CC2480_11 Datasheet, PDF (34/48 Pages) Texas Instruments – Z-Accel 2.4 GHz ZigBee Processor

CC2480
10.11 System Considerations and Guidelines
10.11.1 SRD regulations
International regulations and national laws
regulate the use of radio receivers and
transmitters. SRDs (Short Range Devices) for
license free operation are allowed to operate
in the 2.4 GHz band worldwide. The most
important regulations are ETSI EN 300 328
and EN 300 440 (Europe), FCC CFR-47 part
15.247 and 15.249 (USA), and ARIB STD-T66
(Japan).
10.11.2 Frequency hopping and multi-channel systems
The 2.4 GHz band is shared by many systems
both in industrial, office and home
environments. CC2480 uses direct sequence
spread spectrum (DSSS) as defined by [1] to
spread the output power, thereby making the
communication link more robust even in a
noisy environment.
10.11.3 Crystal accuracy and drift
A crystal accuracy of ±40 ppm is required for
compliance with IEEE 802.15.4 [1]. This
accuracy must also take ageing and
temperature drift into consideration.
A crystal with low temperature drift and low
aging could be used without further
compensation. A trimmer capacitor in the
crystal oscillator circuit (in parallel with C191 in
Figure 5) could be used to set the initial
frequency accurately.
For non-IEEE 802.15.4 systems, the robust
demodulator in CC2480 allows up to 140 ppm
10.11.4 Communication robustness
CC2480 provides very good adjacent, alternate
and co channel rejection, image frequency
suppression and blocking properties. The
CC2480 performance is significantly better than
the requirements imposed by [1]. These are
10.11.5 Communication security
The hardware encryption and authentication
operations in CC2480 enable secure
communication, which is required for many
applications. Security operations require a lot
10.11.6 Low cost systems
As the CC2480 provides 250 kbps multi-
channel performance without any external
filters, a very low cost system can be made
(e.g. two layer PCB with single-sided
component mounting).
10.11.7 Battery operated systems
In low power applications, the CC2480 should
be placed in the low-power modes PM2 or
PM3 when not active. Ultra low power
total frequency offset between the transmitter
and receiver. This could e.g. relax the
accuracy requirement to 60 ppm for each of
the devices.
Optionally in a star network topology, the full-
function device (FFD) could be equipped with
a more accurate crystal thereby relaxing the
requirement on the reduced-function device
(RFD). This can make sense in systems where
the reduced-function devices ship in higher
volumes than the full-function devices.
highly important parameters for reliable
operation in the 2.4 GHz band, since an
increasing number of devices/systems are
using this license free frequency band.
of data processing, which is costly in an 8-bit
microcontroller system. The hardware support
within CC2480 enables a high level of security
with minimum CPU processing requirements.
A differential antenna will eliminate the need
for a balun, and the DC biasing can be
achieved in the antenna topology.
consumption may be achieved since the
voltage regulators are turned off.
CC2480 Data Sheet SWRS074
Page 34 of 43