CC2430
10 Application Circuit
Few external components are required for the
operation of CC2430. A typical application
circuit is shown in Figure 6. Typical values and
description of external components are shown
in Table 23.
10.1 Input / output matching
The RF input/output is high impedance and
differential. The optimum differential load for
the RF port is 60 + j164 Ω4.
LNA (RX) and the PA (TX). See Input/output
matching section on page 170 for more
details.
If a balanced antenna such as a folded dipole
is used, the balun can be omitted. If the
antenna also provides a DC path from
TXRX_SWITCH pin to the RF pins, inductors
are not needed for DC bias.
When using an unbalanced antenna such as a
monopole, a balun should be used in order to
optimize performance. The balun can be
implemented using low-cost discrete inductors
and capacitors. The recommended balun
shown, consists of C341, L341, L321 and
Figure 6 shows a suggested application circuit
using a differential antenna. The antenna type
is a standard folded dipole. The dipole has a
virtual ground point; hence bias is provided
without degradation in antenna performance.
L331 together with
a
PCB microstrip
transmission line (λ/2-dipole), and will match
the RF input/output to 50 Ω. An internal T/R
switch circuit is used to switch between the
Also
refer
to
the
section
Antenna
4 This is for 2440MHz.
Considerations on page 175.
10.2 Bias resistors
The bias resistors are R221 and R261. The
bias resistor R221 is used to set an accurate
bias current for the 32 MHz crystal oscillator.
10.3 Crystal
An external 32 MHz crystal, XTAL1, with two
loading capacitors (C191 and C211) is used
for the 32 MHz crystal oscillator. See page 14
for details. The load capacitance seen by the
32 MHz crystal is given by:
sleep current consumption and accurate wake
up times. The load capacitance seen by the
32.768 kHz crystal is given by:
1
CL =
+ Cparasitic
1
1
1
+
CL =
+ Cparasitic
C441 C431
1
1
+
C191 C211
A series resistor may be used to comply with
the ESR requirement.
XTAL2 is an optional 32.768 kHz crystal, with
two loading capacitors (C441 and C431), used
for the 32.768 kHz crystal oscillator. The
32.768 kHz crystal oscillator is used in
applications where you need both very low
10.4 Voltage regulators
The on chip voltage regulators supply all 1.8 V
power supply pins and internal power supplies.
C241 and C421 are required for stability of the
regulators.
10.5 Debug interface
The debug interface pin P2_2 is connected
through pull-up resistor R451 to the power
supply. See section 12 on page 60.
CC2430 Data Sheet (rev. 2.1) SWRS036F
Page 27 of 211
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