Text preview for : SoundDock_10_TOP.pdf part of BOSE SoundDock 10 TOP BOSE Audio Sound Dock Sound Dock 10 Sounddock 10 SoundDock_10_TOP.pdf
Back to : SoundDock_10_TOP.pdf | Home
SoundDock 10 Theory of Operation
Power Amplifier
Power Amplifier electronics integrated into same PCB as 24V switching power
supply
Class `D' switching amplifiers drive 3 audio channels
TI TPA3100D2 drives stereo "twiddler" transducers
NXP TDF8599TH drives single woofer channel
(dual channel amplifier configured for mono operation with paralleled outputs)
Block Diagram
Audio Path
Continuous analog differential audio inputs from DSP (3 channels)
Power Amp ICs provide effective voltage gain of 20x for bass channel, 10x for
twiddler channels
Outputs of amplifiers are Pulse-Width-Modulated, requires 2nd order low-pass L-C
filters to reconstruct continuous signals prior to speaker loads
1
SoundDock 10 Theory of Operation
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)
Output Filters
2nd order low-pass L-C
Inductor is "planar" construction