The ICODE SLIX-S is the replacement for the ICODE SLI-S from NXP Semiconductors, within the SLIX generation, for applications requiring more memory and security: supply chain, pharmaceutical traceability, counterfeit protection, asset and document tracking. Compliant with the ISO/IEC 15693 standard (known as vicinity) and compatible with the NFC Forum Type 5 format, it offers 160 bytes of user memory that can be protected by passwords, with privacy and destroy modes. It can be read and written by the vast majority of recent NFC smartphones.
Information
| Manufacturer | NXP Semiconductors |
| Family | ICODE (SLIX generation) |
| References | SL2S5302 and SL2S5402 |
| Standard | ISO/IEC 15693 (vicinity cards) |
| NFC Forum type | Type 5 Tag compatible |
| Operating frequency | 13.56 MHz |
| Data rate | Up to 53 kbit/s |
| Unique identifier (UID) | 8 bytes (64 bits), factory programmed |
| Operating distance | Up to 1.5 m with a long-range reader; a few centimeters with a smartphone |
| Data retention | 50 years |
| Write endurance | 100,000 cycles |
| Total memory (EEPROM) | 256 bytes (2,048 bits) |
| User memory | 160 bytes |
Memory
The EEPROM memory of the ICODE SLIX-S is organized into 64 blocks of 4 bytes, grouped into pages of 4 blocks (16 bytes) for password protection; only the 40 user blocks can be addressed with the read and write commands:
| Area | Content | Access |
|---|---|---|
| Configuration area | 64-bit UID, passwords, locks, AFI, EAS and DSFID | No direct access; managed through dedicated commands |
| Blocks 0 to 39 (pages 0 to 9) | User memory (160 bytes) | Read / write, lockable block by block, protectable page by page |
In practice, the 160 bytes of user memory can hold an NDEF record containing a URL of around 145 characters, once the Capability Container (written into the first block during formatting) and the NDEF envelope are taken into account, with the common prefix (https://www. for example) compressed into a single byte. Password protection applies per 16-byte page, allowing public and restricted areas to coexist on the same chip.
Features & security
- Five 32-bit passwords: five independent passwords (read, write, privacy, destroy and EAS/AFI) individually lockable, control the sensitive functions of the chip; the read and write passwords can be combined into a 64-bit protection, which is enabled irreversibly.
- Page-level protection: each 16-byte page can be public, write-protected or read and write protected, a granularity that allows areas with differentiated access.
- Privacy mode: the Enable Privacy command silences the chip (it only responds to the Get Random Number and Set Password commands) until the privacy password is presented, in order to protect the holder's privacy.
- Destroy command: password protected, it disables the chip permanently and irreversibly; it will never respond to any command again.
- Protected EAS and AFI: the EAS anti-theft feature (with its identifier for selective alarm) and the AFI filtering are covered by the EAS/AFI password, a protection extended to the AFI that did not exist on the SLI-S.
- Locking and inventory: irreversible block-by-block locking (AFI, DSFID and EAS can also be locked) and multi-tag inventory with page reading during anticollision.
Unlike cryptographic authentication, the security of the ICODE SLIX-S relies on passwords. The chip drops the EPC command set of the SLI-S, comes in two antenna tuning versions, SL2S5302 (23.5 pF) and SL2S5402 (97 pF) for small labels, and raises data retention to 50 years.
Compatibility
The ICODE SLIX-S uses NFC-V technology (ISO/IEC 15693), 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 the chip via NFC Tools on iOS 15.6 or later, by starting the scan manually from the app.
With NFC Tools, the ICODE SLIX-S chip supports reading technical information, writing records, erasing and permanent locking. Configuring the passwords and page protections is done through the chip's dedicated commands. The list of compatible models is available in the article on compatibility.
ICODE SLI-S vs ICODE SLIX-S
| Chip | User memory | Security | Typical use |
|---|---|---|---|
| ICODE SLI-S | 160 bytes | Five passwords, privacy, destroy, EPC memory | First secured generation, existing systems |
| ICODE SLIX-S | 160 bytes | Five passwords, privacy, destroy, protected AFI | The replacement in the SLIX generation |
Both chips share the same memory, the same ISO/IEC 15693 command set and the same password arsenal. The SLIX-S extends password protection to the AFI and raises data retention to 50 years compared with 10 years, but drops the EPC command set of the SLI-S: it is the choice for any new deployment. For more memory, a counter and an originality signature, the ICODE SLIX2 takes over.
Frequently asked questions
How much data can be stored on an ICODE SLIX-S?
The chip has 160 bytes of user memory, which corresponds to a URL of around 145 characters once the Capability Container and the NDEF envelope are taken into account. Password protection can be applied page by page, in 16-byte blocks.
What is the difference between ICODE SLI-S and ICODE SLIX-S?
The memory and the ISO commands are identical. The SLIX-S extends password protection to the AFI, raises data retention to 50 years compared with 10 years, and drops the EPC command set of the SLI-S.
Is the ICODE SLIX-S 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 ICODE SLIX-S be protected against rewriting?
Yes, in two ways: a permanent, irreversible block-by-block lock, including from NFC Tools, or write protection by password, applied page by page and reversible by the password holder.
Useful links
