c o p y r igh t @ w i n s em i mic roelectronic s c o . , lt d . , a l l ri g h t r e s er v ed . w/t- s035 -rev.a /0 dec .201 3 ws ws ws ws 3231 3231 3231 3231 1213 features features features features ? 5% led current accuracy ? primary-side sensing and regulation without tl431 and opto-coupler ? no auxiliary winding for sensing and supplying ? high power factor correction ? qr mode ? 600v mos integrated ? ultra low operating current ? led open/short circuit protection ? cs resistor short circuit protection ? vcc over voltage protection & under voltage lockout( uvlo) ? over temperature protection applications applications applications applications ? gu10 led driver ? led spot light ? other led lighting general general general general description description description description WS3231 is a high pf primary-side feedback and regulation controller for led lighting, optimized for flyback converter with the output power less than 30 w. since adopting primary sense and feedback control technology, the secondary sense and feedback circuit is eliminated. and WS3231 does not need the auxiliary winding for sensing the output current and supplying the chip. the low component counts and small system size are realized. since using the high accurate current sense method, WS3231 realizes 5% accuracy of led current along with excellent line and load regulation. WS3231 offers comprehensive protection including cycle-by-cycle current limiting (ocp), led open/short circuit protection, cs resistor short circuit protection, vcc uvlo,ovp and clamp, and over temperature protection. WS3231 is available in so p-8 package. typical typical typical typical application application application application circuit circuit circuit circuit WS3231 high pf psr constant current led driver a c n p n s 1 2 3 4 8 7 6 5 v c c n c c o m p c s g n d d g n d d
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 2 / 7 ws ws ws ws 3231 3231 3231 3231 pin pin pin pin definition definition definition definition and and and and device device device device marking marking marking marking WS3231 is available in sop-8 package: pin pin pin pin function function function function description description description description pin pin pin pin name name name name pin pin pin pin number number number number pin pin pin pin type type type type function function function function description description description description vcc 1 power supply power supply. nc 2 nc f loating comp 3 loop compensation loop compensation pin. connect a rc network across this pin and ground to stabilize the control loop. cs 4 current sense current sense. this pin connects a current sense resistor to gnd to detect the primary current of transformer. d 5/6 drain drain of power mos gnd 7/8 ground ground. block block block block diagram diagram diagram diagram 1 2 3 4 8 7 6 5 v c c n c c o m p c s g n d g n d d d w s 3 2 3 1 s 8 p a x b y m ws 3231 s8p : product code a: die code x: internal code b: area code ym year, month v a lle y to n s d etect l in e compensation r e s e t 9 . 0 v 1 3 .8 v cs*3*tons/t to n s g m 0 . 5 v o c p 0 . 8 v cc&logic control 0 g a te o v p o t p b g &internal power supply to n s v c c c s g n d c o m p 1 5 v u v l o g a te d sampling
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 3 / 7 ws ws ws ws 3231 3231 3231 3231 ordering ordering ordering ordering information information information information package package package package ic ic ic ic marking marking marking marking information information information information purchasing purchasing purchasing purchasing device device device device name name name name so p - 8 , pb-free WS3231 s8p WS3231 s8p recommended recommended recommended recommended operating operating operating operating condition condition condition condition symbol symbol symbol symbol parameter parameter parameter parameter value value value value unit unit unit unit vcc vcc supply voltage 9~14 v t a operating temperature -20~85 pout output power <5 w absolute absolute absolute absolute maximum maximum maximum maximum ratings ratings ratings ratings symbol symbol symbol symbol parameter parameter parameter parameter value value value value unit unit unit unit icc_max vcc pin maximum sink current 5 ma d drain of power mos -0. 3 ~ 60 0 v cs cs pin input voltage -0.3~7 v comp comp pin input voltage -0.3~7 v t j operating junction temperature -40~150 t stg min./max. storage temperature -55~150 note note note note : stresses above those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, functional operation of the device at these or any other conditions beyond those indicated in the recommended operating conditions section are not implied. exposure to absolute maximum-rated conditions for extended periods may affect device reliability.
