SAMSUNG BN44-00622B Power supply board schematic diagram - Viper12a - STR-W6765 - ICE1PCS02 - LCD television repair and service

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

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.

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.

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

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

POWER SUPPLY SCHEMATIC DIAGRAM