Mitsubishi Electric LT-3280 Service Manual page 30

3 . 3 . 3 . 3 . 3 . Power circuit Power circuit Power circuit Power circuit Power circuit
For power supply of LT-3280D and LT-3780D, there are the power supply of "always on" and "ON/OFF" with a
control signal.(Refer to BLOCK POWER.pdf)
PCB Power
source
signal
POWER-
SUB1
POWER-
SUB2
POWER
S3.3V
AMPVC
MAIN A3.3V
D3.3V
AD3.3V
D2.5V
A1.8V
(O)IC9A1, IC901(Only 32") :
Power supply control IC(power factor correction) (FA5500/FA5501 : FUJI)
This IC are control IC for a power factor correction converter using critical conduction mode of
operation. This IC performs a power factor correction by conversion the current waveform from
triangle waveform to sine waveform. This IC and circuit is the same as LT-4260.
(P)IC9A2, IC902(Only 32") : Power supply voltage control IC (F9222 : FUJI)
This IC controls the power supply voltage by switching about 75KHz.
This IC has MOSFET inside IC, keep switching on and off, and controls its duty to be stable output
voltage. . This IC and circuit is the same as LT-4260.
(Q)IC920(Only 37") : Power supply voltage control IC (STR-G9628 : SANKEN)
This IC controls the power supply voltage by switching above 50kHz.
This IC has MOSFET inside IC, keep switching on and off, and controls its frequency to be stable output
voltage. And the duty is determined by input AC power voltage.
MODELS: LT-3280D/LT-3780D
Voltage "always on"
[V ] or "ON/OFF"
120V 120V ON/OFF
24V 24 ON/OFF
24V 24 always on
18V 18 ON/OFF
P5V 5 ON/OFF
S8V 8 always on
S5V 5 always on
3.3 always on
17 ON/OFF
C
4.5V 4.5 ON/OFF
3.3 ON/OFF
3.3 ON/OFF
3.3 ON/OFF
2.5 ON/OFF
1.8 ON/OFF
Control Output
signal IC
Psave1
Psave1
-
Psave4 IC9B5
Psave4 IC9B6
- IC9B4
- IC9B7
- IC830
Psave3 IC9B3
Psave2 IC9B2
Psave2 IC9000
Psave2 IC9010
Psave2 IC9020
Psave2.5 IC9030
Psave2.5 IC9040
Page 30
Note
For inverter.
Only 37"
For inverter.
Only 32"
For MAIN
Only 37"
Only 32"