NXP PN7642: One Chip for an NFC Reader, MCU and Security

Introduction

The NXP PN7642 is a single chip that holds an NFC reader, a programmable Arm Cortex-M33 microcontroller and a security subsystem. Instead of wiring a reader IC to a separate MCU, you run your application code on the same part that talks to the tags.

If you only tap tags with a phone, you'll never buy this chip. It still matters if you want to know what sits inside a door reader, a consumables-authentication station or a smart lock. Here's what NXP says it does, and where it fits.

What the PN7642 replaces

A typical reader design uses three parts: an NFC front end, a host microcontroller that runs the protocol stack and your logic, and sometimes a secure element to hold keys. The PN7642 folds these together. NXP describes it as a single-chip solution that integrates a customizable MCU, an NFC reader and SESIP-Level 2 security.

The MCU side is an Arm Cortex-M33. According to NXP's product page, the core is listed at 45 MHz with 180 kB of user flash and 20 kB of user RAM. That's small next to a phone. It's plenty for a reader that handles a few card types and drives a lock or relay.

The tag side of this world is much simpler. A chip like the NTAG I2C tag that talks to a microcontroller is a passive part that waits for a reader. The PN7642 is the active side. It is the reader.

What it can read

NXP lists reader/writer support for ISO/IEC 14443 A and B, legacy B', FeliCa, ISO 15693 and ISO 18000 EPC-HF. The product page also names MIFARE, DESFire, NTAG and ICODE families. If you are curious about the newer secure cards a reader like this would handle, see our explainer on MIFARE DUOX.

A few other numbers from the same page:

• Output power: 2 W, with a maximum operating transmitter current of 350 mA.
• Card detection: ultra-low-power card detection at about 22 µA (typical), useful for battery-powered devices that wake only when a card arrives.
• Card emulation: ISO/IEC 14443-4A, up to 848 kbps.
• Apple support: ECP 2.0 (Apple Enhanced Contactless Polling).
• Supply and range: 2.4 to 5.5 V, with an operating temperature of -40 to +105 °C.
• Package: VFBGA64, 4.5 x 4.5 x 0.8 mm.
• Interfaces: SPI and I2C controller, I2C, I3C and SPI target, USB device, HSUART and up to 21 GPIOs.

Note the package. A 64-ball BGA is a board-design part, not something you solder on a breadboard.

Security toolbox

Security is the third leg of the name. NXP's press material cites SESIP-Level 2 certification, a security toolbox, crypto accelerators and secure key storage. The product page adds detail: hardware acceleration for symmetric and asymmetric algorithms, a secure key store for up to 13 128-bit symmetric keys (or 6 256-bit keys), and software protection against side-channel attacks.

Put simply, the keys that unlock a card or authenticate a consumable can live inside the chip rather than in your application flash. For a reader mounted on a wall where someone can get at it, that is the point.

SESIP is a certification scheme for IoT security, and a Level 2 rating is a claim about how the part was evaluated. It does not make your finished product secure on its own. Your firmware and key handling still need care.

Who it is for

NXP names physical access, consumables authentication and secure identity verification as the target uses. The product page adds smart locks, EV supply equipment, healthcare, home appliances and trusted ID readers, and it lists closed-loop payments among its consumer applications. NXP's Alasdair Ross says the chip makes it easier to integrate NFC into new or existing secure authentication solutions.

For tooling, NXP points to the MCUXpresso IDE and SDK, a development kit (OM27642) and the NFC Cockpit configuration tool.

If you only want to read tags on a desk, a USB NFC reader for a computer is the simpler route. The PN7642 pays off when you are building a product and want the reader, logic and key storage in one footprint.

Conclusion

The PN7642 is NXP's answer to a common product problem: fewer chips, fewer wires between the reader and the code that decides what to do with a tap, and keys kept in hardware. It's not a hobby part, but it explains how many readers are built. When you test your own tags with NFCore on iPhone or Android, a chip like this is often what answers on the other side.

Frequently Asked Questions

How much memory can I use on the PN7642?

NXP lists 180 kB of user flash and 20 kB of user RAM.

Is the PN7642 a payment terminal chip?

NXP's main target uses are access, authentication and identity. Its product page lists closed-loop payments among applications, but it does not position the chip as a general payment terminal, which would need its own certification.

Can a hobbyist use the PN7642?

It comes in a 4.5 x 4.5 mm VFBGA64 package, so most makers would start from NXP's development kit rather than the bare chip.