New AS3955 Provides Industry-Leading Energy Harvest Performance

Battery-free design and realization of lithium-ion battery wireless charging

May 21, 2015 – ams (Country Manager Jong-Deok Lee), a company specializing in high-performance analog ICs and sensors, announced the release of an NFC interface chip (NFiC™) (product name: AS3955) that provides proprietary energy harvesting and data transmission capabilities.

Like the existing AS3953, the new AS3955 provides a contactless connection (bridge) between an NFC reader (smartphone or tablet) and any microcontroller. In addition, the AS3955 also serves as a power supply for the host device. Specifically, it collects 5mA of energy at 4.5V from the RF energy emitted by the NFC reader, which is sufficient to fully charge a lithium-ion battery.

The AS3955 supports two bidirectional data transmission modes that designers can select. The Extended mode allows data to be transmitted from the host microcontroller with minimal processing overhead when using NFC tag commands. The second selectable mode, Tunneling mode, provides a clear and fully flexible channel between the reader and the host microcontroller, allowing users to freely implement any standard or proprietary communication protocol. Since no mode requires memory buffering in the AS3955's internal EEPROM memory, it provides faster data transfer results.

The AS3955 functions as a high-performance RF front-end that simply connects to an external NFC antenna without requiring additional external components. It includes (2 kbits or 4 kbits) EEPROM memory and SPI or I2C for communication with an external microcontroller. This device fully complies with the ISO14443A standard and NFC Forum specifications up to Level 4, and supports both Type 2 Tag standalone functionality and Type 4 Tag emulation combined with an external MCU.

The AS3955 offers unparalleled performance and flexibility by featuring superior energy and data management capabilities compared to existing interface tags on the market. Energy collected from NFC readers allows the AS3955 to operate without an external power supply. This harvested energy is also used to power external circuits. This feature enables independent, eco-friendly, battery-free designs for applications such as wireless sensor interfaces in stores or smart payment cards, interactive games and toys, and smart price tags.

A unique data management feature provided by the AS3955 is Stealth mode. Through this mode, the host MCU disables the NFiC RF channel via the I2C or SPI interface after an operation, such as Bluetooth pairing, is successfully completed. This product provides guaranteed user control over NFC operations. The AS3955 provides 32-bit password protection for EEPROM memory.

Furthermore, the AS3955 adds a new Silent mode for fail-safe Bluetooth pairing. If the host battery is insufficiently charged to power the Bluetooth mode, the AS3955 NFiC automatically shuts off the RF circuit to prevent the device from resetting the pairing process.

These outstanding energy and data management capabilities can be widely used in industrial, consumer, and gaming devices. Products can be configured on factory production lines or customized according to requirements. Fast transfer speeds and energy harvesting performance reduce the time required to download configuration data, supporting increased production output on mass manufacturing lines.

David Renno, Product Marketing Manager at ams, stated, “If you need to connect simple, slow NFC to a microcontroller, the existing interface tags currently in use may be suitable. However, thanks to its ability to function as a power supply for the host device and its high-speed data transfer modes, the AS3955 offers designers the scope to implement much more sophisticated systems. The AS3955 is designed to enable deployment in new application ranges where interface tags could not previously be used.”

The NFC interface tag IC AS3955 is currently available for mass production in a 10-pin, 3mm x 3mm MLPD package. Wafer-level chip scale package (WL-CSP) and sawn wafer are available upon request. In the WL-CSP version, the unit price is $0.98 per unit for orders of 1,000 units.

Demo boards for the AS3955 are available online at the ams ICdirect web store. For sample requests and inquiries regarding detailed technical information, please visit www.ams.com/NFC/AS395.