MRF49XA Datasheet, PDF (73/102 Pages) Microchip Technology – ISM Band Sub-GHz RF Transceiver

4.0 APPLICATION DETAILS
The application circuit of MRF49XA with a balun circuit
is shown in Figure 4-1.
FIGURE 4-1:
APPLICATION CIRCUIT
VDD
RC7
RC6
PIC^® M CU
RC5
RC4
RC3
RC2
RC1
RC0
OSC1
_____
MCLR
IN T/D IO *
SDI
1
SCK
2
CS
3
SDO
4
IRO
5
FSK/D ATA/FS EL*
6
R C LKO UT/FCA P/FIN T*
7
CLKOUT*
8
RESET*
C1
2.2 uF
16
15
14
13
12
11
10
9
MRF49XA
C3
0.01 uF
C2
(see
Table 2-2)
C4*
2.2 nF
B a lu n
50 Ohm Loop
A n te n n a
X1
10 MHz
* C onn ectio ns a re optional.
4.1 Antenna/Balun
A balun circuit for a 50Ω antenna is shown in
Figure 4-2. If low tolerance components (i.e., ±5%) are
used with an appropriate ground, the impedance
remains close to the 50Ω measurement.
FIGURE 4-2:
BALUN CIRCUIT
+3.3V
L1
C5
C6
RFP
L2
L3
RFN
C7
J1
50Ω ANT
Freq.
433 MHz
868 MHz
915 MHz
L1
390 nH
100 nH
100 nH
L2
33 nH
8.2 nH
8.2 nH
L3
47 nH
22 nH
22 nH
C5
2.7 pF
1.2 pF
1.2 pF
C6
68 pF
27 pF
27 pF
C7
5.1 pF
2.7 pF
2.7 pF
© 2009 Microchip Technology Inc.
Preliminary
DS70590B-page 71