selection
- Possibility to drive two independent single-ended antennas
- Measurement of antenna voltage amplitude and phase, RSSI, on-chip supply, and regulated voltages

RF communication
- EMVCo™ 3.0 analog and digital compliant
- NFC-A / ISO14443A up to 848kbit/s
- NFC-B / ISO14443B up to 848kbit/s
- NFC-F / FeliCa™ up to 424kbit/s
- NFC-V / ISO15693 up to 53kb/s
- NFC-A / ISO14443A and NFC-F / FeliCa™ card emulation
- Low-level modes to implement MIFARE Classic® compliant or other custom protocols
External communication interfaces
- Serial peripheral interface (SPI) up to 5Mbit/s
- I²C with up to 400kbit/s in Fast-mode, 1Mbit/s in Fast-mode Plus, and 3.4Mbit/s in High-speed mode
Electrical characteristics
- Wide supply voltage and ambient temperature range
  - 6V to 5.5V from -40°C to +105°C
  - 4V to 5.5V from -20°C to +105°C
- Wide peripheral communication supply range, from 1.65V to 5.5V
- Quartz oscillator capable of operating with 27.12MHz crystal with fast start-up
Physical characteristics
- -40°C to +105°C ambient operating temperature range
- VFQFPN32 package (5mm x 5mm)

Applications

The ST25R3920 device is suitable for a wide range of NFC and HF RFID applications, including
- CCC digital key NFC reader in locations like door handles, B-pillars, or center consoles
- NFC Forum compliant universal device for pairing applications
- Qi charging protection and NFC-based charging for in-car chargers
- EMVCo 3.0 compliant contactless payment terminal
- Original equipment, consumable and short-range location detection inside a car
- ISO14443 and ISO15693 compliant general purpose NFC device
- FeliCa™ reader / writer
- Applications requiring support for all five NFC Forum Tag types in reader mode
- Applications requiring support for all common proprietary protocols, such as Kovio, and CTS