SX-SW77
45
5
6
7
8
5
6
7
8
C
D
F
A
B
E
7.1.4 CIRCUIT DESCRIPTION OF DIGITAL AMP. SECTION
SYSTEM
CONNECTOR
SPEAKERS
DVD/DVR 2
(OPTICAL)
CENTER
SURROUND
DVD/DVR 1
(COAXIAL)
DIGITAL
AUDIO INPUT
FM
UNBAL75
Ω
AM
LOOP ANTENNA
ANALOG
DIGITAL
(OPTICAL)
R
L
R
L
FRONT
R
L
CONTROL
OUTSUB WOOFER
USE ONLY WITH
DISPLAY UNIT
Negative Speaker Terminal
Ground (Chassis)
Do not short-circuit
Filter
and
Volume
Timing
Control
Gate
Drive
XSD
To UCOM
PCM Signal
From
DVD or ADC
3.3V
0V
TAS5508APAG
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
27.5V
0V
0V
0V
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.
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.
Power Stage ICs No.
Protection Enable State
IC3201
SD_AB (23pin)
⇒
L
IC3301
SD_CD (24pin)
⇒
L
IC3401
OTW (25pin)
⇒
L
IC3101
IC3201, IC3301, IC3401
*1 XSD
: SD_AB (23pin), SD_CD (24pin)
*2 XOTW : OTW (25pin)
If the detection and protection work, the ports of the power stage ICs become the following state.
*1
*2
Содержание SX-SW77
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