Bluetooth proximity key fob is smaller than a credit card and runs for a year off a coin cell

Dayton Industrial Co. Ltd has announced a Bluetooth low energy proximity key fob based on Nordic‘s µBlue nRF8002 System-on-Chip (SoC) that is less than half the size of a credit card.

The nRF8002’s low power performance and size will enable the Dayton Bluetooth low energy proximity key fob to run for around a year from a regular 3V CR2025 lithium coin cell battery under typical (daily) usage conditions while featuring an extremely slim (0.5cm-thick) and compact (4.9 x 3.2cm) plastic sensor housing that features a single push button and two submerged LED status lights (one red to signal alerts, and one green to signal pairing status) within a product that weighs less than 40g. There are also additional micro-vibrator and buzzer alert options.

This production-ready product platform will allow OEMs and developers to develop a whole new range of both standard (Bluetooth v4.0 profile-based) and non-standard (uniquely developed) proximity, property location and security applications (‘apps’) for use with devices that employ Bluetooth v4.0 wireless technology such as the latest iPad and the iPhone 4S.

Bluetooth low energy is a hallmark feature of the latest Bluetooth v4.0 specification and if certain qualification requirements are met can be used to develop Bluetooth Smart devices (such as wireless sensors, peripherals, and accessories) compatible with any Bluetooth Smart Ready hub product (e.g. A smartphone, tablet/computer, and other gadget).

“Designing a Bluetooth low energy key fob slim and small enough to fit into a wallet and still offer around a year of battery life was not an easy task,” admits Johnson Chan, Product Engineering Manager at Dayton. “It felt a bit like trying to fit a high end Italian sports car engine into a matchbox. We had to use a thinner CR2025 coin cell battery instead of a more conventional CR2032 to minimise weight and size. And in order to optimise the components placement within such a slim case, we had to move the battery from a more traditional on-PCB (printed circuit board) position to an alongside PCB location and specify exceptionally low profile supporting electrical components.

Chan continues: “We were also aware that such a product would need to be very robust given its ‘anywhere anytime’ potential use and offer water resistance to rain and splashing [IPX3 standard] with an operating temperature range of 0 to +50ºC and a storage temperature range of -20 to +70ºC which is extremely important if, for example, the fob is left in a car overnight in winter or during the day in the summer.

“This meant using a hermetically-sealed translucent case design to incorporate a pair of built-in flashing color LED function indicators but still allowing end users to change batteries easily via a sliding battery compartment that did not affect the water resistance or operating temperature range – which again, wasn’t very easy to do but we did eventually manage to achieve.”

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