SI4720-B20 Datasheet, PDF (22/48 Pages) Silicon Laboratories – BROADCAST FM RADIO TRANSCEIVER FOR PORTABLE APPLICATIONS

Si4720/21-B20
4. Universal AM/FM RX/FM TX Application Schematic
Figure 13 shows an application schematic that supports the Si47xx family of 3 mm x 3 mm QFN products,
including the Si4702/3/4/5 FM receivers, Si471x FM transmitters, Si472x FM transceivers, and Si473x AM/FM
receivers.
R2
T5
S1
J1 HP Jack
LHEADPHONE
270 nH
System Component
D3
D4
System Component
System Component
D5
Right
Audio
Left
Audio
FB1
2.5 k @ 100 MHz
FB2
2.5 k @ 100 MHz
R16
2 k
GPIO3
C4
1 nF
GPIO2
GPIO1
FM Embedded RX/TX Antenna
R14
L1
0  10 nH
LSHORT
120 nH
C17/R21
3.3pF/0 
AM Ferrite Antenna
LFERRITE
180–
600 uH
C16
470 nF
U2
Headphone Amplifier
System Component
1 _NC
2 _FMI
3 _RFGND
4 _TXO/AMI
5 _RST
GND/RIN/DOUT ¹⁵
U1
Si47xx
LOUT/DFS ¹⁴
ROUT/DIN ¹³
GND ¹²
VDD ¹¹
Si4702/03: Populate R12, R13, R21, C14, and C15
Si4704/05/1x/2x/3x Analog: Populate C7, C8, C14
and C15 as shown
Si4704/05/1x/2x/3x Digital: Populate R16, R17,
R18, R19, and R20 as shown
VBATTERY
2.7 to 5.5 V
R13
C7/R17
0
0.39 uF/ 2 k
LIN
RIN
R12
0
C8/R18
0.39 uF/ 600 
C14/R19
0.39 uF/ 0 
VBATTERY
C1 ^{2.7 to 5.5 V}
22 nF
C15/R20
0.39 uF/ 0 
System Components
RST
SEN
SCLK
SDIO
RCLK
VIO
Figure 13. Universal AM/FM RX/FM TX Application Schematic
Following the schematic and layout recommendations detailed in “AN383: Universal Antenna Selection and Layout
Guidelines” will result in optimal performance with the minimal application schematic shown in Figure 13. “Universal
AM/FM RX/FM TX Application Schematic”. System components are those that are likely to be present for any tuner
or transmitter design.
22
Rev. 1.0