KAC-8103D
3
COMPONENTS DESCRIPTION
CIRCUIT DESCRIPTION
Ref. No.
Application / Function
Operation / Condition / Compatibility
Q4,5
Mute
Generates mute drive signal and turns off LED.
Q8~11
Gate driver
Gate driver in DC/DC converter FET
Q12,13,19,20
DC/DC converter
DC/DC converter switching
Q25,26,28,42
AVR
±
15V AVR
Q29,30
Tracking when
±
15V AVR is turned OFF
Matches the trailing edge of ‘-15V’ AVR with that of ‘+15V’ AVR.
Q37,38
DC/DC converter pulse ON/OFF control
ON or OFF DC/DC converter drive waveform.
Q151
Mute
Turns off audio signal.
Q400,403
Dclass amplifier switch
Turns on or off Dclass amplifier.
Q401,402
Pulse amplification, shaping and
Q404~409
level shift
Generates signal that drives the final FET in Dclass.
Q414,415,417
Q410~413
Power amplification
High-current switching in Dclass.
Q416
HB 15V AVR
Stacking AVR to obtain High+B for Dclass.
Q603
Attenuation circuit to attenuate
Attenuates output when temperature in the set becomes too high.
input signal by 1.5dB
Q604~607
Current-voltage conversion
Converts current to voltage to detect overcurrent and sends it to the comparator.
Q608~611
Latch circuit
Detects overvoltage in output and retains the current.
■
Resonance detection and protection technique
• Measures against SP terminal’s shortening
Since resonance voltage is generated with an output LC filter,
during the time after shortening until a short circuit current is
generated, detect resonance voltage and turn D-POWER off.
• Circuit description
Resonance voltage caused by shortening is detected through
a high pass filter.
Filter characteristics is 2kHz cut-off and -18dB attenuation.
q
At 100Hz, voltage is attenuated up to -59dB of 10.6V and
peak voltage becomes 12mV.
w
At 200Hz, voltage is attenuated up to -44dB of 10.6V and
peak voltage becomes 6.7mV.
e
Since resonance voltage frequency is 3.7kHz, voltage does
not attenuate.
Therefore, only resonance voltage can be detected.
Resonance voltage
generating point
Output
Short
Output
10V
10V
15V
(2/2)
IC64
(1/2)
IC64
100k
100k
1k
22k
10k
100k
4.7k
15k
0.01u 0.033u
0.033u
2.2k
0.01u
to Dclass,
power off
control
Impedance and terminal contact resistance are in-
herent in the circuit.
Therefore, resonance voltage is generated at both
ends of a shorted C.
But resonance voltage occurs less when shorten-
ing at a low output voltage point.
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