RFM24W Datasheet, PDF (12/34 Pages) List of Unclassifed Manufacturers – ISM Transceiver module

RFM24W
2. Functional Description
The RFM24W module is high-performance, low-current, wireless ISM transceivers that cover the sub-GHz bands.
The wide operating voltage range of 1.8–3.6 V and low current consumption make the RFM24W an ideal solution
for battery powered applications. The RFM24W operates as a time division duplexing (TDD) transceiver where
the device alternately transmits and receives data packets. The device uses a single-conversion mixer to
downconvert the 2/4-level FSK/GFSK or OOK/ASK modulated receive signal to a low IF frequency. Following a
programmable gain amplifier (PGA) the signal is converted to the digital domain by a high performance ∆Σ ADC
allowing filtering, demodulation, slicing, and packet handling to be performed in the built-in DSP increasing the
receiver’s performance and flexibility versus analog based architectures. The demodulated signal is output to the
system MCU through a programmable GPIO or via the standard SPI bus by reading the 64-byte RX FIFO.
A single high precision local oscillator (LO) is used for both transmit and receive modes since the transmitter and
receiver do not operate at the same time. The LO is generated by an integrated VCO and ∆Σ Fractional-N PLL
synthesizer. The synthesizer is designed to support configurable data rates from 0.123 kbps to 1 Mbps. The
RFM24W operates in the frequency bands of 142–175, 283–350, 425–525, and 850–1050 MHz with a
maximum accuracy of 57.22 Hz frequency accuracy. The transmit FSK data is modulated directly into the ∆Σ data
stream and can be shaped by a Gaussian low-pass filter to reduce unwanted spectral content.
The RFM24W is designed to support single coin cell operation with current consumption below 19 mA for +10
dBm output power. Two match topologies are available for the RFM24W, class-E and switched-current. Class-E
matching provides optimal current consumption, while switched-current matching demonstrates the best
performance over varying battery voltage with slightly higher current consumption. The PA is single-ended to
allow for easy antenna matching and low BOM cost. The PA incorporates automatic ramp-up and ramp-down
control to reduce unwanted spectral spreading. The RFM24W supports frequency hopping, TX/RX switch control,
and antenna diversity switch control to extend the link range and improve performance. Built-in antenna diversity
and support for frequency hopping can be used to further extend range and enhance performance. Antenna
diversity is completely integrated into the RFM24W and can improve the system link budget by 8–10 dB,
resulting in substantial range increases under adverse environmental conditions. A highly configurable packet
handler allows for autonomous encoding/decoding of nearly any packet structure. Additional system features,
such as an automatic wake-up timer, low battery detector, 64 byte TX/RX FIFOs, and preamble detection, reduce
overall current consumption and allows for the use of lower-cost system MCUs. An integrated temperature sensor,
power-on-reset (POR), and GPIOs further reduce overall system cost and size. The RFM24W is designed to work
with an MCU, crystal, and a few passives to create a very low-cost system.
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