c o p y r igh t @ w i n s em i microelectronics c o . , lt d . , a l l ri g h t r e s er v ed . ws9442 product description winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics 0318 features ? critical conduction mode operation ? i nternal 500v powe r mosfet ? gate d rive and no auxiliary winding ? 3% led current accuracy ? efficiency up to 93% ? led short circuit protection ? led open circuit protection ? current sens e resistor short protection ? thermal regulation function applications ? led bulb light s ? led panel light s ? led string s d escription the ws9442 is a high precision buck constant current led driver and is applied to n on-isolated buck led power system with ac input voltage of 85vac-265vac. t he ws9442 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 , s o it doesn t need the auxiliary winding for supplying the chip , thus simplify ing design and reducing cost. the ws9442 adopts intelligent temperature control and thoroughly solves the problem of light flashing at high temperatures. the ws9442p 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 ws9442 is available in dip-7 package . typical application circuit non-isolated buck offline led driver
www.winsemi.com tel : +86-755-8250 6288 fax : +86-755-8250 6299 2 / 9 ws9442 product description winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics pin configuration and marking information t he ws9442 is available in dip-7 package . the top marking is shown as below: pin definition pin no. name description 1 gnd ground 2 rovp over voltage protection setting pin. connect a resistor to gnd 3 nc no connection .should be hanged out. 4 vcc power supply pin 5,6 drain internal hv power mosfet drain 7 cs current sense pin. connect a sense resistor between this pin and gnd pin. block diagram ws9442 d7p product code a product code x internal code bcy internal code for qc y mx d/c
www.winsemi.com tel : +86-755-8250 6288 fax : +86-755-8250 6299 3 / 9 ws9442 product description winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics ordering information package marking part number 7 -pin dip-7 , pb-free ws9442 d7p ws9442 d7p recommended operation conditions part number package input voltage maximum output power ws9442 d7p dip7 175vac-264vac 120v/280ma 160v/220ma 90vac-264vac 80v/300ma absolute maximum ratings s ymbol p arameter range u nit v ds internal hv mosfet drain voltage -0.3~500 v i cc_max vcc pin maximum sink current 10 ma v rovp led open circuit protection voltage regulation -0.3~7 v v cs current sense pin input voltage -0.3~7 v p dmax power dissipation dip7 0.9 w t j maximum operating junction temperature 150 t stg minimum/maximum storage temperature -55~150 n ote stresses beyond those listed under "absolute maximum ratings" may cause permanent damage to the device
www.winsemi.com tel : +86-755-8250 6288 fax : +86-755-8250 6299 4 / 9 ws9442 product description winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics electrical characteristics (unless otherwise specified, vcc= 15 v and ta =25 ) symbol parameter conditions min typ max units supply voltage section v cc _clamp vcc clamp voltage 10 ma 17.8 18.8 19.8 v uvlo_ on chip startup voltage 14 15 16.2 v uvlo_ off vdd under voltage protection 9 9.5 10 v ist startup current v cc = 13 v 150 220 300 ua iop operating current f op=70khz 100 170 250 ua current sense section vcs_th threshold voltage for peak current limit 390 400 410 m v tleb leading edge blanking time for current sense 35 0 ns tdelay switch off delay time 2 00 ns internal time control section toff_max minimum off time 310 us toff_min maximum off time rovp=70k 4.5 us ton_max maximum on time 100 us mosfet section rds_on static drain-source on- state r esistance vgs=15v,ids=0.5a 6.8 bvdss drain-source breakdown voltage vgs=0v,ids=250ua 500 v idss drain-source leakage current vgs=0v,vds=500v 1 0 ua thermal regulation section t reg thermal regulation temperature 150
www.winsemi.com tel : +86-755-8250 6288 fax : +86-755-8250 6299 5 / 9 ws9442 product description winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics function description the ws9442 is a high performance non-isolated b uck converter specially designed for led lighting. the device integrates a 500v power mosfet. with the help of advanced constant current control and g ate d rive technology , the converter achieves excellent constant current performance with very few external components . i t 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. t he ws9442 integrates a 17v zener diode to clamp the vcc voltage. due to the ultra-low operati ng current , the auxiliary winding is not needed to supply the ic. t he typical value of the start - up current is 2 0 0 ua ( the maximum value is 300 u a ). for the application of 176vac 264vac, the start - up resistor can be calculated by the equatio n : _ _ 1.414 176 1.414 820 300 in min st st max v r k i ? ? ? ? ? ? two resistor s in 1206 size smd can be used in series. vcc capacitor selection t he vcc c apacitor is used to bypass noise to ic, so that to assure its sta b le operation, and should be as close as possible to the chip. a 1uf capacitor can be used in vcc. i f selecting mlcc, the material of x7r will be used to satisfy the stability of the capacity under high temperatures. d ue to external damage resulted from small volume and brittle texture of mlcc, the vcc is easy to leakage currents , which will make the ws9442 unable to start. s trict control measures are taken in its layout and productive process . constant current control t he ws9442 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 ws9442 , the cs pin is connected to the current sense comparator, and the voltage on cs pin is compared with the internal 400mv reference voltage . t he 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 : ) ( 400 ma r i cs pk ? where, rcs is the current sense resistor value. the current in led can be calculated by the equation : ) ( 2 ma i i pk led ? where, i pk is t he peak current of the inductor. freewheeling d iode t he diode will b ear the reverse voltage equal to the input voltage when the mosfet is on. a 600v diode was suggested to use . b esides, the operating frequency of f reewheeling d iode is from 20k to 120 khz , such u ltra f ast r ecovery d iode s as es and er whose trr is less than 50ns are good choice. input e lectrolytic c apacitor i nput voltage should be considered in to the capacitor pressure, and the common value is 400v. i n general, the capacity design can be calculated by the following empirical equatio ns : 90vac~264vac: 1w output uses 1uf buck e lectrolytic c apacitor ; 176vac~264vac : 1w output uses 0.5 uf buck electrolytic capacitor . output c apacitor e lectrolytic capacitor is recommended to be use d . i ts stable capac itance can improve the efficiency of power supply , the led ripple current and luminous efficiency . vovp voltage should be considered in output capacitor pressure. inductor selection
