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Chassis Block Diagrams
● Power factor control circuit for Lamp ballast
● Po o wer
o
actor con n trol circuit f r Lam m p ballast
NOTE :
Power factor control (P.F.C.) is performed by IC601 and the peripheral cir-
cuits. The output voltage 370V (at AC input = 230V) is supplied to the bal-
last. The output voltage is adjusted by VR1 as shown below.
IC601 FA5502M
Oscillator
R
T
Soft Start
C
CT
T
15
11
SYNC
14
OSC
+
15k
-
CUR.AMP
4.85k
R
S
Q
0.39V
S
OCP.COMP
1
16
IFB
IDET
Current Error Amplifier
● Lamp ballast circuit
LAMP STATUS TIMING CHART
Turn ON
Stable Period
ON
LAMP_STATUS
OFF
H
LAMP_ON
(LAMP CON/SYNC Signal)
L
H
RX_LAMP
Error Detect Period
(LAMP_LIT Signal)
L
H
TX_LAMP
H = ECO, L = Normal
(ECO - LPS Signal)
L
NOTE :
Lamp Driving Circuit
Turn on the LCD Projection Monitor, LAMP_ON signal becomes to "H" and the lamp is started to light.
The ballast output is about 130W at NORMAL mode or about 115W at ECO2 mode (55inch typical).
At AUTO mode, IC301 averages the luminance of the input image, then LAMP_PWM signal from IC301 is
supplied to IC1861, and Rx/Tx signals between IC1861 and the ballast unit control the output of the ballast.
Rx_LAMP signal (lamp error signal) becomes "H" and then the LCD Projection Monitor shuts down.
Turn off a LCD Projection Monitor, it shutdowns after the period of LPS mode.
LPS Mode (Low Power Shutdown)
S Mode
de
de (Lo
o
o w
ow w Pow
At LPS mode, the ballast output is keeping about 30W for about 4 minutes after turn-off.
t LPS
mode
e, the
alla
When the LCD Projection Monitor is turned on during LPS mode, the lamp is lit at once.
Output ON/OFF Control
REF
VCC
13
10
CS
11μA
UVLO
REF
5V
16.5V/8.9V
PWM.COMP
1.55V
ER.AMP
11k
MUL
OVP.COMP
1.64V
2
3
VDET
IIN-
Multiplier
DC+
GND
Turn OFF
LPS Mode
18V
LAMP ON
GND
RX_LAMP
TX_LAMP
t
utdow
wn
outpu
t is keeping about
d
ON : Hi
OFF : Low
18V
ON/OFF
C5
12
Rg1
ON/OFF
AC INPUT
3.95V/
2.8V
Vin
VC
9
OUT
8
Rg2
PWM OUTPUT
GND
7
6
-
VIN-
Voltage Error Amplifier
1.55V
+
C1
R4
VFB
5
4
OVP
Overvoltage Protection
UNIT_LAMP BALLAST
CN01
DC INPUT
FILTER
1
DC250~400V
BUFFER
3
4
DC18V
CN02
H : ON
1
L : LPS or OFF
2
3
H : Abnormality
4
ECO Mode
H : ECO
L : Normal
LPS Mode
H : LPS
L : OFF
0W f
ab ut 4 m m inutes
- 78 -
PWM COMPARATOR TIMING CHART
PWM
COMP
ARATO
R TIMI
NG CHA
V
CS
V
IFB
V
CT
OUT
pin
Boost Converter
D1
L
Q
Vo
Co
Rs
D2
R2
R3
VR1
R12
Output
Voltage
Adjustment
R11
U20B74100
FULL
IGNITION
BRIDGE
CIRCUIT
Output voltage.
At the time of a start :
2.4 - 3.2 KVp-p
CONTROL
At the time of stability : AC 70V typ. (50~120V)
Output Frequency : 180 Hz typ.
r turn-off.
RT
t
t
LAMP
BALLAST
LAMP
ASS'Y
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