Bose Companion 5 Service Manual page 51

USB Input
6
D-
7
D+
USB Controller and
5V 25
Audio clock
master
REMOTE
MUTE
TOUCH
SENSOR
Volume
Aux In
Headphone
CODEC
The Codec, U4000, is an AKM4626A. It features the ability to be either hardwired or serial interface configurable.
For this application, it is configured by hardwiring the pins.
Stand-by Operation
DSPRESET\ is used to power down some of the internal functions of the CODEC in order to conserve power
during stand-by operation. The CODEC is active at all other times
CODEC Audio Inputs and Outputs
The DSP receives warning of a USB audio data checksum error on the BADDATA input, U7000.138. All other
connections to the USB controller and DSP are to implement the TDM audio path.
Six channels of audio output are provided by the CODEC. These six outputs are filtered to remove out-of-band
noise and attenuated 7.5dB to reduce the overall gain of the system and AC coupled to the six power amplifiers
in IC's U150, U250, and U350. The outputs are single-ended biased to approximately 2.5 volts. The maximum
amplitude for a full-scale digital input signal is approximately 1 volt rms. Of the six channels output by the
CODEC, only five are wired to the Amplifiers. The DAC_BASS1 channel (U4000.23) is used to drive both bass
amplifiers. DAC_LC (U4000.27) and DAC_RC (U4000.28) are also used to drive the headphone amplifiers
(U1000).
Aux Audio Input
The AUX stereo input from the control module is attenuated by -4.3dB. This prevents a
2.0Vrms sine wave input signal from clipping the ADC input, whose max input is 1.0 to 1.1 volts
rms. The converted stereo signal is transmitted to the DSP over the TDM path described in the
next section.
Audio Path (continued)
3.3V
U6000
38
TAS1020B
Microprocessor
EEPROM
I2C Bus
31
138
BADDATA
30 127
26
DSPINT
Q6101
RAMP
GENERATOR
VRAW
Bass Knob
U1000
EEPROM
3.3V 1.2V
I2C Bus
135
131
McASPs
134
U7000
122
TI DSP
CCLIP
TMS320DA710
126
BSCLIP
Audio clock
slave
113 115 116
120 119
Thermistor
RT6307
Q6202
Q6203
Thermistor
RT6206
18
5V 3.3V
9 6
27
DACs
ADCs
28
U4000
WM8772 or AK4626 o 25
Out to
CODEC D
23
Amplifier
26
24
Audio clock
slave
Audio Path