Samsung LW32A23W Schematic
LCD-TV
Chassis Model
VN32EO LW32A23W
VN40EO LW40A23W
SERVICE
Manual
LCD-TV CONTENTS
Block Diagram
Wiring Diagram
Schematic Diagrams
Block Diagram
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Worldwide Full Multi-System Block diagram
LTN325W/LTN406W
Block Diagrams
LW32A23W/LW40A23W
Sound Block diagram
Block Diagrams
LW32A23W/LW40A23W
Video Block diagram
Block Diagrams
LW32A23W/LW40A23W
Power Block diagram
LCD-TV 32”, 40” Power Block diagram
Block Diagrams
LW32A23W/LW40A23W
Inverter Power Source
function
For supplying power to the control circuit,dividing the charged current of the high-voltage current source connected to the drain
during startup,and comparing VDD voltage hysteresis.
Divided into two threshold voltages VDDon to start switching and to disconnect the startup current source (normally 14.5V), and
VDDoff to stop switching and to operate the startup current source (normally 8V)
Power MOSFET source and the circuit reference ground (GND)
Power MOSFET drain.Also used during startup as the internal high-voltage current source
until the external VDD capacitor is charged.
Feedback input.Operating voltage range of 0V ~1V.Determined by the maximum MOSFET current value.
The current limit in due consideration of the maximum drain current is included in the FB pin that is connected to the source pin.
Block Diagrams
LW32A23W/LW40A23W
Backup Power Source
Viper 12A Block Diagram
Pin Functions
Name
VDD
SOURCE
DRAIN
FB
Block Diagrams
LW32A23W/LW40A23W
PFC Circuit
Operating Principles
As the stand-by power circuit starts oscillating,the control IC of the PFC circuit (L4981) is applied with Vcc
and starts oscillating. The oscillation frequency is determined by the resistance (RP824) connected to 17Pin
and the condenser (CP816) connected to 18Pin. For regulation,the output voltage is divided by resistors and
monitored by 14Pin. The 4Pin voltage, which is entered after dividing this voltage and the AC voltage by
resistors, is calculated in the IC and the command value of the main FET is prepared. Therefore, the output
voltage is controlled by the voltage determined by the dividing resistors, and the input current has the
same waveform (sine wave) as the AC voltage, producing a power factor of almost 100%.
Protections
1. Overvoltage
The circuit has an overvoltage protection function of the voltage limit type. In the event of a sudden
interruption of the input, of overshooting [overload?] during a sudden change of load,or non-control
status, this function protects the circuit by narrowing the ON width of the FET and preventing the
voltage from rising above the overvoltage setting. The overvoltage can be set with RP834, RP835, RP836
and RP840. (The power source is set to approximately 385V)
2. Overcurrent
The current is converted into the voltage value through RP831 and RP832,and monitored by 2 Pin and 8
Pin of the control IC. If the voltage of the detecting resistor rises above the set value due to an increase in
current, the pulse width is narrowed to limit the output.
3. Thermal Shutdown
Although the IC has a thermal shutdown function, a thermistor (TH) is installed on the heat-radiating fin
of the main FET and the circuit is stopped if overheated by overload, etc.
FET VDS Waveform (Input of 100V) FET VDS Waveform (Input of 230V)
Block Diagrams
LW32A23W/LW40A23W
Resonance Circuit (Power Source for Inverter)
Operating Principles
Explains the circuit of the power source for the inverter. With the operation of the MULTI block, a voltage is
generated in the ancillary windings (4-5Pin) of T804S and is applied to 1 Pin (Vcc terminal) of the resonance
circuit to start oscillation. High side FET (Q4) and low side FET (Q5) are turned on alternately, delivering
energy to the secondary circuit. For voltage regulation, the output voltage is divided along resistors and
monitored by the transistor (QI809), and the photo coupler (PC801S) is turned on or off. If the output ,
voltage rises, PC801S is turned on and draws current from 13 Pin of the resonance circuit. The switching
frequency then increases, reducing the charge period of the resonance condenser (CI811) and thereby
limiting the output voltage. On the other hand , if the output voltage decreases, no current is drawn from
13 Pin of the resonance circuit and the switching frequency decreases, extending the charge period of the
resonance condenser and thereby raising the output voltage.
