preliminary ts19453 ac/dc programmable current wled driver w/pwm dimming control 1/7 version: preliminary so p - 8 general description the ts19453 is a pwm high efficiency programmable c urrent led driver with pwm dimming control ic. it a llows efficient operation of led strings from voltage sou rce ranging up to 400vdc. it includes an internal h igh voltage switching mosfet controlled with fixed off-time of approximately 12s. the led string is driven at constant current, thus providing constant light output and enhanced reliab ility. the output current is internally programmable up to 50m a. the peak current control scheme provides good re gulation of the output current throughout the universal ac l ine voltage range of 85~264vac or dc input voltage of 20~400v features adjust constant output current up to 50ma(typ) universal 85~264vac operation over temperature protection with hysteresis pwm dimming fixed off-time buck converter internal 475v power mosfet typical application circuit application decorating led lighting led lamps with ac or dc operation. ordering information part no. package packing ts19453cs rlg sop-8 2.5kpcs/13 reel note: g denote for halogen free product absolute maximum rating parameter symbol limit unit input voltage range v in to gnd ~ +475 v vdd to gnd v dd to gnd ~ 9 ua pmwd, rsense to gnd ~ v dd +0.3 ua power dissipation @ t a =25oc p d internally limited w operating ambient temperature t opr -40 to +85 oc storage temperature range t stg -65 to +150 o c thermal resistance C junction to ambient r ja 160 o c/w note: stresses beyond those listed under absolute maximu m ratings may cause permanent damage to the device. these are stress rating only, and functiona l operation of the device at these or any other con ditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect d evice reliability. pin definition : 1. rsense 8. drain 2. ground 7. drain 3. pwmd 6. drain 4. vdd 5. ground
preliminary ts19453 ac/dc programmable current wled driver w/pwm dimming control 2/7 version: preliminary electrical specifications (ta = 25 o c, v drain = 50v, unless otherwise noted) function parameter symbol test conditions min typ max units internal regulator internally regulated voltage v dd -- 7.5 -- v drain supply voltage v drain 20 -- 400 v undervoltage lockout threshold uvlo v dd rising 4.8 -- -- v undervoltage lockout hysteresis ? uvlo v dd falling -- 200 -- mv supply current i dd v dd(ext) =8.0v -- -- 500 a output (drain) breakdown voltage v br note 1 475 -- -- v on resistance r dson i drain =50ma -- -- 200 ? mosfet saturation current i sat 100 150 -- ma current sense comparator threshold voltage v th note 1 0.43 -- 0.53 v leading edge blanking delay t blank note 1,2 200 300 400 ns minimum turn on-time t on(min) -- -- 650 ns off-time generator turn on-time t off 8 12 18 s pwmd pwmd input voltage v pwmd high voltage 2.0 -- -- v low voltage -- -- 0.8 pwmd pull down resistance r pwmd vpwmd=5v 100 -- 300 ? note 1: the specification which apply over the full operating ambient temperature range of -40oc preliminary ts19453 ac/dc programmable current wled driver w/pwm dimming control 3/7 version: preliminary function description the ts19453 is a pwm peak current controller for co ntrolling a buck converter topology in continuous c onduction mode (ccm). the output current is of converter that can be programmed by a single external resistor (r sense), for the purpose of driving a string of led, an external enable input (pwmd) is provided that can be utiliz ed for pwm dimming of an led string. when the input voltage of 20~400v appears at the dr ain pin, the internal high-voltage linear regulator seeks to maintain a voltage of 7.5vdc at the vdd pin. until this voltage exceeds the internally programmed unde r-voltage threshold, the output switching mosfet is non-condu ctive. when the threshold is exceeded, the integrat ed high- voltage switch turns on, pulling the drain low, a 2 00mv hysteresis is incorporated with the undervolta ge comparator to prevent oscillation. when the voltage at rsense exceeds 0.47v(typ), the switch turns off and the drain output becomes high impedance, at the same time, a one shot circuit is activated that determines the off-time of the switc h. a blanking delay of 300ns is provided that presen ts false triggering of the current sense comparator due to the leading edge spike caused by circuit parasitic. application information the ts19453 is specifically designed for driving mu lti led strings. it can be operated from either uni versal ac line range of 85~264vac or 20~400vdc, and drives up to t ens of high brightness leds. all leds can be run in series and this device regulates at constant current, yiel ding uniform illumination. selecting l1 and d1 there is a certain trade-off to be considered betwe en optimal sizing of the output inductor l1 and the tolerated output current ripple. the required value of l1 is inversely proportional to the ripple current ? i o in it. l1 = (v o x t off ) / ? i o v o is the forward voltage of the led string. t off is the off-time of the ts19453. the output current in the led string (i o ) is calculated as: i o = (vth / rsense) C ( ? i o / 2) where i th is the current sense comparator threshold, and rse nse is the current sense resistor. the ripple curre nt introduces a peak-to-average error in the output cu rrent setting that needs to be accounted for. due t o constant off- time control technique used in the ts19453, the rip ple current is independent of the input ac or dc li ne voltage variation. therefore, the output current will remai n unaffected by the varying input voltage. adding a filter capacitor across the