Integrated RF IC for passive entry & low-power tracking systems

April 27, 2016 // By Graham Prophet
Melexis' multi-channel, programmable device, MLX73290-A, features a multi-channel RF transceiver, combined with a 3-dimensional low frequency (3DLF) interface that supports ultra-low power operation.

Through its integration of sub-GHz RF and low-frequency technologies, this RF IC is optimized for use in vehicle activation, logistics and Internet of Things (IoT) applications. These include passive keyless entry & start (PKES), secure access and low-power tracking systems, where a very-low power wake-up function together with long range, high speed RF feedback are mandated.

 

The 3DLF interface features an automatic and fully programmable scan mode, constantly polling for a valid low frequency (LF) signal on the three differential receive-coil inputs. This permits a typical 4 µA power consumption in LF detection mode. The LF-RSSI feature allows precise monitoring of the received LF field. Working in combination with the system’s host microcontroller, it can run in passive transponder mode and thereby support battery-less operation.

 

Optimized for use in the sub-GHz ISM bands, covering 300 MHz to 960 MHz, the integrated RF IC delivers a transmitter output of -20 dBm to +13 dBm. It has a receiver sensitivity down to -120 dBm in a 15 kHz channel bandwidth. A 250 kbps maximum data rate is supported. Modulation schemes that can be used are on-off keying (OOK), binary frequency shift keying (FSK), minimum shift keying (MSK), Gaussian minimum shift keying (GMSK) and Gaussian frequency shift keying (GFSK).

 

Engineers can program the MLX73290-A through its serial peripheral interface (SPI), with a multitude of different parameters being adjustable - RF output power, RF bandwidth, modulation type, LF polling mode, LF/RF packet handlers, etc. Specific application requirements can thus be addressed, without any need for compromise. Evaluation boards and software tools are available to accompany this IC, making it easier to deploy.

 

When combined with the MLX74190 high power initiator device, the MLX73290-M sub-GHz ISM transceiver and an MLX81109 LIN slave interface, the MLX73290-A becomes part of a passive start solution for 2-wheelers (such as motorcycles, scooters, etc.), all-terrain vehicles and secure door entry systems.

 

Melexis’ MLX73290-A devices