Protections
1. Overvoltage
The output voltage is divided along the resistors and monitored by QI810. If the output voltage rises, the
QI810 voltage also rises, which triggers QO810 to turn PC802S on. This will increase the voltage at 5 Pin
of the resonance IC, which stops oscillation in the latch mode.
2. Overcurrent
The current flowing in the resonance condenser (CI811) is divided through CI808, converted into voltage
at the resistors (RI809, RI816) and is monitored by 3 Pin of theresonance IC. If the output current rises,
the current in the primary winding wire also rises, which triggers the voltage at 3 Pin of the IC to rise as
well. If the voltage exceeds the set value, the pulse width is narrowed to limit the current.
3. Thermal Shutdown
The resonance IC has a built-in thermal shutdown function and stops oscillation at over 125 ˚C
FET VDS Waveform of the resonance circuit
Block Diagrams
LW32A23W/LW40A23W
Main Board Supply &Sound Exclusive IC of STR-W6853
Outlines
1. A new 7 Pin package has been developed from the existing 5 Pin package. High-power MOSFET is
embedded in a small package to save space.
2. The distance between the pins of MOSFET drain & source has been widened to 1.8mm where high
voltage is applied,allowing the loading of high anti-pressure MOSFET.
3. The operation mode changes in 3 stages according to the load applied, and saves power consumption.
TFC, MBS, and pseudo-oscillation are available.
Features
1. Improvement of power efficiency through automatic conversion of operation modes the controlling MIC
part saves power consumption through a BCD processor. W6800 series changes the operation mode in 3
stages according to the load applied and saves power consumption.
1) Pseudo-oscillation under load
2) If MBS (Multi, Bottom, Skip) frequency exceeds 70 kHz under medium or small loads, the bottom is
skipped while bottom, ON is maintained.
3) If TFC (Time, Fix, Control)operation extends the ON time forcibly under St-By load, the OFF time is
controlled to lower the oscillating frequency. In the event of compulsory ON, control by external
resistors is possible.
2. Major Features
1) Embedded overcurrent protection (OCP) of pulse by pulse
2) Embedded overload protection (OLP) of latch shut down.
3) Embedded thermal shutdown function.
4) Embedded overvoltage protection for input voltage
5) Adjustable frequency for TFC operation
Block Diagrams
LW32A23W/LW40A23W
Block Diagram
Terminal Functions
Other Functions
Terminal
Number
Symbol Name and Functions
1
2
3
4
5
6
7
D
NC
S/GND
Vcc
OCD/BD
FB/OLP
RTFC
MOSFET Drain terminal
Not Connect
MOSFET Source / Ground terminal
Control circuit power input terminal
Overcurrent detection signal input terminal / Bottom detection signal input terminal
Voltage control signal input terminal / Overload protection detection terminal
Fixed ON time adjustment terminal
Symbol Functions
TSD
OVP
Thermal Shutdown Circuit
Overvoltage circuit
Block Diagrams
LW32A23W/LW40A23W
Operation of W6853
Outlines
1. MBS : Multi bottom skip (medium load area)
The circuit has the PWM reference time T=14uS, 70 kHz internally and is designed to turn on at a bottom
less than 14uS.
Note : MBS operations should not be counted in the overload, overcurrent area. (Bottom is not extended)
If the overload condition continues, OLP will be triggered to shut down the operation. Normally ,it
is not counted during startup, and if the down edge is detected only once after a count of 2, it is
considered abnormal and the oscillation is stopped.
Sub circuit
MIC internal reference time
On at a Bottom after the Reference Time that starts with ON.
On with the Bottom Count same as memorizing circuit.
Circuit
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