SI4844-B20 Datasheet, PDF (12/27 Pages) Silicon Laboratories – BROADCAST ANALOG TUNING DIGITAL DISPLAY AM/FM/SW RADIO RECEIVER

Si4844-B20
2. Typical Application Schematic
FMI
C5
AMI
0.47u
ANT2
C5
AMI
0.47u
RFGND
T1
Optional: AM air loop antenna
C1
0.1u
RESET
To host MCU ^SDIO
SCLK
TUNE1
R1
203k 1%
SW
VR1
100k
BAND
S1
1
2
3
4
IRQ To host MCU
LNA_EN
R2
50k 1%
AM
R3
180k 1%
FM
R4
67k 1%
U1
Optional
C4
0.1u
Y1
32.768KHz
C3 C2
22p 22p
LOUT
ROUT
VDD
2.0 TO 3.6V
VDD
2.0 TO 3.6V
Optional
Notes:
1. Place C4 close to VDD2 and DBYP pins.
2. All grounds connect directly to GND plane on PCB.
3. Pin 6 and 7 leave floating.
4. To ensure proper operation and receiver performance, follow the guidelines in “AN602: Si4822/26/27/40/44 Antenna,
Schematic, Layout, and Design Guidelines.” Silicon Labs will evaluate the schematics and layouts for qualified
customers.
5. Pin 8 connects to the FM antenna interface and pin 12 connects to the AM antenna interface.
6. Place Si484x as close as possible to antenna jack and keep the FMI and AMI traces as short as possible.
7. Recommend keeping the AM ferrite loop antenna at least 5 cm away from the Si4844-B.
8. Keep the AM ferrite loot antenna away from the MCU, audio amplifier, and other circuits which have AM interference.
9. Place the transformer T1 away from any sources of interference and even away from the I/O signals of the Si4844-B.
12
Rev. 1.0