Category: LED LCD Television Repair and Service
Contents of this article
- Power supply Schematic diagram
- ICs used in the circuit
- Pin configuration of ICs
SAMSUNG BN44-00622B
VIPER12A
The VIPer12A combines a dedicated current
mode PWM controller with a high voltage Power MOSFET on the same silicon chip.
Typical applications cover off line power supplies for battery charger adapters,
standby power supplies for TV or monitors, auxiliary supplies for motor control,
etc. The internal control circuit offers the following benefits:
# Large input voltage range on the VDD pin accommodates changes in auxiliary supply voltage. This feature is well adapted to battery charger adapter configurations.
# Automatic burst mode in low load condition.
# Overvoltage protection in hiccup mode
# Large input voltage range on the VDD pin accommodates changes in auxiliary supply voltage. This feature is well adapted to battery charger adapter configurations.
# Automatic burst mode in low load condition.
# Overvoltage protection in hiccup mode
PIN CONFIGURATION
V DD - Power supply of the control
circuits. Also provides a charging current during start up thanks to a high voltage current source connected to the drain. For this purpose, an hysteresis
comparator monitors the VDD voltage and provides two thresholds:
# VDDon: Voltage value (typically 14.5V) at which the device starts switching and turns off the start up current source.
# VDDoff: Voltage value (typically 8V) at which the device stops switching and turns on the start up current source.
# VDDon: Voltage value (typically 14.5V) at which the device starts switching and turns off the start up current source.
# VDDoff: Voltage value (typically 8V) at which the device stops switching and turns on the start up current source.
SOURCE - Power MOSFET source and circuit ground
reference.
DRAIN - Power MOSFET drain. Also used by the internal high voltage current source during start up phase for charging the external VDD capacitor.
FB - Feedback input. The useful voltage range extends from 0V to 1V, and defines the peak drain MOSFET current. The current limitation, which corresponds to the maximum drain current, is obtained for a FB pin shorted to the SOURCE pin.
DRAIN - Power MOSFET drain. Also used by the internal high voltage current source during start up phase for charging the external VDD capacitor.
FB - Feedback input. The useful voltage range extends from 0V to 1V, and defines the peak drain MOSFET current. The current limitation, which corresponds to the maximum drain current, is obtained for a FB pin shorted to the SOURCE pin.
STR- W6765
The STR-W6765 is a quasi-resonant topology
IC designed for SMPS applications. It shows lower EMI noise characteristics than
conventional PWM solutions, especially at greater than 2 MHz. It also provides
a soft-switching mode to turn on the internal MOSFET at close to zero voltage
(VDS bottom point) by use of the resonant characteristic of primary inductance
and a resonant capacitor. The package is a fully molded TO-220, which contains
the controller chip (MIC) and MOSFET, enabling output power up to 52 W with
universal input or 110 W with a 230 VAC input. The bottom-skip mode skips the
first bottom of VDS and turns on the MOSFET at the second bottom point, to
minimize an increase of operating frequency at light output load, improving system-level
efficiency over the entire load range. There are two standby modes available to
reduce the input power under very light load conditions. The first is
auto-burst mode operation that is internally triggered by periodic sensing, and
the other is a manual standby mode, which is executed by clamping the secondary
output. In general applications, the manual standby mode reduces the input
power further compared to auto-burst mode. The soft-start mode minimizes surge
voltage and reduces power stress to the MOSFET and to the secondary rectifying diodes
during the start-up sequence. Various protections such as overvoltage,
overload, overcurrent, maximum on-time protections and
avalanche-energy-guaranteed MOSFET secure good systemlevel reliability.
PIN CONFIGURATION
1 D - Drain MOSFET drain
2 NC - Clipped No connection
3 S/GND - Source/ground terminal MOSFET source and ground
4 VCC - Power supply terminal Input of power supply for control circuit
5 SS/OLP - Soft Start/Overload Protection terminal Input to set delay for Overload protection and Soft Start operation
6 FB - Feedback terminal Input for Constant Voltage Control and Burst (intermittent) Mode oscillation control signals
7 OCP/BD - Overcurrent Protection/Bottom Detection Input for overcurrent detection and bottom detection signals
2 NC - Clipped No connection
3 S/GND - Source/ground terminal MOSFET source and ground
4 VCC - Power supply terminal Input of power supply for control circuit
5 SS/OLP - Soft Start/Overload Protection terminal Input to set delay for Overload protection and Soft Start operation
6 FB - Feedback terminal Input for Constant Voltage Control and Burst (intermittent) Mode oscillation control signals
7 OCP/BD - Overcurrent Protection/Bottom Detection Input for overcurrent detection and bottom detection signals
ICE1PCS02
The ICE1PCS02/G is a 8-pin wide input range
controller IC for active power factor correction converters. It is designed for
converters in boost topology, and requires few external components. Its power
supply is recommended to be provided by an external auxiliary supply which will
switch on and off the IC. The IC operates in the CCM with average current
control, and in DCM only under light load condition. The switching frequency is
trimmed and fixed internally at 65kHz. Both current and voltage loop
compensations are done externally to allow full user control. There are various
protection features incorporated to ensure safe system operation conditions.
The internal reference is trimmed (5V+2%) to ensure precise protection and output
control level. The ICE1PCS02/G is a design variant of ICE1PCS01 to incorporate
the new input brown-out protection function and optimised to have a faster
startup time with controlled peak startup current.
PIN CONFIGURATION
1 GND - IC Ground
2 ICOMP - Current Loop Compensation
3 ISENSE - Current Sense Input
4 VINS - Brown-out Sense Input
5 VCOMP - Voltage Loop Compensation
6 VSENSE - VOUT Sense (Feedback) Input
7 VCC - IC Supply Voltage
8 GATE - Gate Drive Output
2 ICOMP - Current Loop Compensation
3 ISENSE - Current Sense Input
4 VINS - Brown-out Sense Input
5 VCOMP - Voltage Loop Compensation
6 VSENSE - VOUT Sense (Feedback) Input
7 VCC - IC Supply Voltage
8 GATE - Gate Drive Output
POWER SUPPLY SCHEMATIC DIAGRAM
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