Power Supplies, Block Diagram - Bose Companion 5 Service Manual

Power Supply Block Diagram
Bass module rectifies un-regulated power VSNUB from the secondary of the line power transformer. VSNUB is,
in turn, converted to the various other potentials required by the system. Nominally 26VDC, this voltage varies
with load and line levels, but is limited to 31.5V maximum(assuming line voltage of 140V AC). This voltage is
present whenever the bass module is plugged into the wall. All the voltage level source are listed in following
table:
Node Output
Name Voltage
nominal
Vsnub +26
Vraw +14 (no
load)
+10V +10
+5V +5
+3.3V +3.3
+1.2V +1.2
SENSOR +3.0
Power Supplies
VSNUB
3.3V
U902, Q9031
Reg
Type Input from
Full wave transformer
rectifier secondary
pre- VSNUB
regulator
output
linear VSNUB
linear Vraw
switching VSNUB
switching VSNUB
series +3.3
switch
10V 1.2V
U20 U50, U51
Reg Reg
Outputs to
Vraw
Power Amplifiers, +5V, VRAWSEN.
Headphone power amplifiers, control module
green LED.
CODEC Analog power supply
DSP I/O power supply, digital supply for USB
controller, CODEC, EEROM.
DSP core power supply.
Switch able supply for control module touch
sensor, control module red LED
3
VRAW
Q10
Bose Brand FET
Quasi-Regulator
5V
U11
Reg