The ST25TN family gathers the NFC Forum Type 2 tags from STMicroelectronics, designed for very high consumer volumes: consumer engagement, product information, brand protection, smart city and access control. Compliant with levels 2 and 3 of the ISO/IEC 14443A standard and certified NFC Forum Type 2 (the format natively supported by Android and iOS), its two references offer 64 or 208 bytes of user memory, enriched with the Augmented NDEF (a dynamic message composed at each read, with a unique tap code), the TruST25 digital signature and a kill mode. They can be read and written by the vast majority of recent NFC smartphones.
Information
| Manufacturer | STMicroelectronics |
| Family | ST25TN |
| References | ST25TN512 and ST25TN01K |
| Standard | ISO/IEC 14443A (levels 2 and 3) |
| NFC Forum type | Certified Type 2 Tag |
| Operating frequency | 13.56 MHz |
| Data rate | 106 kbit/s |
| Unique identifier (UID) | 7 bytes, factory programmed |
| Tuning capacitance | 50 pF |
| Operating distance | A few centimeters depending on the antenna |
| Data retention | 40 years |
| Write endurance | 100,000 cycles |
| User memory | 64 or 208 bytes depending on the reference |
The references of the family
The ST25TN family comes in two references built on the same silicon, which share the protocol, the Augmented NDEF and the whole set of protections:
| Reference | User memory | Highlights |
|---|---|---|
| ST25TN512 | 64 bytes | The entry point, for short links and identification |
| ST25TN01K | 208 bytes | The comfortable version, for vCards and rich content |
The memory is organized as 64 blocks of 4 bytes, all permanently readable. In NDEF usage, the ST25TN512 hosts a URL of around 55 characters, and the ST25TN01K up to around 200 characters, enough for a vCard or a link enriched with parameters.
Memory
The memory of the ST25TN chips follows the classic organization of NFC Forum Type 2 tags, in 4-byte blocks spread over three areas:
| Area | Content | Access |
|---|---|---|
| System area (first blocks) | 7-byte UID, OTP area and Capability Container | Set at the factory or permanently lockable |
| User memory | 64 or 208 bytes hosting the NDEF message | Read / write, lockable block by block |
| System configuration | Augmented NDEF fields, system locks, kill mode, TruST25 key identifier | Access restrictable and lockable |
The Capability Container announces the NDEF capacity to the smartphone, and the locks (static and dynamic, compliant with the Type 2 specification) make it possible to freeze the memory block by block, permanently. The configuration drives the dynamic fields of the Augmented NDEF and the kill mode.
Features & security
- Augmented NDEF and unique tap code: the NDEF message can be automatically enriched with dynamic fields, composed at each presentation without rewriting the EEPROM, including a unique 3-digit tap code renewed at each tap (a proof of real reading that a screenshot cannot imitate) and a customizable separator.
- TruST25 digital signature: each chip embeds a unique digital signature, generated by STMicroelectronics during production, which makes it possible to verify the authenticity of the silicon and detect clones; a key identifier allows revocation.
- Permanent Type 2 compliant locks: both the user memory and the system area can be permanently write-protected, block by block, through the locking mechanism of the NFC Forum T2T specification.
- Kill mode: a configurable mode permanently deactivates the tag, to protect the holder's privacy or mark the end of the product's life.
- Native universality: certified NFC Forum Type 2 and natively supported by Android and iOS, the chips work with a simple antenna (50 pF internal tuning, power entirely harvested from the reader's field), without any additional component.
- Built for volumes: positioned on the cost and performance balance, they come as standard wafer, thinned wafer (75 µm) and DFN5 package for every label form factor.
The write protection of the ST25TN relies on its permanent locks: the family does not offer a reversible password on the user memory, a choice consistent with its economical positioning.
Compatibility
The ST25TN chips use NFC-A technology (ISO/IEC 14443A), supported by the vast majority of recent NFC smartphones. On Android, reading and writing work natively with NFC Tools, without any particular restriction. On iPhone, automatic background reading is available from the iPhone XS and XR onwards; models from the iPhone 7 can read and write these chips via NFC Tools on iOS 15.6 or later, by starting the scan manually from the app.
With NFC Tools, the ST25TN chips support reading technical information, reading and writing NDEF records, erasing and permanent locking. The kill mode and the Augmented NDEF fields are managed through the chip's dedicated commands. The list of compatible models is available in the article on compatibility.
ST25TN vs NTAG213
| Chip | User memory | Strengths | Typical use |
|---|---|---|---|
| ST25TN (512 and 01K) | 64 or 208 bytes | Augmented NDEF, unique tap code, TruST25, kill mode | Consumer engagement and brand protection |
| NTAG213 | 144 bytes | UID and counter mirrors, 32-bit password | The reference for consumer tags |
Both play on the same field of the economical, universal Type 2 tag: the ST25TN bets on authenticity (TruST25 signature, unique tap code) and the kill mode, the NTAG213 on its ecosystem and its reversible password protection, absent from the ST25TN whose locks are permanent. For more memory on the NXP side, the NTAG215 and NTAG216 take over.
Frequently asked questions
Which ST25TN reference should I choose?
The ST25TN512 (64 bytes, i.e. a URL of around 55 characters) covers short links and identification; the ST25TN01K (208 bytes, around 200 characters) hosts vCards, links enriched with parameters and richer content.
What is the Augmented NDEF?
An NDEF message composed dynamically at each read, without rewriting the memory: the chip can insert contextual fields into it, including a unique 3-digit tap code renewed at each presentation. A server can thus distinguish a real read from a simple copy of the link, an asset for consumer engagement and fraud fighting.
Are the ST25TN chips compatible with iPhones?
Yes. Background reading works from the iPhone XS and XR onwards, and both reading and writing are possible via NFC Tools from the iPhone 7 on iOS 15.6 or later.
Can an ST25TN chip be protected against rewriting?
Yes: permanent, irreversible locking applies block by block, in accordance with the Type 2 specification, including from NFC Tools. The family does not offer a reversible password: for that feature, the NTAG213 or ST25TA are the way to go.
