Bose SoundDock 10 Service Manual page 60

Amplifier Characteristics
Supply voltage: +24V
Full scale output (after filter):
18V peak into 1.5 ohms for bass
14V peak into 3.5 ohms for twiddlers
Full scale input from DSP:
0.95V for bass
1.5V for twiddler channels
PWM switching frequency: 288kHz
Synchronized to PA_SYNCH_CLK provided by DSP
PWM modulation mode: 'BD'
Bass Amplifier Configuration
Slave mode for externally supplied clock
Internal PLL disabled
BD modulation
I2C bus disabled
Paralleled outputs
Load detection and DC offset protection disabled
Twiddler Amplifier Configuration
Slave mode for externally supplied clock
Gain set to 20dB (GAIN0 and GAIN1 pins grounded)
Uses internal PLL (cannot be disabled)
2nd order low-pass L-C
Inductor is "planar" construction – inductor windings formed by PCB traces, ferrite
core is glued to PC board
Provide large common mode inductance (20 to 50uH) needed for attenuation of
large common mode voltage swing present in BD modulated output stage
SoundDock 10 Theory of Operation
Output Filters
2