Panasonic UF-580 / UF-590 / UF-780 / UF-790 / UF-5100 / UF-6000 / UF-6100 / DX-600 / DX-800 Service Manual / Other ▷ View online
29
SEP 2005
Ve
r 3
r 3
.0
UF-
580/590/780
580/590/780
/790
UF
-5100/6
-5100/6
000/6100
DX-600/80
0
1.1.14
Power Supply Unit (L
VPS)
Block
Dia
g
g
ram of DZEA0000
57/DZEA00005
8 (For UF-580/
590/78
0/790,
DX-6
00/800
)
N0AB5GG0000
1/N0AB5
G
G00001
(For UF-5100
/6000/6
100)
INPUT
INPUT
CIRCUIT
RECTIFIER
CIRCUIT
CIRCUIT
CONVERTER
CIRCUIT
(Q100)
CIRCUIT
(Q100)
+5 VP OUTPUT
-5 VDC OUTPUT
+24 VDC OUTPUT
GND
GND
0
A-B Voltage
C
A
B
D
GND
CONTROL
CIRCUIT
OVER CURRENT
LIMITTER
ERROR DETECTION
CIRCUIT
+5 VDC
OUTPUT
CIRCUIT
CIRCUIT
+5 VP OUTPUT
GND
+5 VP OUTPUT
CIRCUIT
-5 VDC
OUTPUT
CIRCUIT
CIRCUIT
+24 VDC
OUTPUT
CIRCUIT
OUTPUT
CIRCUIT
C103
0
C-D Voltage
0
E-F, G-H Voltage
30
SEP 2005
Ver 3.0
UF-580/590/780/790
UF-5100/6000/6100
DX-600/800
DZEA000057
Input Circuit
AC line voltage travels to the rectifying circuit through the line filter. The line filter eliminates RFI noise
which may otherwise pass to the AC line from the power supply unit. It also protects the power supply
unit from transient noise which may pass into the unit from the AC line.
which may otherwise pass to the AC line from the power supply unit. It also protects the power supply
unit from transient noise which may pass into the unit from the AC line.
Rectifying Circuit
AC power is rectified by D100 and charges C103 to make high DC voltage, then supply power to
converter circuit.
Kick-on voltage for control IC (IC105) is supplied AC power through R134, R135 and R136.
Inrush current is limited by TH100.
converter circuit.
Kick-on voltage for control IC (IC105) is supplied AC power through R134, R135 and R136.
Inrush current is limited by TH100.
Converter Circuit
A IC (IC105), in combination with transformer T100, form a switching power supply circuit using the RCC
(Ringing Choke Converter) system.
As soon as power is applied to the Power Supply Unit, AC line voltage is rectified by D100 and is
smoothed by capacitor C103. The protection circuit at the time of start-up is controlled by an IC (IC105)
and resistors R134, R135 and R136.
(Ringing Choke Converter) system.
As soon as power is applied to the Power Supply Unit, AC line voltage is rectified by D100 and is
smoothed by capacitor C103. The protection circuit at the time of start-up is controlled by an IC (IC105)
and resistors R134, R135 and R136.
Ei
Eo
D102
P --- Primary Winding
S --- Secondary Winding
B --- Control Winding
S --- Secondary Winding
B --- Control Winding
T100
Q100
P
B
Control Circuit
S
+
31
SEP 2005
Ver 3.0
UF-580/590/780/790
UF-5100/6000/6100
DX-600/800
Main Switching Circuit
In the above circuit, when the main switching transistor, Q100, is turned On, input voltage, Ei, is supplied
to the primary winding of transformer T100. However, no current will flow through diode D102 of the
secondary side, due to reverse polarity of the secondary winding causing no current flow within T100.
But the transformer charges with energy. When Q100 is turned Off, the supply voltage to the primary
winding shuts off and the windings of T100 change polarity, allowing D102 to conduct, releasing the
energy accumulated in T100 to the circuit. When the energy is discharged through D102, Q100 turns on,
once again reversing the polarity on T100 windings, creating a self-oscillation circuit.
to the primary winding of transformer T100. However, no current will flow through diode D102 of the
secondary side, due to reverse polarity of the secondary winding causing no current flow within T100.
