Circuit Description Of Digital Amp. Section - Pioneer SX-SW404 Service Manual

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7.1.4 CIRCUIT DESCRIPTION OF DIGITAL AMP. SECTION

QQ
3 7 63 1515 0
TAS5508BPAG
PCM Signal
From DSP
PWM Processor section
PWM Processor section
The PCM signals output from the DSP 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.
Power Stage section
TE
L 13942296513
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.
If the detection and protection work, the ports of the power stage ICs become the following state.
Output LPF section
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.
Attention :
As a signal to drive the BTL is output from the negative speaker terminal, DO NOT short-circuit between the
negative speaker terminal and ground, such as the chassis.
Do not short-circuit between the plus speaker terminal and ground, such as the chassis, too.
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Filter
PCM → PWM
and
Volume
IC3101
Power Stage ICs No.
IC3201
IC3301
IC3401
SYSTEM
CONTROL
CONNECTOR
OUTSUB WOOFER
USE ONLY WITH
DISPLAY UNIT
x ao
CENTER
y
i
Do not short-circuit
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6
8
3.3V
0V
To UCOM
*1
XSD
*2
XOTW
TAS5142DDV
Timing
Control
Protection
IC3201, IC3301, IC3401
*1 XSD : /SD (5pin)
*2 XOTW : /OTW (2pin)
Power Stage section
Q Q
3 6 7 1 3
Protection Enable State
/SD (5pin) ⇒ L
/OTW (2pin) ⇒ L
FM
UNBAL75Ω
SPEAKERS
DVD/DVR 1
SURROUND
R L
(COAXIAL)
u163
R FRONT L
Negative Speaker Terminal
.
Ground (Chassis)
SX-SW404
6
7
2 9 9 4 2 8
30.5V
0V
Gate
Drive
Gate
Drive
Output LPF section
1 5 0 5 8 2 9 9 4
AM
LOOP ANTENNA
AUDIO INPUT
DIGITAL
DVD/DVR 2 DIGITAL ANALOG
(OPTICAL) (OPTICAL)
L
m
R
co
7
8
9 9
A
0V
B
0V
C
2 8 9 9
D
E
F
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