JW1792规格书

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LED照明的电源驱动IC
WT792 Rowlatt ELECTRICAL CHARACTERISTICS TA=25C, unless otherwise stated Item Symbol Condition Min Max Units ∨ p Regulation Voltage VdD 7.4 VoD Start Up threshold VDD st VDD rising 7.1 VV VDD Under Voltage Lockout VDD UVLO VDD falling DD VoD=7. 4V 150 MOS Max on Time TONMAX 30 MOS Min on time TONMIN 0.4 Us MOS Max OFF Time T OFFMAX 400 MOS Min OFF Time ToFFMIN 13 Leading Edge Blanking Time T LEB 400 MOS Max Current IMAX 0.7 MOS BV Voltage VeRDES 550 Mos Rdson dson I(DRAIN)=50mA 14 AVQ℃ Thermal Protection threshold OTPCHIP 145 JW1792 Rev 0.4 JoulWatt Proprietary Information. Patent Protected 3 Unauthorized photocopy and duplication prohibited WT792 Rowlatt PIN DESCRIPTION Pin Name Description TO-92 This pin supplies current to the internal start-up circuitry. This pin must be locally VDD bypassed with a capacitor 2 GND Chip ground DRain The drain of MOSFET BLOCK DIAGRAM VDD DRAIN OTP UVlO VDD charging Control Output Constant Driver SCP current control GND JW1792 Rev 0.4 JoulWatt Proprietary Information. Patent Protected Unauthorized photocopy and duplication prohibited WT792 Rowlatt TYPICAL PERFORMANCE CHARACTERISTICS Waveforms, VIN=90-260Vac, lo=120mA, Vo=60V or 20LEDs(VF=3V)in series Start Up Steady state(output) Short circuit protection VIN=90Vac, lo=120mA, Po=7.2W VIN=220Vac, Io=120mA, Po=7.2W VIN=220Vac 20V/l 100v/divk v WWWW 200m Adl 02A/di 100us/dil Power off Line Regulation SOA VN=220ac,l=120mA,Po=7.2 5v/div 100V/di 10 Line Regulation 0.liv墨 7090110130150170190210230250270 1014节8角0110114015110 JW1792 Rev 0.4 JoulWatt Proprietary Information. Patent Protected 5 Unauthorized photocopy and duplication prohibited WT792 Rowlatt FUNCTIONAL DESCRIPTION The jw1792 is a constant current led driver which applies to non-isolation step -down LED system. JW1792 can achieve excellent line and load regulation, high efficiency and low system cost with few peripheral components LED Start Up When the internal high voltage start-up circuit charges VDD up to the turn-on threshold, the gate driver starts to switch. In the normal working state ETo the current source charges VDD to 7. 4V when the power MOSFET is off. Once the voltage of vdd is lower than 6V, JW1792 stops switching ToN=2lED×L/(VN-VED Where Constant current contro -inductance JW1792 controls the output current from the ILED-output led current information of the current sensing resistor. The ViN-input voltage after rectification and filtering output LED average current can be calculated as:( VLED-output voltage ILED =0.3/Rcs When the power MOSFET turns off, the inductor Where current decreases. The power mosfet turns on Rcs -the sensing resistor connected between again when the inductor current is zero.The chip gnd and the vdd capacitor ground turn-off time of the mosfet can be calculated The inductor current and vdd waveforms are asas follows. ToFF=2lED×L/VLED JW1792 works in quasi- resonant mode. When 7.4V the inductor current decreases to zero resonance VDD 0 takes place between the power inductor, 68V MOSFET output capacitor and stray capacitor JW1792 can detect the zero-current signals of the ILED 一+ inductor, and turn on the MOSFET in the valley hich can reduce the power loss and the EM Inductor Current radiation. If JW1792 cannot get the zero current signals, the turn off time will be changed to Critical Conduction Mode Operation 400uS JW1792 works in the critical conduction mode of Zero current the inductor current When the internal power MOSFET turns on the inductor current increases sMOSFET. from zero linearly. The turn on time of the Turn on MOSFET can be calculated as time JW1792 Rev 0.4 JoulWatt Proprietary Information. Patent Protected Unauthorized photocopy and duplication prohibited WT792 Rowlatt Over Temperature Protection PCB Layout Guidelines № hen jw1792 temperature is higher than145°C, The Vdd pin must be locally bypassed by a LED current reduces, and if it is higher than ceramic capacitor 155C, the output current reduces to zero 2. Make the area of the power loop as small as possible in order to reduce the emi radiation LED Short Protection When the output is shorted, JW1792 cant get the zero current signals. JW1792 stops switching for 400uS until the next pulse JW1792 Rev 0.4 JoulWatt Proprietary Information. Patent Protected Unauthorized photocopy and duplication prohibited WT792 Rowlatt APPLICATION REFERENCE This reference design is suitable for 5-8W non-isolated Step-down LED driver, using JW1792, with high efficiency, excellent line regulation Reference a VIN: 90VAC~264VAC VouT: 40-60V uT: 120mA PF:>0.5 NC BI RWx×HDO6 3mH6*8 ES1J luF/400V 100K/5%1206 176V264 120mA60V 7D47K nH(EF1O g寸 GND C3 luF/16v/0805C 5.1R/1%0805 5.lR/l%0805 JW1792 Rev 0.4 JoulWatt Proprietary Information. Patent Protected 8 Unauthorized photocopy and duplication prohibited WT792 Rowlatt PACKAGE OUTLINE TO-92 UNIT: mm 4.55±0.30 3. 43min 0.46±0.20 1.27TYP oo+寸 2.50+0.40 JW1792 Rev 0.4 JoulWatt Proprietary Information. Patent Protected Unauthorized photocopy and duplication prohibited WT792 Rowlatt SOP8 UNIT. mm 0.42±0.10 -0.51 127→ 1: 27TYP RECOMMENDED LAND FATTERN TOPVEW 5C±0.5 0.15+0.10 一RON SIDE VIEW 于日E DETAIL“A BOTTOM VE JW1792 Rev 0.4 JoulWatt Proprietary Information. Patent Protected 10 Unauthorized Photocopy and Duplication Prohibited

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