22
XV-DV575
1
2
3
4
A
B
C
D
E
F
1
2
3
4
5.3 CIRCUIT DESCRIPTION OF DIGITAL AMP SECTION
Filter
and
Volume
Timing
Control
Gate
Drive
XSD
To UCOM
PCM Signal
From
DVD or ADC
3.3 V
0 V
TAS5508BPAG
PWM Processor section
PWM Processor section
Power Stage section
Power Stage section
Output LPF section
Output LPF section
TAS5122DCA
XOTW
Protection
PCM -> PWM
Gate
Drive
20 V
0 V
0 V
0 V
The PCM signals output from the DVD decoder or AD converter are input to this section, and their volume and sound quality
are digitally adjusted. At the output stage, after conversion from PCM to PWM, the signals are output to the Power stage.
In this section, timing is controlled so that the MOSFETs on the high and low sides will not be turned on simultaneously. The
voltage of the PWM signals are raised to drive the gates of the MOSFET, and the PWM signals to drive the speakers are
output from the MOSFET at the output stage. Detection and protection functions against short-circuiting of the output
signals and temperature exceeding the standard value are also provided.
The carrier elements, high-frequency signals that are unnecessary for these speakers, are eliminated. The signals passed
through the LPF will become sine-wave signals, as shown in the figure above.
Power Stage ICs No.
Protection Enable State
IC3201
SD_AB (pin 23) => L
IC3301
SD_CD (pin 24) => L
IC3401
OTW (pin 25) => L
IC3101
IC3201, IC3301, IC3401
*1 XSD
: SD_AB (pin 23), SD_CD (pin 24)
*2 XOTW : OTW (pin 25)
*1
*2
If the detection and protection work, the ports of the power stage ICs become the following state.
