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What is WS9441?

This electronic component, produced by the manufacturer "Winsemi", performs the same function as "Non-isolated Buck Offline LED Driver".


WS9441 Datasheet PDF - Winsemi

Part Number WS9441
Description Non-isolated Buck Offline LED Driver
Manufacturers Winsemi 
Logo Winsemi Logo 


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WS9441 Product Description
Features
Critical Conduction Mode Operation
Internal 500V Power MOSFET
Gate Drive and No Auxiliary Winding
±3% LED Current Accuracy
Efficiency up to 93%
LED Short Circuit Protection
LED Open Circuit Protection
Current Sense Resistor Short Protection
Thermal Regulation Function
Applications
LED Bulb Lights
LED Panel Lights
LED Strings
Typical Application Circuit
Non-isolated BuckOffline LED Driver
Description
The WS9441 is a high precision buck constant current LED
driver and is applied to non-isolated buck LED power system with
AC input voltage of 85VAC-265VAC. The WS9441 integrates a
500V power MOSFET, and can achieve excellent constant current
performance with very few external components, so the system
cost and size are minimized. The driver operates in critical
conduction mode, and the output current does not change with the
inductance and LED output voltage. The operating current of the
IC is 200uA, so it doesn’t need the auxiliary winding for supplying
the chip, thus simplifying design and reducing cost.
The WS9441 adopts intelligent temperature control and
thoroughly solves the problem of light flashing at high
temperatures. The WS9441 offers full protection functions to
improve the system reliability, including LED open circuit
protection, LED short circuit protection, CS resistor short circuit
protection and thermal regulation function.
The WS9441 is available in SOP-7 Package.
WINSEMI MICROELECTRONICS
WINSEMI MICROELECTRONICS
WINSEMI MICROELECTRONICS
Copyright@Winsemi Microelectronics Co., Ltd., All right reserved.
WINSEMI MICROELECTRONICS
WINSEMI MICROELECTRONICS
0318

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WS9441 equivalent
WS9441 Product Description
Function Description
The WS9441 is a high performance non-isolated buck
converter specially designed for LED lighting. The device
integrates a 500V power MOSFET. With the help of
advanced constant current control and gate drive technology,
the converter achieves excellent constant current
performance with very few external components. It does not
need auxiliary winding for powering the IC or voltage sensing,
hence the system size and cost is greatly reduced.
Start Up
After system powered on, the VCC pin capacitor is
charged up by the start up resistor. When the VCC pin
voltage reaches the turn on threshold, the internal circuits
start operating. The WS9441 integrates a 17V ZENER diode
to clamp the VCC voltage. Due to the ultra-low operating
current, the auxiliary winding is not needed to supply the IC.
The typical value of the start-up current is 200uA (the
maximum value is 300uA). For the application of 176VAC
264VAC, the start-up resistor can be calculated by the
equation:
RST
VIN
_ MIN
I ST _
1.414
MAX
176 1.414
270
910K
Two resistors in 1206 size SMD can be used in series.
comparator, and the voltage on CS pin is compared with the
internal 400mV reference voltage. The MOSFET will be
switched off when the voltage on CS pin reaches the threshold.
The CS comparator includes a 350ns leading edge blanking
time.
The peak inductor current is calculated by the equation:
I PK
400 (mA)
RCS
Where, RCS is the current sense resistor value.
The current in LED can be calculated by the equation:
I LED
I PK
2
(mA)
Where, IPK is the peak current of the inductor.
Freewheeling Diode
The diode will bear the reverse voltage equal to the
input voltage when the MOSFET is on. A 600V diode was
suggested to use. Besides, the operating frequency of
freewheeling diode is from 20K to 120 KHz, such ultra fast
recovery diodes as ES and ER whose Trr is less than 50ns are
good choice.
VCC Capacitor Selection
The Vcc capacitor is used to bypass noise to IC, so that
to assure its stable operation, and should be as close as
possible to the chip.
A 1uF or above capacitor can be used in Vcc. If
selecting MLCC, the material of X7R will be used to satisfy
the stability of the capacity under high temperatures. Due to
external damage resulted from small volume and brittle
texture of MLCC, the Vcc is easy to leakage currents, which
will make the WS9441 unable to start. Strict control
measures are taken in its layout and productive process.
Constant Current Control
The WS9441 utilizes proprietary current control method.
It can achieve precise LED output current with a few external
components. Cycle by Cycle current sense is adopted in
WS9441, the CS pin is connected to the current sense
Input Electrolytic Capacitor
Input voltage should be considered in to the capacitor
pressure, and the common value is 400V.
In general, the capacity design can be calculated by the
following empirical equations:
90Vac~264Vac: 1W output uses1uF buck electrolytic
capacitor;
176Vac~264Vac: 1W output uses 0.5uF buck electrolytic
capacitor.
Output Capacitor
Electrolytic capacitor is recommended to be used. Its
stable capacitance can improve the efficiency of power supply,
the LED ripple current and luminous efficiency.
Vovp voltage should be considered in output capacitor
pressure.
WINSEMI MICROELECTRONICS
WINSEMI MICROELECTRONICS
WINSEMI MICROELECTRONICS
www.winsemi.com Tel : +86-755-8250 6288 Fax : +86-755-8250 6299
WINSEMI MICROELECTRONICS
WINSEMI MICROELECTRONICS
5/9


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On this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for WS9441 electronic component.


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