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KAC-8070
CIRCUIT DESCRIPTION
DC/DC power supply circuit
Features:
® Clock
waveform
is changed
to pulse-width
control
system
from
pulse-width
fixed
system
for greater
AM/FM _ radiation
when
comparing
with
the
conventional amplifier.
@ The
improved
regulation
of power
supply
to the
amplifier effectively decreases the rise of heat at the
normal listening volume level.
Switching regulator control IC: uwPC494C
Block Diagram
G3) Gutput Control
Reference
{Low Voltage
Regulator
Step
Dead- Time
Control
Inv. Input
Feed-Back (3)
In the above block diagram, EA2 at pin 15, 16 is not used.
Detailed description of the circuit (Reference numbers
attached to the parts in the diagram are same as the
actual circuit.)
@ Voltage control amp (EA |) — 2-phase clock generator
VoSENSE
Wet
R20 18K
R6
VR3 5K
R5
Setting the output voltage
PWM COMP.
e@ Dead time can be set to the clock waveform for higher
reliability.
e Regulation
of the secondary
side
power
supply
is
improved from the primary side of the DC power supply
{battery)/AC (alternative).
@ Switching regulator control! IC is provided to simplify
the circuit.
Connection Diagram (Top View)
NON-
INV.
INV.
REF
OUTPUT
INPUT
INPUT
OUT CONTROL Vcc
Cr
E2
E:
(8)c.
Ei
C2
Ez
NON-
INV.
FEED-
DEAD-
Cy
Rr
GNO
Ci
INV.
INPUT
BACK
TIME
INPUT
CONTROL
2-PHASE
CLOCK
GENERATOR
C3,R10:
Decision of the
frequency in use.
arteen,
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