HF / NFC Recommendation 
NTAG 213 / 215 / 216
For NFC applications with smartphones and NDEF content.
Security PWD
Memory 144–888 B
ICODE® SLIX: Technical Data, Security and Use
The ICODE SLIX from NXP is a passive HF RFID chip for 13.56 MHz. It operates according to ISO/IEC 15693 and ISO/IEC 18000-3 and is designed for applications with a greater read distance. The chip has 1,024 bits of EEPROM, of which 896 bits or 112 bytes are directly accessible user memory. Typical applications are libraries, media labeling, industrial labeling and asset tracking.
Today, ICODE SLIX is mainly of interest for existing applications. NXP labels the product as “Not Recommended for New Designs” and names ICODE SLIX2 or ICODE 3 as successors, depending on the capacitance variant of the chip. For new projects, it should therefore be checked whether the newer ICODE generations are a better fit.
| Feature | Value |
|---|---|
| Manufacturer | NXP Semiconductors |
| Product family | ICODE |
| Type designation | SL2S2002 / SL2S2102 |
| RFID class | HF / NFC |
| Frequency | 13.56 MHz |
| Standard | ISO/IEC 15693, ISO/IEC 18000-3 Mode 1 |
| NFC standard | NFC-V / NFC Forum Type 5 Tag |
| Data rate | Up to 53 kbit/s |
| EEPROM / total memory | 1,024 bits / 128 bytes |
| User Memory | 896 bits / 112 bytes |
| Memory structure | 32 blocks of 4 bytes each; 28 of which are directly accessible user memory blocks |
| Authentication | 32-bit password for EAS/AFI; no cryptographic authentication of the user memory |
| Encryption | None |
| UID | 64 bits, factory-programmed and unchangeable |
| Anti-collision | Yes, true anti-collision; additionally Fast Inventory Read |
| EAS | Yes, optionally protected with a 32-bit password |
| AFI | Yes, optionally protected with a 32-bit password |
| Block lock | Each user memory block can be individually locked against further writing |
| Read range | Up to 1.5 m gate width according to NXP, depending on antenna geometry and reader system |
| Write cycles | 100,000 |
| Data retention | 50 years |
| Smartphone NFC | Yes, via ISO/IEC 15693 / NFC-V with suitable devices and apps |
| Product status at NXP | Not recommended for new designs |
| Typical media | RFID label, sticker, library label, card and special transponders |
| Security rating | Basic |
| Recommendation | Mainly for existing ISO 15693 applications; consider current ICODE generations for new projects |
ICODE SLIX operates at 13.56 MHz and, according to NXP, achieves an operating distance of up to 1.5 m gate width with suitable antenna geometry. The maximum data rate is 53 kbit/s. The EEPROM comprises 128 bytes, of which 112 bytes are directly readable and writable as user memory. The remaining memory areas contain internal configuration data such as UID, access information, passwords, AFI and EAS.
Typical Applications
ICODE SLIX was developed for smart labels and applications in which several transponders in the read field are to be detected or a greater read distance than with classic proximity chips is required. NXP names the following areas of use in particular:
- Libraries
- Labeling of individual items in pharmaceutical supply chains
- Product authentication and labeling of consumer goods
- industrial applications
- Asset tracking
- Document tracking
In practice, ICODE SLIX is mainly used for libraries, media labeling and article surveillance. RFID labels, stickers and other flat transponder forms are particularly suitable for this. Depending on the application, cards or special transponders are also possible.
Suitable media: RFID stickers, industrial RFID labels, NFC tags and RFID cards.
Security
Security level: Basic
ICODE SLIX has no cryptographic authentication of the user memory. The 28 directly accessible user memory blocks can be individually and permanently locked against further writing. The 64-bit UID is programmed during production and cannot be changed afterwards.
A 32-bit password is provided for the EAS and AFI functions. With the original ICODE SLIX, however, it does not generally protect read or write access to the user memory. NXP also describes locking mechanisms for DSFID, AFI and EAS.
This is sufficient for labeling, library and inventory applications that require block-level tamper protection and EAS functions. For applications with cryptographic authentication or greater protection against copying and manipulation, other chips are required. Newer ICODE generations offer significantly more extensive functions. ICODE SLIX2 adds password protection for read and write access, privacy mode, a destroy function and an originality signature, among other things.
Advantages and Disadvantages of ICODE SLIX
| Advantages | Disadvantages |
|---|---|
| Up to 1.5 m gate width with suitable antenna geometry | No longer recommended by NXP for new designs |
| ISO/IEC 15693 for library, inventory and labeling applications | Only 112 bytes of directly usable user memory |
| True anti-collision for multiple tags in the read field | No cryptographic authentication or encryption of the user memory |
| EAS and AFI with optional 32-bit password protection | 32-bit password protects only EAS/AFI, not the user memory in general |
| User memory blocks can be individually and permanently locked against writing | Newer ICODE generations offer more memory and additional security and privacy functions |
Alternatives to ICODE SLIX
Depending on the application, desired smartphone use, security requirements and required read range, other chip types may be better suited.
