WS3256 Datasheet, PDF (1/9 Pages) Shenzhen Winsemi Microelectronics Co., Ltd – High Precision Primary-Side Off-line PWM Power Switch

WS3256 Product Description
High Precision Primary-Side Off-line PWM Power Switch
Features
� 5uA ultra-low startup current
� 2mA Low operating current
� ±5% Constant Voltage Regulation at Universal AC
input
� Primary-side Sensing and Regulation Without TL431
and Opto-coupler
� Programmable CV and CC Regulation
� Built-in Primary winding inductance compensation
� Programmable cable drop compensation
� Built-in soft start
� Built-in Leading-edge blanking
� Cycle by cycle over current protection (OCP)
� VCC over voltage clamp & under voltage
lockout( UVLO)
� Maximum Gate output voltage clamped at 12V
� Frequency jittering
� Ultra low standby power (<100mW)
Applications
Low power AC/DC offline SMPS for
� Cell Phone Charger
� Digital Cameras Charger
� Small Power Adapter
� Auxiliary Power for PC, TV etc.
� Linear Regulator/RCC Replacement
General Description
WS3256 is a high-integrated offline PWM controller,
optimized for high performance low power AC/DC charger
and adapter application.
WS3256 operates in primary-side sensing and regulation.
Consequently, optocoupler and TL431 could be eliminated,
thus reduce the cost. It can achieve ±5% constant voltage
precision in full input voltage range. CC/CV Control as
shown in fig.1.In CC Control, the current and output power
setting can be adjusted externally by the sense resistor Rs
at CS pin. In CV control, multi-mode operations are utilized
to achieve high performance and high efficiency. In
addition, good load regulation is achieved by the built-in
cable drop compensation. Device operates in PFM in CC
mode as well at large load condition and it operates in
PWM with frequency reduction at light/medium load.
Vo
5%
Io
Icc
Fig.1 Typical CC/CV Curve
WS3256 offers power on soft start control and protection
coverage with auto-recovery features
including Cycle-by-Cycle current limiting, VCC
OVP, VCC clamp and UVLO. The gate-driven output is
clamped to maximum 12V to protect the internal MOSFET.
Excellent EMI performance is achieved by using the
soft-switching and frequency jittering at the
totem-pole-gate-drive output. The WS3256 is the ideal
substitute of the linear power supply or the RCC-mod e
power, for a better performance of the whole switch power
system and a lower cost.
WS3256 is available in DIP-8 package.
WINSEM I M ICROELECTRONICS
WINSEM I M ICROELECTRONICS
WINSEM I M ICROELECTRONICS
Copyright@Winsemi Microelectronics Co., Ltd., All right reserved.
WINSEM I M ICROELECTRONICS
W/T-D021-Rev.A/1 May.2014
WINSEM I M ICROELECTRONICS
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