SI2704-A10 SILABS [Silicon Laboratories], SI2704-A10 Datasheet - Page 22

• 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
4.3.2. Output Mode Configuration (Si2705/07 only)
The Si2705/07 can be programmed via 2-Wire or configured using the OUTSEL MFP to operate in three different
output modes: 2.1 mode, 2.0 mode and aux out mode, with the 2.0 mode being the default. If OUTSEL is not
configured as OUTSEL, these output modes can instead be programmed by setting the argument
OUTSEL_MODE of the ACTIVATE command. Refer to the “AN469: Si270x Programming Guide” for more
information on the options and settings requested for the different operation modes.
OUTSEL is a three-level input with decoding to configure the analog audio signal output at AUXOL/R pins as
shown in Table 15.
For stereo implementations, the 2.0 mode is selected enabling the main channel stereo power stage outputs. This
is the default mode when OUTSEL is not externally driven, or when OUTSEL is driven to mid-level between V
and GND.
In 2.1 mode, with OUTSEL driven high to V
bridge-tied loads while a PWM DAC produces mono analog audio from the auxiliary channel to drive a subwoofer
or central channel analog input amplifier.
To drive an external stereo analog amplifier (e.g., for headphones) the PWM DAC can be configured to output the
main stereo channel. In this case, OUTSEL is driven low to GND.
To avoid unwanted audible pop noises on the output, the Si270x implements circuitry to minimize the output
transients that occur while charging and discharging the PWM DAC ac coupling capacitor (see C10 and C11 in the
typical application schematic on page 13). The click and pop noise reduction circuit controls the charging and
discharging currents on the capacitors to prevent sudden changes in the output bias level and the consequent
glitches in the output voltage.
OUTSEL can be driven by a headphone plug detection circuit as shown in Figure 16. The ratio between the two
resistors in the diagram configures the outputs for a 2.0 (with R1=R2) or a 2.1 application (with R2>>R1). In this
application example, OUTSEL may be used for enabling and disabling the external amplifiers.
22
OUTSEL
V
GND
V
IO
IO
/2
Configuration
Aux Out Mode
2.0 Mode
2.1 Mode
Output
Figure 15. MUX OUTSEL Configuration
channel
PW M
Table 15. OUTSEL MFP Decoding
Left
1
M U X
Left
AU XO L
IO
2
H-Bridge Amplifier
, the main channel stereo power stage is enabled to drive stereo
Stereo PW M D AC
O U TSEL
Rev. 0.6
disable
enable
enable
channel
PW M
Aux
AU XO R
2
M U X
R ight
channel
(mono aux out)
Analog Output
PW M
R ight
Aux Channel
Description
1
disable
disable
enable
(stereo aux out)
Analog Output
Main Channel
disable
disable
enable
IO