What this RFID reader brings to a contactless design
The STMicroelectronics ST25R3911-BQFT is a multi-protocol RFID/NFC reader IC operating at 13.56 MHz, designed for contactless payment terminals, access control readers, and NFC-enabled embedded systems. It supports FeliCa, ISO 14443 Type A/B, MIFARE Classic and DESFire, and NFC Forum tag types through a single SPI host interface.
Obsolete — sourcing reality for production
ST lists the ST25R3911-BQFT as obsolete. Any new design should target the ST25R3912 or a current-generation ST25R reader for long-term supply assurance.
The pad is the main thermal path — without a proper via stitch, junction temperature rises quickly under continuous field generation at high output power.
Protocol support and integration notes
The SPI interface runs at standard clock rates for register configuration and data streaming. The chip handles the full ISO 14443 framing and collision resolution in hardware, so the host MCU only needs to exchange APDU blocks. MIFARE Classic crypto is also on-chip, offloading the authentication from the host.