Which NFC Chip ?

What is an NFC chip ?

At the heart of every NFC tag, sticker or product is an NFC 'chip' or 'IC' (integrated circuit). These tiny electronic devices store your information, manage the communication to your phone and control how it can be accessed.

The NFC chip is connected to an antenna and held together with a substrate. All NFC tags will contain an chip, but the antenna size, design and shape can vary. If you aren't sure what a tag actually is, then read our what is an NFC tag guide. 

NFC IC types

Different NFC chips have varying amounts of memory and features. The amount of memory will determine how much data you can store on your chip. Additional features can include password protection, scan counters or tamper detection. Some NFC chips also have advanced encryption features and can be used for NFC authentication and anti-counterfeit. 

Chip availability

The price that you pay for your tags and products will be very closely related to the quantities being made. High volume manufacture reduces the pricing significantly and therefore most tag production tends to lean towards a very small selection of chips. Generally, the NTAG213 chip is the most commonly available for NFC tags being used with mobile phones. If you using a non-standard chip, then plan ahead and carefully check availability and production costs.

Genuine vs. fake

Rule No. 1 : Unless the cost of replacing the NFC tag is less than a few pence/cents and/or you don't mind some of the tags not working, then buy quality tags and genuine chips.

The vast majority of NFC chips within tags sold via retailers and large scale tag manufacturers are currently made by NXP Semiconductors. There are however, a number of non-genuine NXP chips around. In the past, this was a particular problem with the the MIFARE Ultralight but Seritag have seen an increasing number of 'clone' NTAG213 chips on the market. 

Using genuine chips is strongly recommended. The scan performance, memory reliability and long term stability are critical factors in most NFC applications and it's not worth the tiny (if any) savings in using clone chips. In fact, the reliability and quality of non-genuine chips varies between not great and truly shocking. Duplicate UID's, widely variable scan distances and in-situ or application failures are common with fake or clone chips. There aren't going to be many projects which will find the savings worthwhile.

Choosing your NFC IC

Let's keep it simple.

Use an NTAG213 chip for all normal NFC applications and the NTAG424 for authentication/anti-counterfeit applications. 

The only reasons not to use these chips is because :

You need more memory. In which case your best option is usually the NTAG215 or possibly the ICODE SLIX 2. The NTAG216 might be a bit more common but Seritag have had a few too many emails regarding the reliability in terms of encoding and/or reading large amounts of data. The NTAG215 and ICODE SLIX 2 seem to have no such problems.

Your application requires a different chip (access cards for example). In some cases, older applications might require a different chip such as the MIFARE Ultralight or even the MIFARE Classic. Note that most door entry systems will use non NFC chips. If you aren't sure, then Seritag can help you work out which chips you are currently using and give advice on whether you can switch or if we need to provide a specific chip for your application (which we usually can). 

You need tamper detection features. Both the NTAG213 and NTAG424 are available as 'Tag Tamper' (TT) versions which can register a tamper and still scan. This is different than a normal tamper tag which simply stops working on tamper. 

Memory size

Rule No. 2 : More memory doesn't give you better performance. Don't use a chip with more memory than you need.

Seritag take the view that the NFC tag should be an ID and link to data on the internet or 'in the cloud' rather than the store of data itself. In which case, the standard NTAG213  should be more than enough even for longer tracking URLs or a simple ID. You can use our NFC Tag memory calculator to check which chip you might need. We also have a quick reference guide on how much NFC tag memory you might need.

If you do need to start storing data on the tag itself, perhaps because there might not be internet access when the tags are scanned, then the larger NTAG215 or ICODE SLIX 2 chips can help.

However, be careful. Many NFC projects find even these can be restrictive and it must always be considered that all NFC tags have a very limited memory capacity. You also need to make sure that your App or system is reliable as there have been reports of timeout and other errors when storing large datasets to the larger chips, such as the NTAG216, from a mobile phone.

