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modulation schemes are supported.
2 RF power detectors provide
augmentation of radiated power
performance during transmission.
An energy harvesting interface
allows battery-less power supply by
using a solar cell in combination with
a super capacitor. This accentuates
the transceiver’s value in remote
locations where power lines are
impractical. Evaluation boards and
software tools are also available.
The MLX73290-M is supplied in 5mm
x 5mm 32-lead QFN package. It has
an operational temperature range of
-40°C to 105°C and operates from
a supply voltage in the range 2.1 to
3.6V DC. The device includes a PLL
synthesizer with 60Hz resolution,
a 256byte FIFO that can be split
128/128 for RX/TX use and a total
of 4 programmable GPIO ports
for interfacing with other system
elements.
With its carrier recovery feature
the MLX73290-M transceiver is
able to tolerate a carrier frequency
deviation of up to twice the raw
data rate (DR) usually expressed
as ±2 x DR. The Carrier Frequency
Acceptance Range (CFAR) is not
dependant on the AFC setting.
The AFC simply enables the carrier
recovery to converge to a given
value after each and every packet.
This allows the preamble length to
be reduced, if the application can
tolerate losing a few packets at the
start.
Fig. 4 illustrates the packet error
rate (PER) against CFAR. The
example here is given for a DR
of 55.6kbps with a ±50kHz FSK
deviation. As can be seen, there is
a trade-off between the preamble
length (which is the part of the
packet during which the carrier
recovery tries to converge) and the
PER.
Conclusion
Undoubtedly, as the demand for
IoT devices grows substantially,
consumers and users will put
manufacturers of these devices
under price pressure, requiring
them to reduce costs with each
generation of product. This will
inevitably lead to greater use of low-
cost crystals with wider frequency
tolerances in the sensor nodes to
achieve this goal. As designers
search for elegant solutions to this
cost / performance trade-off, the
MLX73290-M RF transceiver with its
large carrier frequency acceptance
range will become a popular
solution for IoT data collectors as
well as bidirectional network nodes.
Fig. 4: MLX73290-M CFAR (Δf) at different preamble lengths
IoT
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