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What is WS9445P?

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


WS9445P Datasheet PDF - Winsemi

Part Number WS9445P
Description Non-isolated Buck Offline LED Driver
Manufacturers Winsemi 
Logo Winsemi Logo 


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WS9445P Product Description
Features
Critical Conduction Mode Operation
Internal 600V 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
External PWM Dimming
Applications
LED Bulb Lights
LED Panel Lights
LED Strings
Typical Application Circuit
Non-isolated BuckOffline LED Driver
Description
The WS9445P 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
WS9445P integrates a 600V 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 WS9445P adopts intelligent temperature control and
thoroughly solves the problem of light flashing at high
temperatures. It integrates an external dimming pin which
inputs PWM signal and can dim by changing the duty cycle of
the PWM signal. The WS9445P 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 WS9445P is available in DIP-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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WS9445P equivalent
WS9445P Product Description
Function Description
The WS9445P is a high performance non-isolated buck
converter specially designed for LED lighting. The device
integrates a 600V 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 WS9445P 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.
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 4.7uF 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
WS9445P unable to start. Strict control measures are taken
in its layout and productive process.
Constant Current Control
The WS9445P 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 WS9445P, the CS pin is connected to the current
sense 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.
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
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Part Details

On this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for WS9445P electronic component.


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Part NumberDescriptionMFRS
WS9445The function is Non-isolated Buck Offline LED Driver. WinsemiWinsemi
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