WS3441A ProductDescription Non-isolated Buck Offline LED Driver Features Description Critical Conduction Mode Operation The WS3441A is a high precision buck constant current Internal 500V Power MOSFET LED driver. The device operates in critical conduction mode No Auxiliary Winding and is suitable for 85Vac~265Vac universal input offline LED Ultra Low Operating Current lighting. ±3% LED Output Current Accuracy Efficiency up to 93% operating current of the IC is very low. So it doesn’t need the LED Open Protection auxiliary winding for supplying the chip. It can achieve LED Short Protection excellent constant current performance with very few external Current Sensing Resistor Short Protection components, so the system cost and size are minimized. Thermal Regulation Function The WS3441A utilizes patent pending current control Available in SOP-8 Package method. It can achieve precise output current and excellent The WS3441A integrates a 500V power MOSFET. The line regulation. The driver operates in critical conduction mode, the output current does not change with the inductance Applications and LED output voltage. LED Candle Light The WS3441A offers rich protection functions to improve LED Bulb, Spot Light the system reliability, including LED open circuit protection, T8/T10 LED String LED short circuit protection, VCC under voltage protection, Other LED Lighting CS resistor short circuit protection and thermal regulation function. The WS3441A is available in SOP-8 Package. Typical Application Attention：A 22pF capacitor can be parallel with Rovp and a resistor can be parallel with the Vcc capacitor. WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS Copyright@WinsemiMicroelectronics Co.,Ltd.,All rightreserved WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS 1105 WS3441A ProductDescription Pin Configuration and Marking Information The WS3441A is available in SOP-8 Package，the top marking is shown as below: WS3441AS8P A：Product Code X：Internal Code BCY：Internal Code For QC YMX：D/C Pin Definition Name Pin No. Description GND 1 Ground ROVP 2 Over Voltage Protection Setting Pin. Connect a resistor to GND NC 3 No Connection. Should be connected to GND(Pin1) VCC 4 Power Supply Pin DRAIN 5/6 Internal HV Power MOSFET Drain. CS 7/8 Current Sense Pin. Connect a sense resistor between this pin and GND pin. Internal Block Diagram WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS www.winsemi.com Tel : +86-755-8250 6288 WINSEMI MICROELECTRONICS Fax : +86-755-8250 6299 WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS 2/8 WS3441A ProductDescription Ordering Information Package 8-Pin SOP-8, Pb-free Marking Part Number WS3441AS8P WS3441AS8P Recommended Operation Conditions Part Number Package WS3441AS8P SOP8 Input voltage Maximum output power 175VAC-264VAC 150V/120mA 90VAC-264VAC 60V/150mA Absolute Maximum Ratings symbol paramete Range unit VDS Internal HV MOSFET drain voltage -0.3~500 V ICC_MAX VCC pin maximum sink current 2.5 V VROVP Over-voltage setting pin voltage -0.3~7 V VSOURCE Internal HV MOSFET source voltage -0.3~8 V VCS Current sense pin input voltage -0.3~7 V PDMAX Power dissipation 0.5 W TJ Operating junction temperature 165 ℃ TSTG Storage temperature range -55~165 ℃ Note : Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS www.winsemi.com Tel : +86-755-8250 6288 WINSEMI MICROELECTRONICS Fax : +86-755-8250 6299 WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS 3/8 WS3441A ProductDescription Electrical Characteristics (Unless otherwise specified, VCC=7V and TA =25 ℃) Symbol Parameter Conditions Min Typ Max Units Supply Voltage Section Vcc_clamp VCC Clamp Voltage Ivcc=1mA 7.3 V Icc_clamp VCC Clamp current VCC_ST VCC Turn On Threshold VCC Rising 6.9 V Vuvlo_HYS VCC Turn off Hysteresis VCC Falling 1.5 V Ist VCC Startup Current VCC<VCC_ST-0.5V 230 Iop VCC Operating Current 2.5 270 200 mA uA uA Current Sense Section Vcs_th TLEB Threshold Voltage for Peak 390 Current Limit Leading Edge Blanking Time for Current Sense TDELAY Switch Off Delay Time 400 410 mV 350 ns 300 ns Internal Time Control Section TOFF_MIN Minimum OFF Time 3 us TOFF_MAX Maximum OFF Time 340 us TON_MAX Maximum On Time 53 us MOSFET Section Static