ts19452 ac/dc wled driver with internal mosfet universal switch mode 1/7 version: a12 so p - 8 general description the ts19452 is a pwm high efficiency led driver con trol ic. it allows efficient operation of led strin gs from voltage source ranging up to 450vdc. it includes an internal high 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 fixed at 100ma. the pe ak current control scheme provides good regulation of the output current throughout the universal ac line vol tage range of 85~264vac or dc input voltage of 20~4 00v features constant output current at 100ma(typ) universal 85~264vac operation fixed off-time buck converter internal 475v power mosfet low inductance value at 4.7mh (typ) typical application circuit application decorating led lighting led lamps with ac or dc operation. ordering information part no. package packing ts19452cs 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 supply current i dd 400 ua power dissipation @ t a =25oc p d 2500 mw operating ambient temperature t opr -40 to +85 oc storage temperature range t stg -65 to +150 o c junction temperature range t j -40 to +150 o c thermal resistance C junction to ambient r ja 65 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 assignment : 1. drain 8. ground 2. drain 7. ground 3. drain 6. ground 4. vdd 5. ground
ts19452 ac/dc wled driver with internal mosfet universal switch mode 2/7 version: a12 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 -- 450 v undervoltage lockout threshold uvlo v dd rising 5 -- -- v undervoltage lockout hysteresis ? uvlo v dd falling -- 200 -- mv supply current i dd v dd(ext) =8.5v, v drain =40v -- -- 400 a output (drain) breakdown voltage v br note 1 550 -- -- v on resistance r dson i drain =100ma -- -- 100 ? output capacitance c drain v drain =400v -- 1.0 5.0 pf mosfet saturation current i sat -- -- 120 ma current sense comparator threshold current i th note 1 90 -- 110 ma 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 note 1: the specification which apply over the full operating ambient temperature range of -40oc ts19452 ac/dc wled driver with internal mosfet universal switch mode 3/7 version: a12 function description the ts19452 is a pwm peak current controller for co ntrolling a buck converter topology in continuous c onduction mode (ccm). the output current is internally preset at 100ma 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 mosfet t urns on. the input current begins to flow into the drain pin. hysteresis in provided in the under-voltage c omparator to prevent oscillation. when the input current exceeds the internal preset level, a current sense comparator resets an rs flip -flop, and the mosfe turns off, at the same time, a one-shot circu it is activated that determines the duration of the off-state (12s typ.) as soon as this time is over, the flip- flop sets again. the new switching cycle begins. 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 ts19452 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 ts19452. the output current in the led string (i o ) is calculated as: i o = i h C ( ? i o / 2) where i th is the current sense comparator threshold. the rip ple current introduces a peak-to-average error in t he output current setting that needs to be accounted f or. due to constant off-time control technique used in the ts19452, the ripple current is independent of the i nput ac or dc line voltage variation. therefore, th e output current will remain unaffected by the varying input voltage. according a filter capacitor across the led string can reduce the output current ripple even further, thus permitting a reduced value of l1. however, one must keep in mi nd that the peak-to-average current error is affect ed 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 ts19452 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 of the ts19452. 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 cl))
ts19452 ac/dc wled driver with internal mosfet universal switch mode 4/7 version: a12 application information (continue) where 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 ts19452 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 150ma typically. howeve r, it may become lower at increased junction temper ature. the duration of the leading edge current spike can be e stimated as: t psike = ((v in x c p ) / (i sat )) + t r 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.
ts19452 ac/dc wled driver with internal mosfet universal switch mode 5/7 version: a12 electrical characteristics curve figure 1. switch-off transition ch1: v drain , ch3: i drain figure 2. switch-on transition ch1: v drain , ch3: i drain figure 3. lead edge spike ch1: v drain , ch3: i drain
ts19452 ac/dc wled driver with internal mosfet universal switch mode 6/7 version: a12 sop-8 mechanical drawing unit: millimeters marking diagram y = year code m = month code for halogen free product ( o =jan, p =feb, q =mar, r =apl, s =may, t =jun, u =jul, v =aug, w =sep, x =oct, y =nov, z =dec) l = lot code
ts19452 ac/dc wled driver with internal mosfet universal switch mode 7/7 version: a12 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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