CC2500RGPR Datasheet, PDF (18/99 Pages) Texas Instruments – Low-Cost Low-Power 2.4 GHz RF Transceiver

CC2500
balun that converts the differential RF signal
on CC2500 to a single-ended RF signal. C121
and C131 are needed for DC blocking.
Together with an appropriate LC network, the
balun components also transform the
impedance to match a 50  antenna (or
cable). Suggested values are listed in Table
15.
The balun and LC filter component values and
their placement are important to keep the
performance optimized. It is highly
recommended to follow the CC2500EM
reference design ([4]).
Crystal
The crystal oscillator uses an external crystal
with two loading capacitors (C81 and C101).
See Section 26 on page 50 for details.
Power Supply Decoupling
The power supply must be properly decoupled
close to the supply pins. Note that decoupling
capacitors are not shown in the application
circuit. The placement and the size of the
decoupling capacitors are very important to
achieve the optimum performance. The
CC2500EM reference design ([4]) should be
followed closely.
Component
C51
C81/C101
C121/C131
C122/C132
C123/C124
L121/L131
L122
R171
XTAL
Description
Decoupling capacitor for on-chip voltage regulator to digital part
Crystal loading capacitors, see Section 26 on page 50 for details
RF balun DC blocking capacitors
RF balun/matching capacitors
RF LC filter/matching capacitors
RF balun/matching inductors (inexpensive multi-layer type)
RF LC filter inductor (inexpensive multi-layer type)
Resistor for internal bias current reference
26-27 MHz crystal, see Section 26 on page 50 for details
Table 14: Overview of External Components (excluding supply decoupling capacitors)
1.8V-3.6V power supply
SI
R171
SCLK
SO
(GDO1)
GDO2
(optional)
C51
GDO0
(optional)
CSn
1 SCLK
2 SO (GDO1)
3 GDO2
4 DVDD
CC2500
DIE ATTACH PAD:
5 DCOUPL
AVDD 15
AVDD 14
RF_N 13
RF_P 12
AVDD 11
XTAL
C81
C101
L131
C131
C132
C121
L121
C122
Antenna
(50 Ohm)
L122
C123 C124
Alternative:
Folded dipole PCB
antenna (no external
components needed)
Figure 3: Typical Application and Evaluation Circuit (excluding supply decoupling capacitors)
SWRS040C
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