NXP Launches UWB Chip to Turn Smartphones into Secure Digital Keys

The growing popularity of digital keys is evident as NXP unveiled its latest ultra‑wide‑band (UWB) chip, enabling smartphones to unlock cars securely. BMW, in collaboration with the Car Connectivity Consortium (CCC), is also advancing Digital Key 3.0, which incorporates UWB for a seamless user experience.

Following its September launch of a UWB chipset for mobile devices, NXP now introduces the NCJ29D5, a car‑side UWB solution. This pairing of key fob, smartphone, and vehicle UWB radios unlocks true hands‑free access and remote parking, thanks to UWB’s precise distance measurement and localization capabilities.

UWB delivers unparalleled real‑time positioning. When two UWB‑equipped devices come within range, they perform a time‑of‑flight (ToF) ranging exchange, measuring the round‑trip delay of short 2‑ns pulses across a 500 MHz bandwidth. The result is centimeter‑level accuracy, far exceeding what Wi‑Fi, Bluetooth, or GPS can provide.

According to the FiRa (Fine‑Ranging) Consortium, UWB can determine a device’s exact position—and whether it is stationary or moving—enabling context‑aware decisions. For instance, a UWB system can detect when a driver is approaching a locked door and whether the vehicle is inside or outside the threshold, ensuring the lock opens only at the correct moment.

High precision also mitigates relay attacks that compromise many modern keyless entry fobs. In a relay scenario, an attacker’s amplification of a signal would delay the response, revealing the true distance to the UWB lock. The FiRa Consortium and the IEEE 802.15.4z standard add physical‑layer protection against such attacks.

Markus Staeblein, NXP’s VP and GM of Secure Car Access, explained that the NCJ29D5 lets cars “know exactly where a user is,” providing the same convenience as premium key fobs while maintaining robust security. Users can start their vehicles with a phone left in a pocket or bag, and benefit from secure remote parking.

The new NCJ29D5 UWB chip from NXP (Source: NXP)

With the NCJ29D5, the car can detect a smartphone’s approach and, within distances defined by CCC specifications, trigger features—such as welcoming lights at eight meters and automatic unlocking within two meters—thereby delivering true hands‑free entry.

Security remains paramount. Staeblein noted that smartphones already handle high‑value transactions like mobile banking, and the Digital Key specification stores the key in a secure element on the phone and in the car’s secure microcontroller. Combined with UWB’s real‑time ToF, this architecture prevents unauthorized access.

Beyond entry, UWB opens a range of new automotive services: smartphone‑controlled valet parking, autonomous vehicle positioning for electric‑vehicle charging, on‑the‑go drive‑through payments, and seamless integration with garage doors and parking facilities.

Potential new automotive applications enabled by UWB (Source: NXP)

“The opportunities in the web of mobility are vast,” Staeblein said. “As a leading semiconductor supplier, we aim to deliver seamless and secure mobility experiences, and we are collaborating with BMW, Continental, and other CCC members to standardize UWB interoperability.”