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 4 / 7 ws ws ws ws 3231 3231 3231 3231 electrical electrical electrical electrical characteristics characteristics characteristics characteristics (t a =25 vcc=14v, if not otherwise noted) symbol symbol symbol symbol parameter parameter parameter parameter test test test test condition condition condition condition min min min min typ typ typ typ max max max max unit unit unit unit supply supply supply supply voltage voltage voltage voltage (vcc) (vcc) (vcc) (vcc) i_vcc_st start up current vcc=uvlo_on-1v 60 100 ua i_op operation current fop=7khz 30 0 4 00 ua uvlo_on turn on threshold voltage vcc rising 12.7 v uvlo_off turn-off threshold voltage vcc falling 1 0 v vcc_clamp vcc clamp voltage icc= 5 ma 15 v current current current current sense sense sense sense section section section section tleb leading edge blanking time 500 ns v th _oc ocp threshold 485 500 515 mv tdelay switch off delay time 200 ns frequency frequency frequency frequency section section section section ton_max max primary on time 24 us toff_max max primary off time 224 us power power power power mos mos mos mos section section section section rds_on on-resistor v gs =10v,i d =0.5a 15 vds_bd b reakdown voltage i d =250 a 600 v over over over over temperature temperature temperature temperature protection protection protection protection tsd thermal shutdown threshold 150 tsd_hys thermal shutdown hysteresis 25
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 5 / 7 ws ws ws ws 3231 3231 3231 3231 f f f f unction unction unction unction description description description description WS3231 is a high pf offline qr psr controller, optimized for low power led driver. WS3231 operates in primary-side sensing and regulation. consequently, opto-coupler and tl431 could be eliminated, thus reduce the cost. startup startup startup startup current current current current startup current of WS3231 is designed to as low as 60ua. the vcc capacitor will be charged through the start-up resistor when the system is powered on. once the vcc voltage reaches the start-up threshold, the WS3231 will start to switch. the WS3231 integrates a 15v zener for vcc clamping. due to the ultra-low operating current, the auxiliary winding is not need to supply the ic. quasi-resonant quasi-resonant quasi-resonant quasi-resonant operation operation operation operation quasi-resonant switching mode is applied in WS3231. when the voltage across drain and source of the primary mosfet is at voltage valley, the mosfet would be turned on, reducing the switching losses and improving emi performance. cc cc cc cc operation operation operation operation WS3231 is designed to produce good cc control characteristic. in dcm mode, the output current io can be represented b y, io=0.5*ips*tons/t where ips is the peak current of the secondary side; tons is the turn on time of secondary side; t is the switching period. ips=ipp*nps=(vcs/rcs)*nps where ipp is the primary peak current; vcs is the voltage on cs resistor; rcs is primary current detection resistor; nps is the turns ratio of primary to secondary of the flyback transformer. the relationship of vcs, to ns and t is controlled to be constant by internal circuit, 3*vcs*tons/t=0.5v. thus, io can be represented b y, io=0.5*(vcs/rcs)*nps*tons/t =(vcs*tons/t)*0.5* nps/rcs =0.083* nps/rcs once the parameters of the transformer and the current sense resistor rcs is determined, so is the output current. and the output current can be set by adjusting the current sense resistor rcs. internal internal internal internal pre-charge pre-charge pre-charge pre-charge design design design design for for for for quick quick quick quick start start start start up up up up after vcc exceeds uvlo_on, vcomp is pre-charged by an internal current source. the pwm block will not start to output pwm signals until vcomp is over 0.45v. such design is meant to reduce the start up time. the voltage pre-charged vcomp in start-up procedure can be programmed b y, vcomp=0.4v-300ua*rcomp where rcomp is the series resistor of comp pin. operation operation operation operation switching switching switching switching frequency frequency frequency frequency the frequency of WS3231 is decided by load condition and qr mode. when the output power decreases, the switching frequency can become rather high. the maximum switching frequency in WS3231 is internally limited to 120khz. current current current current sensing sensing sensing sensing and and and and leading leading leading leading edge edge edge edge blanking blanking blanking blanking cycle-by-cycle current limiting is offered in WS3231. the switch current is detected by a sense resistor into the sense pin. an internal leading edge blanking circuit chops off the sense voltage spike at initial mosfet on state due to snubber diode reverse recovery so that the external rc filtering on sense input is no longer required. the current limit comparator is disabled and thus cannot turn off the ex ternal mosfet during the blanking period. protection protection protection protection controls controls controls controls excellent system stability is achieved by the comprehensive protection of WS3231. including cycle-by-cycle current limiting (ocp), led open/short circuit protection, cs resistor short circuit protection, vcc
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 6 / 7 ws ws ws ws 3231 3231 3231 3231 uvlo,ovp and clamp, over temperature protection, and so on. when the led is open circuit, it will trigger over-voltage protection logic and latch, the system stops switching immediately; when the led short circuit is detected, the system works at low frequency(fop=5khz), so the power loss is low. at some catastrophic fault condition, such as shorted cs resistor or flyback transformer saturation, the internal fast fault detection circuit will trigger and latch, the system stops switching immediately. after the system enters into fault latch condition, the vcc voltage will fall until it reaches uvlo threshold. then the s ystem will re-start again. if the fault condition is removed, the system will recover to normal operation.the thermal shutdown circuitry in the WS3231 senses the die temperature after start up, and the thermal protection threshold is set to 150 with a 25 hysteresis. when the temperature on die of WS3231 rises and reaches the threshold, the power mosfet will be shut down immediately and maintained switch off until the temperature on die falls 25 from thermal protection trigger point .
steady, steady, steady, steady, keep keep keep keep you you you you advance advance advance advance 7 / 7 ws ws ws ws 3231 3231 3231 3231 sop-8 sop-8 sop-8 sop-8 package package package package information information information information symbol symbol symbol symbol winsemi winsemi winsemi winsemi dimensions dimensions dimensions dimensions in in in in millimeters millimeters millimeters millimeters dimensions dimensions dimensions dimensions in in in in inches inches inches inches min min min min max max max max min min min min max max max 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 6.20 0.228 0.244 b2 5.00typ 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 0.40 0.80 0.016 0.031 a b a 1 a 2 a 3 0 . 5 * 0.125 0 05 . b 1 d c 4 c 3 c 1 c c 2 r 2 r 1 1 b 2 3 2 4 d 1
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