www.winsemi.com tel : +86-755-8250 6288 fax : +86-755-8250 6299 6 / 9 ws9442 product description winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics t he ws9442 works in a inductor critical current conduction mode. w hen the power mofet is switched on , the current in the inductor rises up from zero . the on time of the mosfet can be calculated by the equation: led in pk on v v i l t ? ? ? where, l is the inductance value, i pk is the peak current of the inductor, v in is the dc bus voltage after the rectifier bridge , v led is the voltage on the led . after the power mosfet is also switched off and the current in the inductor decreases. when the inductor current reaches zero, the power mosfet is turned on again by ic internal logic. the off time of the mosfet is given by the equation: led pk off v i l t ? ? the inductance can be calculated by the equati on: in pk led in led v i f v v v l ? ? ? ? ? ) ( where, f is the maximum system switching frequency , which is 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 ws9442 is set at 4.5us and 310us , respectively. referring to the equation of toff c alculation, if the inductance is too small, the toff may be smaller than the minimum off time, the system will operate in discontinuous conduction mode and the output current will be smaller than the designed value. i f the inductance is too large, the toff may be larger than the maximum off time, the system will operate in continuous conduction mode and the output current will be higher than the designed value. so it is important to choos e a proper induct ance . thermal regulation t he ws9442 integrates thermal regulation function. when the system is under higher temperature, the output current is gradually reduced; the output power and thermal dissipation are also reduced. the system temperature is regulated and the system reliability is improved. the thermal regulation temperature is set to 150 internally. over voltage protection the o ver voltage protection of the ws9442 can be programmed by the rovp pin resistor. the rovp pin voltage is 0.5v. when the led is open circuit , the period of the output voltage increases gradually , the demagnetization time gets shorter. the d emagnetization time at ovp---- tovp can be calculated by the open circuit protection voltage by the equation: ovp cs cs v r v l tovp ? ? ? where y vcs is the cs pin turn off threshold (0.4v) ; vovp is the open circuit protection voltage . and then the rovp resistor value can be calculated by the equation: 6 10 * * 67 . 7 120 tovp rovp ? ? ? k i i t is suggested that the o pen circuit protection voltage is set at or above 1.5 times m aximum load voltage . protection function t he ws9442 offers rich protection functions to improve the system reliability, including led open/short protection, cs resistor short protection, vcc under voltage protection, thermal regulation. when the led is open circuit, the system will trigger the over voltage protection and stop switching. when the led short circuit is detected, the system works at low frequency and the cs pin turnoff threshold is reduced . s o the system power consumption is very low. at some abnormal fault condition, such as cs resistor short ed or inductor s aturat ion , the internal fast fault detection circuit will be triggered, the system stops switching immediately. after the system enters into fault y condition, the vcc voltage will decrease until it reaches the uvlo threshold , t hen the system will restart again. if the fault condition is removed,
www.winsemi.com tel : +86-755-8250 6288 fax : +86-755-8250 6299 7 / 9 ws9442 product description winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics the system will recover to normal operation. l ine voltage compensation t he ws9442 integrates line voltage compensation function, which makes led current remain unchanged in the range of full voltage with good line regulation and current accuracy . pcb layout the following rules should be followed in ws9442 pcb layout: vcc capacitor: t he vcc c apacitor should be as close as possible to the vcc pin and gnd pin. ground path: the power ground path for current sense resistor should be short, and the power ground path should be separated from small signal ground path before connecting to the negative node of the bulk capacitor. the area of power loop: the area of main current loop should be as small as possible to reduce emi radiation. a nd it should be away from diodes and other heating components . rovp pin: the rovp resistor should be as close as possible to the rovp pin to increase its resistance to prevent from the interference . drain pin: the copper area of drain pin can be increased for better thermal dissipation. a nd it should be away from cs/vcc and rovp pin.
www.winsemi.com tel : +86-755-8250 6288 fax : +86-755-8250 6299 8 / 9 ws9442 product description winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics dip 7 package dimension winsemi symbol dimensions in millimeters dimensions in inches min max min max a 9.00 9.50 0.354 0.374 b 6.10 6.60 0.240 0.260 c 3.0 3.4 0.118 0.134 a1 1.474 1.574 0.058 0.062 a2 0.41 0.53 0.016 0.021 a3 2.44 2.64 0.096 0.104 a4 0.51typ 0.02typ a5 0.99typ 0.04typ c1 6.6 7.30 0.260 0.287 c2 0.50typ 0.02typ c3 3.00 3.40 0.118 0.134 c4 1.47 1.65 0.058 0.065 d 7.62 9.3 0.300 0.366 d1 0.24 0.32 0.009 0.013 d2 7.62typ 0.3typ
www.winsemi.com tel : +86-755-8250 6288 fax : +86-755-8250 6299 9 / 9 ws9442 product description winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics winsemi microelectronics n ote: 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
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