Datasheet

© 2009-2011 Microchip Technology Inc. Preliminary DS70590C-page 73
MRF49XA
4.0 APPLICATION DETAILS
The application circuit of MRF49XA with a balun circuit
is shown in Figure 4-1.
FIGURE 4-1: APPLICATION CIRCUIT
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
1
2
3
4
16
15
14
13
12
11
10
9
5
6
7
8
MRF49XA
RC7
RC6
RC5
RC4
RC3
RC2
RC1
RC0
OSC1
PIC
®
MCU
C4*
2.2 nF
C1
2.2 uF
V DD
C3
0.01 uF
C2
(see
Table 2-2)
50 Ohm Loop
Antenna
X1
10 MHz
* Connections are optional.
MCLR
_____
SDI
SCK
SDO
RCLKOUT/FCAP/FINT*
CLKOUT*
Balun
INT/D IO*
IRO
CS
FSK/DATA/FSEL*
RESET*
+3.3V
C5 C6
50
Ω
ANT
J1
L1
L2 L3
RFN
RFP
Freq.
L1 L2 L3 C5
C6
C7
433 MHz
390 nH
33 nH 47 nH 68 pF2.7 pF 5.1 pF
868 MHz
100 nH
8.2 nH
22 nH
1.2 pF 27 pF
2.7 pF
915 MHz
100 nH
8.2 nH
22 nH 1.2 pF 27 pF
2.7 pF
C7