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WINSEMI |
WS3254 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)
WS3254 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%
Applications
Low power AC/DC offline SMPS for
� Cell Phones/Cordless phones Charger
� Digital Cameras Charger
� Small Power Adapter
� Auxiliary Power for PC, TV etc.
� Linear Regulator/RCC Replacement
General Description
WS3254 is a high-integrated offline PWM power switch,
optimized for high performance low power AC/DC charger
and adapter application.
Io
Icc
Fig.1 Typical CC/CV Curve
WS3254 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 WS3254 is the ideal
substitute of the linear power supply or the RCC-mode power,
for a better performance of the whole switch power system
and a lower cost.
WS3254 is available in DIP8 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-D012-Rev.A/1 Jul.2013
WINSEM I M ICROELECTRONICS
0612
WS3254 Product Description
Typical Application Circuit
AC
NS
NP
VO
CO
VCC GND
COMP G ND
IN V G ra in
C S G ra in
RS W S3 2 5 4
NA U X
Pin Definition and Device Marking
WS3254 is available in DIP8 package:
1
VCC
2
COMP
3
IN V
4
CS
D IP 8
8 GND
7
GND
6
D R A IN
5
D R A IN
WS3254D8P
A1a 2C
D: DIP8 P: no Pb
A:wafer information;
1:Ver.; a: Package Code
2C:Y+M(2=2012 C=12 Month
(1,2…A=10,B=11,C=12)
Pin Function Description
Pin
Name
VCC
Pin
Number
1
COMP
2
INV
CS
DRAIN
GND
3
4
5/6
7/8
Pin Type
Function Description
Power
Loop
Compensation
Feedback Input
Current
Monitoring
Power transistor
drain
GND
Power supply
Loop Compensation for CV Stability
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 pin4.
Current sense input.
This pin connects directly to the primary lead of the transformer.
Ground
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-D012-Rev.A/1 Jul.2013
WINSEM I M ICROELECTRONICS
0612
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