RF IC enables keyless entry & low-power tracking

25th April 2016
Nat Bowers

Combining a sophisticated multi-channel RF transceiver with a 3D low frequency (3DLF) interface that supports ultra-low power operation, the MLX73290-A has been unveiled by Melexis. This RF IC is optimised for use in vehicle activation, logistics and IoT applications such as passive keyless entry & start, 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 3 differential receive coil inputs. This permits a typical 4µA 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 MCU, it can run in passive transponder mode and thereby support battery-less operation.

Optimised for use in the sub-GHz ISM bands, 300-960MHz, the highly integrated RF IC delivers a transmitter output from -20 to +13dBm. It has a receiver sensitivity down to -120dBm in a 15kHz channel bandwidth. A 250kb/s 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 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 highly effective passive start solution for 2-wheelers (such as motorcycles, scooters, etc.), all-terrain vehicles and secure door entry systems.

Supplied in a 5x5mm 32-lead QFN package and operating over a temperature range from -40 to +105°C, the MLX73290-A is available now.

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