HF / NFC Recommendation 
MIFARE DESFire EV3
For applications with higher security needs and AES-128.
Security AES-128
Memory 2 / 4 / 8 / 16 KB
HF Legacy 
MIFARE Classic 4K
For existing HF systems with higher memory requirements. Only partially readable by smartphone.
Security Broken
Memory 4 KB
Frequently Asked Questions about ICODE SLIX
How much memory does ICODE SLIX have?
ICODE SLIX has a total of 1,024 bits or 128 bytes of EEPROM. Of this, 896 bits or 112 bytes are directly accessible as user memory. This area consists of 28 blocks of four bytes each. The remaining EEPROM area is used internally for configuration data such as UID, write protection, access information, password, AFI and EAS and cannot be addressed like normal user memory.
Which variants of ICODE SLIX are available?
The data sheet describes the types SL2S2002 and SL2S2102. The main difference lies in the input capacitance between the antenna connections: SL2S2002 operates with typically 23.5 pF, SL2S2102 with typically 97 pF. Both variants use the same basic memory and protocol architecture. The different capacitance is relevant for the design of the transponder and its antenna.
How secure is ICODE SLIX?
ICODE SLIX offers an unchangeable 64-bit UID, permanently lockable user memory blocks and locking functions for DSFID, AFI and EAS. A 32-bit password can protect EAS and AFI. However, the original ICODE SLIX does not offer cryptographic authentication or encryption of the normal user memory. The password protection should therefore not be equated with the security mechanisms of modern chips with AES authentication.
Can ICODE SLIX be read with a smartphone?
In principle, yes, provided the smartphone, operating system and application support ISO/IEC 15693 or NFC-V. With NfcV, Android provides an interface for ISO 15693 tags; this technology is one of the mandatory tag technologies for Android NFC devices. Apple Core NFC also supports ISO 15693 tags via its own interface. Which data an app actually processes depends on the implementation and the configuration of the tag.
Which readers support ICODE SLIX?
A reader that supports 13.56 MHz and ISO/IEC 15693 is required. For ICODE-specific functions such as EAS, Fast Inventory Read or password commands, the reader must also be able to process the corresponding commands. The specification “13.56 MHz” alone is therefore not sufficient for a compatibility guarantee. For existing library, inventory or labeling systems, the reader model and the functions used should be checked before reordering.
What is the read range of ICODE SLIX?
NXP specifies an operating distance of up to 1.5 meters, depending on the antenna geometry. This figure should be understood as a possible gate width under suitable system conditions and not as a guaranteed read range of every label. Reader power, reader antenna, transponder antenna, installation situation and environment influence the distance actually achievable. ICODE SLIX is thus one of the ISO 15693 vicinity chips for applications that require greater distances than typical proximity cards.
What is the difference between ICODE SLIX and ICODE SLIX2?
ICODE SLIX2 is the newer successor and, according to NXP, backward compatible with ICODE SLIX. It offers 2,560 bits of memory and significantly more security and privacy functions. These include password protection for read and write access, privacy mode, a password-protected destroy function, a 32-byte originality signature and a counter. ICODE SLIX, by contrast, has 1,024 bits of EEPROM and limits its 32-bit password protection to EAS and AFI.
Can the memory of ICODE SLIX be permanently locked?
Yes. Each user memory block has a locking mechanism for write protection. DSFID and AFI can also be locked. There is also a lock function for EAS. Such locks should only be set after encoding has been completed, because a locked memory area cannot subsequently be released for writing again in the regular way.
Is ICODE SLIX still recommended for new projects?
No. NXP currently lists ICODE SLIX with the status “Not Recommended for New Designs”. For the 23.5 pF variant, NXP names ICODE SLIX2 or ICODE 3 as an alternative. For the 97 pF variant, NXP refers to ICODE 3. Existing applications may still require ICODE SLIX, but for a new project a current ICODE generation should be considered.
Request RFID Media with ICODE SLIX
Do you need RFID labels, cards or other transponders with ICODE SLIX for an existing application?
For the technical review, the desired media format, quantity, the existing reader system, the required encoding and information on EAS, AFI and memory allocation are helpful. For new projects, it should also be checked whether ICODE SLIX2, ICODE 3 or another current chip is a better fit for the application.
Technical sources
Data as of: September 2026
The technical information is based on the NXP product data sheet SL2S2002_SL2S2102, ICODE SLIX, Rev. 3.4 dated 10 August 2017 and the current NXP product page. Among other things, the data sheet describes ISO/IEC 15693 and ISO/IEC 18000-3, 13.56 MHz, up to 53 kbit/s, 1,024 bits of EEPROM, 896 bits of user memory, the 64-bit UID, EAS/AFI password protection as well as write cycles and data retention.
For the current product classification, the NXP product pages for ICODE SLIX2 and ICODE 3 and the current ICODE product family overview were also checked. NXP labels ICODE SLIX as not recommended for new designs.
The information on smartphone support is based on the Android documentation on NFC-V and Apple's Core NFC documentation for ISO 15693 tags.
Trademark notice
ICODE is a trademark of NXP B.V.