Bose SoundDock 10 Service Manual page 63

SoundDock 10 Theory of Operation
DC Offset Detection
DC Offset Detection protects against unsafe transducer overheating caused by
excessive DC voltages across voice-coil
Simple resistor summing circuit adds outputs of all three amplifier channels
together, DCF_AMP1 and DCF_AMP2 signals routed to ADC on DSP board
Microcontroller with built-in ADC continuously monitors DC voltage between
DCF_AMP1 and DCF_AMP2
Amplifiers will be disabled and unit will be placed into low power standby if voltage
on any single transducer exceeds 3 to 4V threshold for more than 2 seconds.
DSP Block Diagram
DSP Power Management
+3.3V linear regulator directly from +24V to run PIC
+3.3VS to run remainder of 3.3V logic
+5VA,B,C to run DACs, ADCs, and op-amps
+5V_DKSW to charge iPod
+6V unregulated to drive LEDs
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