How does NXP's new ICODE 3 vs ICODE SLIX and ICODE SLIX 2 ?

NXP have launched the next generation of their ICODE NFC chip series - the ICODE 3. This article reviews the differences and the benefits of using the new ICODE chip compared with the previous ICODE SLIX and ICODE SLIX 2 variants. 

What is the ICODE chip ?

Back in 2006 during the early days of the NFC Forum - the industry body that regulates the standards by which NFC items communicate - there were four 'types'. The most common types are Type 2 chips, such as the widely used standard NTAG series (e.g., NTAG213, NTAG215), and Type 4 chips, including models like the authentication grade NTAG424 and DESFire chips.

A number of years later in 2015, the NFC Forum added the Type 5 standard which includes NXP's ICODE range. 

This is very important in our story here. The ICODE chip and Type 5 chips in general are good chips - at least as good, if not better in most applications compared with the standard NTAG chips such as the NTAG213. But the NTAG came first and for most mobile phone based users, became the 'industry standard'. 

Type 5 and ICODE performance - the basics

There's a number of technical differences between these chips including the communication standard. Type 2 and Type 4 chips use ISO14443 where Type 5 chips use ISO15693. Simply, this allows Type 5 tags to - in theory - have a much longer read range. In fact, in some cases, where Type 2/4 chips are called 'Near Field', Type 5 chips are referred to as 'Vicinity' chips, in reference to their longer potential range. 

In reality, without a large NFC tag and a large and powerful reader antenna array, the differences are usually minimal. Using a mobile phone as a reading device, the differences can be millimeters. 

However, ICODE and Type 5 tags do generally scan better than Type 2 tags and this difference is certainly more pronounced in smaller antenna sizes, for example, below 20mm. 

Additionally, Type 5 chips usually have a much longer memory retention specification. Type 2 chips, such as the NTAG213, have a 10 year lifespan where the ICODE, for example, has 50 year memory lifespan. 

ICODE 3 vs ICODE SLIX 2 / ICODE SLIX

There's actually a number of ICODE variants including the ICODE 3, ICODE 3 TagTamper, ICODE DNA, ICODE SLIX 2, ICODE SLIX, ICODE SLIX-S and ICODE SLIX-L. All of these have slight variations in the specification but here we will just look at the updates to the new ICODE 3 compared to the ICODE SLIX 2 and ICODE SLIX. 

Core Features

Features explained

On the face of it, the differences between the ICODE 3 and ICODE SLIX 2 are minimal. In reality, for the majority of our users, the differences aren't going to be relevant. All three variants of the chip have the same lifespan and standards. For most use cases - the storage of a URL - all three have enough memory. 

The enhanced security features may appeal to large-scale ticketing or asset management applications, but they are unlikely to be relevant for most of our customers.

NXP are advertising a faster read speed on the ICODE 3 of 212 kbit/s vs 53 kbit/s on the older chips. Again, while possibly relevant to larger scale, multi-tag reading scenarios, for the majority of our customers this isn't likely to make any noticeable difference. With a mobile phone scan, a theoretical speed increase in data transfer of a long URL could be less than five thousandths of a second. 

What the stats don't show

However, in real terms, we've always preferred the ICODE SLIX 2 to the ICODE SLIX. On our testing across a range of identical tags, the ICODE SLIX 2 shows a good 20% increase in scan performance of the ICODE SLIX. We've not tested production ICODE 3 in comparable antenna yet but another boost in scan performance would clearly be a good thing. 

Automatic SELFAdjust Mechanism Explained

One feature that is new to the ICODE 3 is NXP's SELFAdjust - and we consider this to be something special. To understand the benefit of this, let's have a quick look at how NFC tags - and specifically antennas - are made. 

Each NFC tag contains three core parts - the NFC chip, the antenna and then something to hold it together. The antenna in an NFC tag is a loop of wire which acts as an inductor, allowing the reader to generate an electro-magnetic field and therefore current. In an NFC label, this is usually a flat 'etched' antenna coil. For disc tags, PVC cards and similar items, it's usually a coil of wire. 

For an NFC tag to work effectively, this coil of wire needs to be tuned to a specific frequency which is close to 13.56 Mhz (although this does vary a little for technical reasons). In reality, this isn't easy. Even on high quality production lines, within a batch of antennas, the frequency can wander around a little. This can mean that some NFC tags don't perform quite as well as others and also don't perform quite as well as expected. 

NXP's SELFAdjust mechanism is designed to counteract this. The chip 'self tunes' itself to small variations in the antenna frequency to make sure that all the NFC tags in a batch perform with consistency. 

This technology is clearly important for any NFC tag application but becomes critical when tags are used at the edge of their scan distance performance.

Is the ICODE 3 worth it ?

At the time of writing (November 2024), we are seeing a price premium on the ICODE 3 over the ICODE SLIX 2 of around 5% at production runs of 100k. That's not a huge difference but it's still 5% for features and performance you may not need. In time, we'd expect this difference to narrow as more chips become available and more of our production runs move from ICODE SLIX 2 to ICODE 3. 

So, should you use it ? 

At the moment, we always recommend ICODE SLIX 2 against ICODE SLIX. If you aren't buying the tags from Seritag, then this is very important as the ICODE SLIX chip has little protection against lower quality clone chip copies.

If you are operating at the limit of performance, want the latest technology or can see benefit in some of the newer secrurity features then the ICODE 3 is certainly a great chip. However, for the majority of customers today, we'd still say the ICODE SLIX 2 is an excellent option until the pricing gap disappears.