SI4827-A10 Datasheet, PDF (15/25 Pages) Silicon Laboratories – BROADCAST ANALOG TUNING DIGITAL DISPLAY AM/FM/SW RADIO RECEIVER

Si4827-A10
4.7. Bass and Treble
The Si4827-A10 supports Bass/Treble tone control for
superior sound quality. The Si4827-A10 can be set to be
default normal, or programmed by the host MCU I²C-
compatible 2-wire mode. FM has nine levels
Bass/Treble effect and AM/SW has seven levels
Bass/Treble effect. For further configuration details,
refer to "AN610: Si48xx ATDD Programming Guide".
4.8. Volume Control
The Si4827-A10 not only allows users to use the
traditional PVR wheel volume control through an
external speaker amplifier, it also supports digital
volume control programmed by the host MCU. Si4827-
A10 can be programmed to be Bass/Treble mode only
or digital volume mode only; it can also be programmed
to have the digital volume coexist with Bass/Treble in
two modes. Refer to "AN610: Si48xx ATDD
Programming Guide" and "AN602: Si4822/26/27/40/44
Antenna, Schematic, Layout, and Design Guidelines"
for more details.
4.9. High Fidelity DAC
High-fidelity digital-to-analog converters (DACs) drive
analog audio signals onto the AOUT pin. The audio
output may be muted.
4.10. Soft Mute
The soft mute feature is available to attenuate the audio
outputs and minimize audible noise in very weak signal
conditions. Advanced algorithm is implemented to get a
better analog tuning experience. The soft mute feature
is triggered by the SNR metric. The SNR threshold for
activating soft mute is programmable, as are soft mute
attenuation levels and attack and decay rates.
4.11. Reference Clock
The Si4827-A10 supports RCLK input (to XTALI pin)
with the spec listed in Table 7. It can be shared with the
host MCU to save extra crystal.
An onboard crystal oscillator is available to generate the
32.768 kHz reference when an external crystal and
load capacitors are provided. Refer to "AN602:
Si4822/26/27/40/44 Antenna, Schematic, Layout, and
Design Guidelines" for more details.
4.12. Reset, Powerup, and Powerdown
Setting the RSTB pin low will disable analog and digital
circuitry, reset the registers to their default settings, and
disable the bus. Setting the RSTB pin high will bring the
device out of reset.
Figure 1 shows typical reset, startup, and shutdown
timings for the Si4827. RSTB must be held low
(asserted) during any power supply transitions and kept
asserted as specified in Figure 1 after the power
supplies are ramped up and stable. Failure to assert
RSTB as indicated here may cause the device to
malfunction and may result in permanent device
damage.
A powerdown mode is available to reduce power
consumption when the part is idle. Putting the device in
powerdown mode will disable analog and digital circuitry
while keeping the bus active.
4.13. Memorizing Status
The Si4827-A10 provides the feature to memorize
status from the last power down with a simple design on
PCB, including frequency of the FM/AM/SW station.
Refer to "AN602: Si4822/26/27/40/44 Antenna,
Schematic, Layout, and Design Guidelines" for details.
4.14. Programming with Commands
To ease development time and offer maximum
customization, the Si4827 provides a simple yet
powerful software interface to program the receiver. The
device is programmed using commands, arguments,
properties, and responses.
To perform an action, the user writes a command byte
and associated arguments, causing the chip to execute
the given command. Commands control an action such
as powerup the device, shut down the device, or get the
current tuned frequency. Arguments are specific to a
given command and are used to modify the command.
Properties are a special command argument used to
modify the default chip operation and are generally
configured immediately after powerup. Examples of
properties are de-emphasis level and soft mute
attenuation threshold.
Responses provide the user information and are
echoed after a command and associated arguments are
issued. All commands provide a 1-byte status update,
indicating interrupt and clear-to-send status information.
For a detailed description of the commands and
properties for the Si4827, see "AN610: Si48xx ATDD
Programming Guide".
Rev. 1.0
15