SI4820-A10 Datasheet, PDF (12/20 Pages) Silicon Laboratories – BROADCAST MECHANICAL TUNING AM/FM/SW RADIO RECEIVER

Si4820/24-A10
4.3. AM Receiver
The highly integrated Si4820/24-A10 supports
worldwide AM band reception from 504 to 1750 kHz
with five sub-bands using a digital low-IF architecture
with a minimum number of external components and no
manual alignment required. This patented architecture
allows for high-precision filtering, offering excellent
selectivity and SNR with minimum variation across the
AM band. Similar to the FM receiver, the Si4820/24-A10
optimizes sensitivity and rejection of strong interferers,
allowing better reception of weak stations.
To offer maximum flexibility, the receiver supports a
wide range of ferrite loop sticks from 180–450 µH. An
air loop antenna is supported by using a transformer to
increase the effective inductance from the air loop.
Using a 1:5 turn ratio inductor, the inductance is
increased by 25 times and easily supports all typical AM
air loop antennas, which generally vary between 10 and
20 µH.
4.4. SW Receiver
The Si4824 supports 16 short wave (SW) band
receptions from 5.60 to 22.0 MHz. Si4824 supports
extensive short wave features such as minimal discrete
components and no factory adjustments. The Si4824
supports using the FM antenna to capture short wave
signals.
4.5. Frequency Tuning
A valid channel can be found by tuning the
potentiometer that is connected to the TUNE1 and
TUNE2 pin of the Si4820/24-A10 chip.
To offer easy tuning, the Si4820/24-A10 also supports a
station LED light. It will light up the LED if the RF signal
quality passes the LED sensitivity threshold when tuned
to a valid station.
4.6. Band Select
The Si4820/24-A10 supports worldwide AM band with
five sub-bands, US/Europe/Japan/China FM band with
five sub-bands, and SW band with 16 sub-bands. For
details on band selection, refer to “AN555: Si483x-
B/Si4820/24 Antenna, Schematic, Layout, and Design
Guidelines."
4.7. Volume Control
The Si4820/24-A10 not only allows customers to use
the traditional PVR wheel volume control through an
external speaker amplifier, it also supports direct digital
volume control through pins 16 and pin 17 by using
volume up and down buttons. Refer to "AN555: Si483x-
B/Si4820/24 Antenna, Schematic, Layout, and Design
Guidelines."
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Rev. 1.0