The ICODE SLIX is the third generation of NXP Semiconductors' ICODE family and the direct, backward-compatible replacement of the ICODE SLI: libraries, 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 112 bytes of user memory and adds password protection for the EAS and AFI features. It can be read and written by the vast majority of recent NFC smartphones.
Information
| Manufacturer | NXP Semiconductors |
| Family | ICODE (SLIX generation) |
| References | SL2S2002 and SL2S2102 |
| 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) | 128 bytes (1,024 bits) |
| User memory | 112 bytes |
Memory
The EEPROM memory of the ICODE SLIX is organized into 32 blocks of 4 bytes, including 28 user blocks; only blocks 0 to 27 can be addressed with the read and write commands:
| Area | Content | Access |
|---|---|---|
| Configuration area | 64-bit UID, EAS/AFI password, locks, AFI, EAS and DSFID | No direct access; managed through dedicated commands |
| Blocks 0 to 27 | User memory (112 bytes) | Read / write, lockable block by block |
In practice, the 112 bytes of user memory can hold an NDEF record containing a URL of around 95 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: encoding a short redirect link is recommended. The structure is identical to that of the ICODE SLI, guaranteeing compatibility with existing systems.
Features & security
- EAS/AFI password: a 32-bit password, writable and lockable, protects the EAS and AFI features; the protection is enabled separately for each of them, irreversibly. This is the major addition compared with the ICODE SLI.
- EAS (Electronic Article Surveillance): a built-in anti-theft feature, detectable at a gate with a dedicated command, which can be enabled, disabled and locked.
- AFI (Application Family Identifier): an application family identifier filters the inventory by object type, to sort mixed logistics flows.
- Multi-tag inventory: the ISO/IEC 15693 anticollision, complemented by the inventory read and fast inventory read commands, makes it possible to census many tags simultaneously present in the field.
- Block-by-block locking: each 4-byte block can be write-protected irreversibly; the DSFID, AFI and EAS can also be locked. The operation can be performed directly from NFC Tools.
- Symmetrical range: the write distance is equal to the read distance, an asset for encoding tags on the fly on a logistics line.
The ICODE SLIX has neither read and write passwords for the memory, nor the privacy mode: those features belong to the ICODE SLIX-S and SLIX2. The chip comes in two antenna tuning versions, SL2S2002 (23.5 pF) and SL2S2102 (97 pF) for small labels.
Compatibility
The ICODE SLIX 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 chip supports reading technical information, writing records, erasing and permanent locking. The EAS/AFI password is managed through the chip's dedicated commands. The list of compatible models is available in the article on compatibility.
ICODE SLI vs ICODE SLIX
| Chip | User memory | Security | Typical use |
|---|---|---|---|
| ICODE SLI | 112 bytes | EAS and AFI without password | First generation, existing systems |
| ICODE SLIX | 112 bytes | EAS and AFI protectable by password | The backward-compatible replacement |
Both chips share the same memory and the same protocol. Beyond password protection, the SLIX raises data retention to 50 years, compared with 10 years for the SLI: it is the default choice for any new deployment. For read and write passwords, the privacy mode or more memory, the ICODE SLIX-S and SLIX2 take over.
Frequently asked questions
How much data can be stored on an ICODE SLIX?
The chip has 112 bytes of user memory, which corresponds to a URL of around 95 characters once the Capability Container and the NDEF envelope are taken into account. Encoding a short redirect link is recommended.
What is the difference between ICODE SLI and ICODE SLIX?
The memory and the protocol are identical, and the SLIX is fully backward compatible. It adds password protection for the EAS and AFI features and raises data retention to 50 years, compared with 10 years for the SLI.
Is the ICODE SLIX 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 be protected against rewriting?
A permanent, irreversible lock is possible block by block, including from NFC Tools. The SLIX password only protects the EAS and AFI features, not memory writing: for password-based write protection, the ICODE SLIX-S or SLIX2 are the chips to consider.
Useful links
