CC400 Chipcon, CC400 Datasheet - Page 14

• Manufacturer Part Number: CC400
• Description: Single Chip High Performance RF Reansceiver
• Manufacturer: Chipcon

Optional LC Filter
An optional LC filter may be added
between the antenna and the matching
network in certain applications. The filter
will reduce the emission of harmonics and
increase the receiver selectivity.
Crystal oscillator
An external clock signal or the internal
crystal oscillator can be used as main
frequency reference. An external clock
signal should be connected to XOSC_Q1,
while XOSC_Q2 should be left open. The
crystal frequency must be in the range 4 -
13 MHz.
Using the internal crystal oscillator, the
crystal
XOSC_Q1 and XOSC_Q2. The oscillator
is designed for parallel mode operation of
the crystal. In addition loading capacitors
(C151 and C161) for the crystal are
required. The loading capacitor values
depend on the total load capacitance, C
specified for the crystal. The total load
capacitance seen between the crystal
terminals should equal C
oscillate at the specified frequency.
Chipcon AS
C
must
L
=
C
XOSC_Q1
1
151
be
1
+
C
connected
SmartRF
1
161
L
+
for the crystal to
C53
C
Figure 10. Crystal oscillator circuit.
TM
parasitic
CC400
C151
between
L52
Figure 9. LC filter.
L
,
Datasheet (rev. 3.1) 2003-11-12
XTAL
SmartRF
The filter for use at 433.92 MHz is shown
in figure 9. The component values may
have to be optimised to include layout
parasitics. The filter is designed for 50Ω
terminations.
The parasitic capacitance is constituted by
the pins input capacitance and PCB stray
capacitance. Typically the total parasitic
capacitance
capacitor may be placed across C151 for
initial tuning if necessary.
The crystal oscillator circuit is shown in
figure 10. Typical component values for
different values of C
The initial tolerance, temperature drift,
ageing and load pulling should be carefully
specified in order to meet the required
frequency
application.
expected frequency accuracy in SmartRF
Studio
frequency separation, the software will
calculate the total bandwidth and compare
to
software will report any contradictions and
a
recommended if required.
C52
the
more
together
available
C161
accurate
accuracy
By
is
f = 433.92 MHz
C52=15 pF
C53=22 pF
L52=8.2 nH
4.5
XOSC_Q2
with
specifying
L
IF
®
are given in table 3.
pF.
crystal
bandwidth.
in
data
CC400
A
a
Page 14 of 27
the
rate
will
trimming
certain
total
The
and
be