Powercast Corporation, an RF wireless power technology company, has selected Nordic’s nRF51422 Bluetooth Low Energy multiprotocol System-on-Chip for its ‘PowerSpot TX91503 wireless transmitter’, which the developer claims is the first FCC- and ISED-approved solution to provide far-field wireless power over a distance for mobile consumer electronic applications.
Employing a 915-MHz RF signal, the PowerSpot wireless transmitter outputs up to 3 Watts of Effective Isotropic Radiated Power (EIRP) (and associated ID data) that can directly power or charge up to 30 portable low-power devices - including fitness bands, wireless headphones, game controllers, hearing aids, and a variety of smartcards - that are fitted with Powercast’s patented embeddable ‘Powerharvester’ technology.
The Powerharvester solution consists of a proprietary converter chip and a boost converter chip that once integrated in end devices, harvests energy from the PowerSpot wireless transmitter as well as ambient RF energy from other sources. The chips then convert that energy to DC power that can then be used to charge batteries or directly power the enabled devices.
Acting as the main ‘brain’ of the PowerSpot TX91503 wireless transmitter, the 32-bit Arm Cortex M0 CPU-powered Nordic nRF51422 SoC makes the transmitter ‘smart’, configurable, and controllable. For example, it configures and controls the transmitter’s 915 MHz oscillator/PA subsection that feeds the power antenna and turns off the transmitter when wirelessly-connected devices are fully charged. The nRF51422 SoC also provides Bluetooth LE wireless connectivity for communication between the user’s end devices and the transmitter to monitor the battery status of connected devices. Bluetooth LE wireless connectivity also allows the user to employ a Bluetooth 4.0 (and later) smartphone or tablet to remotely monitor device charge levels and set timers for the transmitter to charge devices during certain periods, for example overnight, via Powercast’s iOS or Android companion app.
The PowerSpot wireless transmitter automatically detects compatible devices within its charging zone and stops charging when no devices are within range. The wireless transmitter can charge and power smaller, less power hungry devices - such as smart cards and basic sensors - at distances up to 24 meters while for more power hungry devices like game controllers, headphones, and smartwatches, the most suitable charging range is typically within 30cm. The transmitter itself can be mains- or USB-powered, so the ultra low power consumption of the nRF51422 SoC was important to keep the temperature of the 915-MHz subcircuit low, and enhance the efficiency of wireless power transmission.
Nordic’s nRF51422 SoC is a powerful, highly flexible multiprotocol SoC ideally suited for ANT™ and Bluetooth LE ultra low power wireless applications. The nRF51422 is built around the Arm CPU and includes 256kB/128kB Flash + 32kB/16kB RAM. The SoC is supplied with Nordic’s S310 SoftDevice, an ANT and Bluetooth LE RF protocol software ‘stack’ for building concurrent ANT and Bluetooth LE solutions.
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