Drain-source RDSON VDS_BD Vcc=7V/Id=0.5A On-resistance Drain-Source Breakdown Vgs=0V/Id=250uA Voltage Power MOSFET Drain Idss Leakage Current 12.8 16 500 ohm V Vgs=0V/Vds=500V 10 uA ROVP section VROVP ROVP Pin Voltage 0.5 V Thermal Regulation Section TSD TSD_HYS T_comp WINSEMI Thermal Shutdown Temperature Thermal Shutdown Hysteresis 20 Thermal Regulation WINSEMI MICROELECTRONICS www.winsemi.com Tel : +86-755-8250 6288 ℃ ℃ 150 Temperature MICROELECTRONICS ℃ 160 WINSEMI MICROELECTRONICS Fax : +86-755-8250 6299 WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS 4/8 WS3441A ProductDescription Application Information t on The WS3441A is a high performance non-isolated Buck converter specially designed for LED lighting. The device L IPK VIN VLED integrates a 500V power MOSFET. With very few external Where, components, the converter achieves excellent constant L is the inductance value current control. And it does not need auxiliary winding for VIN is the DC bus voltage after the rectifier bridge powering the IC or voltage sensing, hence the system size VLED is the voltage on the LED and cost is greatly reduced. After the power MOSFET is switched off, the current in the inductor decreases. When the inductor current reaches Start Up zero, the power MOSFET is turned on again by IC internal After system powered up, the VCC pin capacitor is logic. The off time of the MOSFET is given by: charged up by the start up resistor. When the VCC pin t off voltage reaches the turn on threshold, the internal circuits start operating. The WS3441A integrates a 17V zener diode to clamp the VCC voltage. Due to the ultra-low operating The inductance can be calculated by the equation: current, the auxiliary winding is not needed to supply the IC. L The maximum value of the startup current is 270uA. For the application of 176VAC — 264VAC, the startup resistor can be be calculated by the equation: Rst Vin _ min 1.414 I st _ max L IPK VLED VLED (VIN VLED ) f IPK VIN The f is the system switching frequency, which is 176V 1.414 920k 270uA proportional to the input voltage. So the minimum switching frequency is set at lowest input voltage, and the maximum switching frequency is set at highest input voltage. The minimum and maximum off time of WS3441A is set at 3us and 340us, respectively. Referring to the equation of Constant Current Control Cycle by Cycle current sense is adopted in WS3441A, Toff calculation, if the inductance is too small, the Toff may the CS pin is connected to the current sense comparator, be smaller than the minimum off time, system will operate in and the voltage on CS pin is compared with the internal discontinuous conduction mode and the output current will 400mV reference voltage. The MOSFET will be switched off be smaller than the designed value. If the inductance is too when the voltage on CS pin reaches the threshold. The CS large, the Toff may be larger than the maximum off time, the comparator includes a 350ns leading edge blanking time. system will operate in continuous conduction mode and the output current will be higher than the designed value. So it is The peak inductor current is given by: I PK important to choose a proper inductance. 400 ( mA ) R CS Over Voltage Protection The over voltage protection can be programmed by the Where, RCS is the current sense resistor value. The current in LED can be calculated by the equation: I LED ROVP pin resistor. The ROVP pin voltage is 0.5V. When the LED is open circuit, the output voltage I PK 2 increases gradually, and the demagnetization time gets shorter. The demagnetization time at OVP---- Tovp can be Where, IPK is the peak current of the inductor. calculated by the open circuit protection voltage: Inductor Selection Tovp The WS3441A works under inductor current critical conduction mode. When the power MOFET is switched on, L Vcs Rcs Vovp the current in the inductor rises up from zero, the on time of Where， the MOSFET can be calculated by the equation: Vcs is the CS pin turn off threshold (400mV) Vovp is the open circuit protection voltage WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS www.winsemi.com Tel : +86-755-8250 6288 WINSEMI MICROELECTRONICS Fax : +86-755-8250 6299 WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS 5/8 WS3441A ProductDescription And then the Rovp resistor value can be calculated by PCB Layouts the equation: The following rules should be followed in WS3441A Rovp 3.3* Tovp *106 PCB layout: （kohm） Vcc Capacitor The bypass capacitor on VCC pin should be as close as Protection Function possible to the VCC Pin and GND pin. The WS3441A offers rich protection functions to ROVP Pin improve the system reliability, including LED open/short protection, CS resistor short protection, VCC under voltage The ROVP resistor should be as close as possible to the ROVP Pin. protection, thermal regulation. When the LED is open circuit, Ground Path the system will trigger the over voltage protection and stop The power ground path for current sense should be switching. short, and the power ground path should be separated from When the LED short circuit is detected, the system works at low frequency (5kHz), and the CS pin turn off small signal ground path before connecting to the negative node of the bulk capacitor. threshold is reduced to 200mV. So the system power The Area of Power Loop consumption is very low. At some catastrophic fault The area of main current loop should be as small as condition, such as CS resistor shorted or inductor saturated, possible to reduce EMI radiation, such as the inductor, the the internal fast fault detection circuit will be triggered, the power MOSFET, the output diode and the bus capacitor system stops switching immediately. loop. After the system enters into fault condition, the VCC NC pin voltage will decrease until it reaches the UVLO threshold, The NC pin should be connected to GND (pin1). then the system will re-start again. If the fault condition is Drain Pin removed, the system will recover to normal operation. To increase the copper area of DRAIN pin for better thermal dissipation. However too large copper area may Thermal Regulation compromise EMI performance. The WS3441A integrates thermal regulation function. The material of PCB When the system is over temperature, the output current is gradually reduced; the output power and thermal dissipation Avoid choosing the material that is easy to absorb the moisture, just like paper copper-clad laminates. are also reduced. The system temperature is regulated and the system reliability is improved. The thermal regulation temperature is set to 150℃ internally. WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS www.winsemi.com Tel : +86-755-8250 6288 WINSEMI MICROELECTRONICS Fax : +86-755-8250 6299 WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS 6/8 WS3441A ProductDescription Package Information SOP8Package Outline Dimensions B2 A1 A2 0.5* 0.125± 0. 05 球形标记 D D1 B B1 A C4 A3 R2 θ4 C C1 C2 θ2 C3 R1 θ1 θ3 Winsemi Dimensions in Millimeters Symbol Dimensions in Inches Min Max Min Max A 4.70 5.10 0.185 0.201 B 3.70 4.10 0.146 0.161 C 1.30 1.50 0.051 0.059 A1 0.35 0.48 0.014 0.019 A2 1.27TYP 0.05TYP A3 0.345TYP 0.014TYP B1 5.80 B2 6.20 0.228 5.00TYP 0.244 0.197TYP C1 0.55 0.70 0.022 0.028 C2 0.55 0.70 0.022 0.028 C3 0.05 0.225 0.002 0.009 C4 0.203TYP 0.008TYP D 1.05TYP 0.041TYP D1 WINSEMI 0.40 MICROELECTRONICS WINSEMI 0.80 MICROELECTRONICS www.winsemi.com Tel : +86-755-8250 6288 WINSEMI 0.016 MICROELECTRONICS Fax : +86-755-8250 6299 WINSEMI MICROELECTRONICS 0.031 WINSEMI MICROELECTRONICS 7/8 WS3441A ProductDescription NOTE: 1.We strongly recommend customers check carefully on the trademark when buying our product, if there is any question, please don't be hesitate to contact us. 2.Please do not exceed the absolute maximum ratings of the device when circuit designing. 3.Winsemi Microelectronics Co., Ltd reserved the right to make changes in this specification sheet and is subject to change without prior notice. CONTACT: Winsemi Microelectronics Co., Ltd. ADD:Futian District, ShenZhen Tian An Cyber Tech Plaza two East Wing 1002 Post Code : 518040 Tel : +86-755-8250 6288 FAX : +86-755-8250 6299 Web Site : www.winsemi.com WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS www.winsemi.com Tel : +86-755-8250 6288 WINSEMI MICROELECTRONICS Fax : +86-755-8250 6299 WINSEMI MICROELECTRONICS WINSEMI MICROELECTRONICS 8/8