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KAC-PS4D/X4R
● Flow of PS4D/X4R signal line and power supply
controls
• Block diagram
The signal from the pin jack is converted into the differential
signal via the isolation amplifi er, variable resistor, and single
end.
It is converted into the digital signal in the AD converter and
it is signal-conditioned in the DSP so that it can be amplifi ed
by the PWM digital amplifi er.
It is PWM-amplifi ed to the analog signal by the driver and
power MOSFET to the level that can be output from the
speaker.
RCA IN AL
BATT14.4V
GND
● Main signal amplifi er circuit with PWM
• Main signal amplifi er circuit with PWM
The audio signal that is DA-converted is converted into the
signal for PWM in the DSP.
Its level is shifted in the IC101 and it is converted into the
PWM signal whose amplitude is +/- B. The "+" side of the
amplitude is controlled by Q101 of the PchMOSFET and the
"-" side is controlled by Q103 of the NchMOSFET.
IC101
1
8
NC1
NC8
C101
2
7
INA
OUTA
0.1
3
6
GND
VCC
C103
4
5
INB
OUTB
0.1
8
CIRCUIT DESCRIPTION
ISO A
VR
AMP
SE to DIF
DRIVER
+HV REG
LC
FUSE
FILTER
+HV
R127
82
TP184
D105
1/2W
R147 39
Q101
R105 4.7
R145 39
TP180
D107
Q103
R107
R128
33
82
TP185
1/2W
HV
The signal right after this step is converted into the digital
signal in the AD converter and is feed-backed to the DSP.
The main signal is output from SP via the low pass filter.
In addition, current of the main signal is monitored in the
over current detection circuit and when the over current is
detected the output level is controlled by the DSP.
The signal for pre-out is output to the pin jack via the DA
converter used for the pre-out.
The 14V of the battery is converted to +/-40V in the SW
regulator. The voltage is controlled in the feed-forward and
anti-pumping circuits.
DRIVER
DSP
ADC Ach
DRIVER
U-PUMP
DAC
L/R
FF
HV REG
Over current is detected by R109 and R149. The signal level
is lowered in the DSP when the over current is detected.
Q107 is used to detect the "+" side of the switching current
and Q105 is used to detect the "-" side of the current.
+HV
+3.3V
HV
TP172
L101
15uH
R109
R149
C107
0.022
0.027
220u50
1W
1W
+
L103
R111
C117
120nH
C109
390
4700P
0.47
1/2W
TH103
TH101
1/2W
R117
390
Q107
PWR FET
FILTER
FEEDBACK, DPSC, ADCS
OVERCURRENT DETECTION
RCA OUT
L/R
+HV
+3.3V
TP171
R137
47K
Q113
Q105
R151
22K
R119 4.7K
R139
Q109
10K
HV
SP OUT AL
OC DET
FD-BL
Q112
BL
12
Q111
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