led string can reduce the output current ripple even further, thu s permitting a reduced value of l1. however, one must keep in mind that the peak-to-average current error is affected by the variation of t off . therefore, the initial output current accuracy mi ght be sacrificed at large ripple current in l1. another important aspect of designing an led driver with ts19453 is related to certain parasitic eleme nts of the circuit, including distributed coil capacitance of l1, junction capacitance and reverse recover of the rectifier diode d1, capacitance of the pcb traces c pcb and output capacitance c drain of the controller itself. these parasitic elements affect the efficiency of the switching con verter and could potentially cause false triggering of the current sense comparator if not properly managed. minimizin g these parasitic is essential for efficient and re liable operation. coil capacitance of inductors is typically provided in the manufacturers data books either directly o r in terms of the self-resonant frequency (srf). srf = 1 / (2 (l * c l ))
preliminary ts19453 ac/dc programmable current wled driver w/pwm dimming control 4/7 version: preliminary application information (continue) l is the inductance value, and c l is the coil capacitance. charging and discharging this capacitance every switching cycle causes high-current spikes in the l ed string. therefore, connecting a small capacitor c o (~100nf) is recommended to bypass these spikes. using an ultra-fast rectifier diode for d1 is recom mended to achieve high efficiency and reduce the ri sk of false triggering of the current sense comparator. using d iodes with shorter reverse recovery time t rr and lower junction capacitance c j achieves better performance. the reverse voltage r ating v r of the diode must be greater than the maximum input voltage of led lamps. the total parasitic capacitance present at the drai n pin of the ts19453 can be calculated as: c p = c drain + c pcb + cl + c j when the switching mosfet turns on, the capacitance c p is discharged into the drain pin of the ic. the di scharge current is limited to about 50ma typically. however , it may become lower at increased junction tempera ture. the duration of the leading edge current spike can be e stimated as: t psike = ((v in x c p ) / (i sat )) + t rr in order to avoid false trigger of the current sens e comparator, c p must be minimized in accordance with the following expression. c p =< (isat * ( t blank(min) - t rr )) / vin(max) when t blank(min) is the minimum blanking time of 200ns, and vin(max ) is the maximum instantaneous input voltage. estimating power loss discharging the parasitic capacitance c p in the the drain output of ts19453 is responsible for the bulk of the switching power loss. it can be estimated using as: p switch = ((c p * v in 2 / 2 ) + (v in * i sat * t rr )) * f s f s is the switching frequency and is the saturated dr ain current of ts19453, the switching loss is the g reatest at the maximum input voltage. disregarding the voltage drop at ts19453 and d1, th e switching frequency is given as f s = (v in - v out ) / (v in * t off ) when the ts19453 is powered from full wave rectifie d ac input, the swithching power loss can be estima ted as: p switch = 1 / (2 * t off ) * ((v ac * c p + 2 * i sat * t rr ) * (v ac - v out ))) when the ts19453 is powered from dc input voltage, conduction power loss can be estimated as: p cond = (d * i out 2 * r on ) + i dd * v in * (1 C d) emi filter as with all off-line converters, selecting an input filter is critical to obtaining good emi. a switch ing side capacitor, albeit of small value, is necessary in order to ens ure low impedance to the high frequency switching c urrents of the converter. as a rule of thumb, this capacitor shoul d be approximately 0.1~0.2f/w of led output power.
preliminary ts19453 ac/dc programmable current wled driver w/pwm dimming control 5/7 version: preliminary typical application circuit typical application circuit for universal 85~264vac led lamps driver (non-isolation) 15pcs led (vled=49.5v), led current 50ma
preliminary ts19453 ac/dc programmable current wled driver w/pwm dimming control 6/7 version: preliminary sop-8 mechanical drawing sop-8 dimension dim millimeters inches min max min max. a 4.80 5.00 0.189 0.196 b 3.80 4.00 0.150 0.157 c 1.35 1.75 0.054 0.068 d 0.35 0.49 0.014 0.019 f 0.40 1.25 0.016 0.049 g 1.27bsc 0.05bsc k 0.10 0.25 0.004 0.009 m 0o 7o 0o 7o p 5.80 6.20 0.229 0.244 r 0.25 0.50 0.010 0.019
preliminary ts19453 ac/dc programmable current wled driver w/pwm dimming control 7/7 version: preliminary notice specifications of the products displayed herein are subject to change without notice. tsc or anyone on its behalf, assumes no responsibility or liability for any erro rs or inaccuracies. information contained herein is intended to provide a product description only. no license, express or implied, to any intellectual property rights is granted by this document. except as provided in tscs terms and co nditions of sale for such products, tsc assumes no liability wh atsoever, and disclaims any express or implied warr anty, relating to sale and/or use of tsc products includi ng liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, cop yright, or other intellectual property right. the products shown herein are not designed for use in medical, life-saving, or life-sustaining applica tions. customers using or selling these products for use i n such applications do so at their own risk and agr ee to fully indemnify tsc for any damages resulting from such i mproper use or sale.
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