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Low power FSK transceiver features simple star network management

Austriamicrosystems has introduced the AS3900 27MHz FSK (frequency shift keying) low power transceiver. The device features built-in star network management protocol, and operates in the 27MHz worldwide ISM (industrial, scientific and medical) band. Operation in this band avoids the interference found in the 2.4GHz band and results in a lower amount of energy being absorbed by the human body, which is also known as specific absorption rate. This is a key consideration for transmitters operated close to the human body, such as a body area network or a medical body area network. The transceiver features a built-in star network management protocol, which offers a hardwired, royalty-free, easy-to-use protocol for self-management of all network functions. The hardwired star network protocol simplifies product design and significantly reduces system power compared to alternative approaches requiring protocols that run full-time on an external or internal microcontroller. The low powered transceiver requires 2.5µA in polling mode, and typically 3.8 and 4.9mA in receive and transmit modes respectively, which include the power required to manage the star network.

The performance and capabilities of the device make it well suited for a number of applications where low power, short-range data exchange is required. Such applications include data transfer among devices close to a human body, such as medical and intelligent sporting goods, industrial automation, body area networks and any short range sensor network. An integrated wakeup receiver allows an ultra-low current consumption of only 2.5µA while in polling mode. The device operates with a small PCB antenna that resonates at 27MHz. Properties of 27MHz transmissions enable better penetration of fluids than 2.4GHz, and prevent reflections from giving errant range estimations using received signal strength indication. The device transmits data at up to 212Kbit/s and integrates a number of key features, resulting in a low bill of materials. Integrated functions include a power amplifier, clock, 24 bits of OTP memory, battery level detection, power on reset and system timers. Digital RSSI, onboard cyclic redundancy check and a bi-directional SDI bus (serial digital interface) allow for easy system integration. The transceiver is available in a 5x5mm, 28-pin QFN package, operates from a 2.2V power supply, and has an ambient operating temperature range from -40 to +85°C.