It's also worth bearing in mind that the larger NTAG215/216 chips and other similar variants are more expensive than the more common versions. Some other alternative chips, such as the MIFARE Classic, are not NFC Forum compatible so that also needs to be considered as they won't scan on many phones, including the iPhone. 

In summary, we strongly recommend that you should use the tag as an ID or link to internet based data. It's a far more flexible and cost-effective way to go. If you have to store longer URLs, then consider using a tag management system which can act as a URL shortener and also provide dynamic URL options (ability to change tag destination after deployment). 

Popular NFC Chips

NXP's NTAG series chips are by far the most common for mobile use. The basic details are listed here and there's a breakdown of each of these features and chips below.

Memory vs. user memory

Both Memory and User Memory are listed here in bytes. Memory is the total amount of memory within the chip. It's worth noting that relative to other memory devices such as USB sticks, etc, this is very, very small. In fact, most NFC tags can store no more than roughly a single sentence of text.

However, within that memory space there are sections which are reserved for the function of the tag. For example, information regarding permission to change the data, the UID of the chip (which can't be changed on genuine chips), and so on. This means that a user wishing to store data onto the tag can't use all the available memory space and only the space minus this important data - the 'user memory'.

**The NTAG424 is a complex authentication tag with various memory sectors. Total possible memory storage is higher than this depending on which memory areas are used. However, for NDEF message storage, the available space is 256 bytes. 

Max URL

To make it easier to understand what can actually be stored in this user memory space, the table shows the maximum length of a URL (web address) that can be stored on that tag. This is the number of characters in your web address without the 'https://' or 'https://www.' part. Use our NFC tag memory calculator to find out which chips you might be able to use.

*For the NTAG213, we've used available memory by excluding the encoding of a lock control TLV for dynamic lock bytes. These would take an additional 5 bytes but if dynamic locking is not required (it's extremely rare that it is), then these 5 bytes can be used to increase the possible length of the URL.

What is the scan counter ?

Some NFC tags can automatically store how many times they have been scanned. This is called a scan counter. Within the chip, a small amount of reserved memory logs the scans and automatically increments on each scan. This memory space can be read independently or, in some cases, can be 'mirrored' automatically into the tag data string.

Note that if you are using the tag to count the number of visits to, say, a web page, then this isn't a good way to do it. It is possible for a user to scan the tag, increase the count, but not visit the URL stored on the tag. For example, maybe the user didn't have internet access or cancelled the pageview before the page got a chance to load. In this instance, the scan count will increase at a higher rate than the number of actual page views resulting in incorrect data. The scan counter tends to be more useful for certain security or monitoring applications than for marketing.

Password

Some NFC tags have a password feature which allows controlled access to view or change the data on the tag. From a mobile phone, an App is required for this. It's a fairly low level of security but would stop a casual viewer changing data.

Sun Authentication

The NTAG424, NTAG426, NTAG223 and NTAG224 NFC chips contains a special feature allowing sections of data to be encrypted and securely appended to the URL of the tag. This then allows the tags to be used for NFC Tag authentication where the tags cannot easily be replicated.

It's a very advanced feature and requires substantial knowledge to both encode the tags and to authenticate the tags. However, the NTAG424 are among the latest generation of authentication tags and we'd expect to see more variants soon.

Common features

All the NTAG series and the MIFARE Ultralight® chips have a common set of features such as a seven byte (14 character) unique ID (UID), universal compatibility across all current mobile phones, tag locking ability and NFC Forum compatibility.

Other NFC chips

Obviously, the ST, NTAG, ICODE and MIFARE Ultralight® chips aren't the only NFC chips on the market. EM Micoelectronics have a number of interesting chips including authentication grade and dual frequency (UHF + NFC) for more specialist applications. However, it's also important to balance your requirements against availability, price breaks and more to make sure you choose the right chip. Seritag can help, so a quick conversation with us might save a lot of problems later. 

MIFARE, MIFARE Ultralight, MIFARE Classic and MIFARE DESFire are registered trademarks of NXP B.V.