SI2704-A10 SILABS [Silicon Laboratories], SI2704-A10 Datasheet - Page 28

• Manufacturer Part Number: SI2704-A10
• Description: EMI MITIGATING 2.1X 5 W CLASS D AUDIO AMPLIFIER
• Manufacturer: SILABS [Silicon Laboratories]

Si2704/05/06/07-A10
4.6.3. De-Emphasis (Si2706/07 only)
The Si2706/07 features a de-emphasis filtering option in order to be able to process recorded audio that for noise
reasons has been subject to 50/15 µs pre-emphasis. The 50/15 µs filter implemented has corner frequencies at
3.183 kHz and 10.610 kHz.
4.6.4. Crossover Filter (Si2706/07 only)
The Si2706/07 features a programmable frequency 12 dB/octave Linkwitz-Riley type crossover filter that provides
separation of the low and high frequency content of the audio signal. The filter high-pass output is used to drive the
Left/Right main channel and the low-pass output feeds the Aux Channel to be used in 2.1 Mode with an external
subwoofer power driver. The cutoff frequency can be programmed from 80 to 320 Hz in 40 Hz steps via the 2-Wire
interface by setting the CROSSOVER_FREQ property. The same property can also be used to disable and bypass
the crossover filter.
4.6.5. Digital Volume Controls
The volume control maintains a master volume for all the channels, including the Left/Right main channels and the
Aux Channel. The channel volume can be set in 0.5 dB gain/attenuation steps ranging from –100 dB (mute level)
to +28 dB using the VOLUME_MASTER property.
To prevent audible artifacts due to volume transitions, the slope of the change in volume can be programmed by
configuring the VOLUME_RAMP property. The default configuration is 0.1 dB/ms (dB per millisecond) and
programming can be done in 0.1 dB/ms steps and ranging from 0.1 to 6.3 dB/ms.
The device also provides balance control between the Left and Right channels through the use of the
VOLUME_BALANCE property. This property specifies the audio gain/attenuation division in terms of percent split
between the two channels.
The Aux Channel volume control specifies the percentage of gain/attenuation levels relative to the master volume
using the VOLUME_AUX_CHANNEL property.
Mute is implemented using the VOLUME_MUTE. Un-muting returns the volume setting to the value stored in the
volume registers at the programmed volume transition slope rate. During the mute condition, the PWM outputs
switch at a 50% duty cycle.
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