But the transformer charges with energy. When Q100 is turned Off, the supply voltage to the primary
winding shuts off and the windings of T100 change polarity, allowing D102 to conduct, releasing the
energy accumulated in T100 to the circuit. When the energy is discharged through D102, Q100 turns on,
once again reversing the polarity on T100 windings, creating a self-oscillation circuit.
In the actual circuit, the fixed output voltages are obtained by changing the winding ratio of transformer
T100. In this converter circuit, the output voltages are stabilized by controlling the duty cycle of the ON
and OFF timing of the transistor. In this power supply, the bias winding is built into the transformer. The
power supply has four outputs, +24 VDC, -5 VDC, +5 VP and +5 VDC. The +24 VDC output is protected
by the Error Detection Circuit, and the +5VDC, +5 VP and -5 VDC outputs are protected by the circuitry
inside of the voltage regulator IC.
T100. In this converter circuit, the output voltages are stabilized by controlling the duty cycle of the ON
and OFF timing of the transistor. In this power supply, the bias winding is built into the transformer. The
power supply has four outputs, +24 VDC, -5 VDC, +5 VP and +5 VDC. The +24 VDC output is protected
by the Error Detection Circuit, and the +5VDC, +5 VP and -5 VDC outputs are protected by the circuitry
inside of the voltage regulator IC.
The value of output voltage is
Eo=d/(1-d)*Ei
d=Ton/Ts
Equivalent circuit model for the RCC.
Ton : ON time of Q100
In the equivalent circuit when SW is ON, current
flows
SW L
When SW is OFF, current flows
L D RL
The value of inductance increase current between
ON period. (d*Ts)
IL=Ei/L*d*Ts . . . . . . . . . . . . . . . . . .(1)
The value of inductance decrease current between
OFF period. ((1-d)*Ts) . . . . . . . . . . . . . . . .(2)
From equation (1) and (2),
E0=d/(1-d)*Ei
flows
SW L
When SW is OFF, current flows
L D RL
The value of inductance increase current between
ON period. (d*Ts)
IL=Ei/L*d*Ts . . . . . . . . . . . . . . . . . .(1)
The value of inductance decrease current between
OFF period. ((1-d)*Ts) . . . . . . . . . . . . . . . .(2)
From equation (1) and (2),
E0=d/(1-d)*Ei
Ts : Period of oscillation
VL
VL
L
C
T100
D(D102)
Eo
Eo
Ts
dTs
RL
Ei
SW
(Q100)
T
IL
Ei
(1-d)Ts
dTs
32
SEP 2005
Ver 3.0
UF-580/590/780/790
UF-5100/6000/6100
DX-600/800
Control Circuit and Error Detection Circuit
The control circuit amplifies the output of the duty cycle according to the error voltage detected by the
Error Detection Circuit, and drives the main transistor Q100. The method used to change the duty cycle
is to change the ON time period. When the output voltage of the +24 VDC circuit rises, the current of
photo coupler PC103 increases, the output pulse width of the control circuit decreases and the ON time
period of Q100 decreases. This control circuit decides the minimum OFF time period by itself. When the
oscillation frequency becomes higher and the OFF time period becomes minimum, the OFF time period
remains unchanged and only the ON time period decreases. This way, there is a upper limit of the
oscillation frequency and the duty cycle is expanded.
Error Detection Circuit, and drives the main transistor Q100. The method used to change the duty cycle
is to change the ON time period. When the output voltage of the +24 VDC circuit rises, the current of
photo coupler PC103 increases, the output pulse width of the control circuit decreases and the ON time
period of Q100 decreases. This control circuit decides the minimum OFF time period by itself. When the
oscillation frequency becomes higher and the OFF time period becomes minimum, the OFF time period
remains unchanged and only the ON time period decreases. This way, there is a upper limit of the
oscillation frequency and the duty cycle is expanded.
Over Current Limiter (O.C.L)
The +24 VDC output is limited by Ton MAX Limiter (ON time period of transistor Q100) which is part of
the control circuit. The +5 VP, -5 VDC and +5 VDC outputs have over current limiters provided inside the
voltage regulator.
the control circuit. The +5 VP, -5 VDC and +5 VDC outputs have over current limiters provided inside the
voltage regulator.
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