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WINSEMI |
WS3252
WS3252 High Precision CC/CV Primary-Side PWM Controller
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
General Description
WS3252 is a high-integrated offline PWM controller,
optemized for high poformance low power AC/DC charger
and adapter adapter application.
WS3252 operates in primary-side sensing and regulation.
Consequently, opto-coupler 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
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
Typical Application Circuit
5%
Io
Icc
WS3252 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 WS3252 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.
WS3252 is available in SOT23-6 package.
Rev.A Sep.2011
Copyright@Winsemi Microelectronics Co., Ltd., All right reserved.
Pin Definition and Device Marking
WS3252
1 GND
VCC 6
2 GATE COM P 5
3 C S IN V 4
52: WS3252
Y: Year Code(0-9)
WW: Week Code (1-52)
SOT23-6
Pin Function Description
Pin
Name
Pin
Number
Pin Type
GND
1
GND
GATE
2 Gate-driven output
CS 3 Current Monitoring
INV 4 Feedback Input
COMP
VCC
5 Loop Compensation
6 Power
Function Description
Ground.
Totem-pole gate driver output for power MOSFET.
Current sense input.
The voltage feedback from auxiliary winding. Connected to
resistor divider from auxiliary winding reflecting output voltage.
PWM duty cycle is determined by EA output and current sense
signal at pin3.
Loop Compensation for CV Stability
Power supply
Block Diagram
GND 1
Gate 2
CS 3
Driver
LEB OCP
Vcc_OVP
Logic
regulator U V L O
Inter supply P O R
CLK
Generation
PW M
+& SS -
CC
Controller
-
EA 2V
+
Drop Comp
Sampler
Sampling
Controller
Steady, keep you advance
6 VCC
5 COMP
4 IN V
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