TS19460 ac/dc wled driver with external mosfet universal high brightness 1/7 version: a12 sop - 8 general description the TS19460 is an average current mode control led driver ic. it can be programmed to operate in eithe r a constant frequency or constant off-time mode. and t herefore greatly improves accuracy, line and load r egulation of the led current without any need for loop compen sation or high-side current sensing. the output led current accuracy is at +/-3%, and it is equipped with curre nt limit comparator for hiccup mode output short ci rcuit protection. the TS19460 is includes an 8v~450v linear regulator which allows it to work from a wide range of input voltages without the need for an external low voltage supply . it also includes a pwm dimming input that can acc ept an external control ttl compatible signal. the output current can be programmed by an internal 250mv refe rence, or controlled externally through a 0~1.5v dimming i nput. the TS19460 is ideally suited for buck led dr ivers and is requires only free external components (apart fr om the power stage) to produce a controlled led cur rent making it and ideal solution for low cost led drive rs. features switch mode controller led drivers fast average current controller internal 8v~450v linear regulator constant frequency or constant off-time operation linear and pwm dimming capability requires few external components for operation output short circuit protection with skip mode ordering information part no. package packing TS19460cs rlg sop-8 2.5kpcs / 13 reel note: g denote for halogen free product typical application circuit application dc/dc or ac/dc led driver applications rgb backlighting led driver back lighting of flat panel displays general purpose constant current source signage and decorative led lighting led street lighting absolute maximum rating parameter symbol limit unit input voltage range v in to gnd -0.5 ~ +470 v internal regulated voltage v dd to gnd 12 v cs, ld, pwmd, gate, rt to gnd -0.3 ~ (v dd +0.3) v continuous power dissipation p d 650 mw storage temperature range t a -65 to +150 o c junction temperature range t j -40 to +150 o c thermal resistance C junction to ambient r ja 128 o c/w pin definition : 1. vin 8. rt 2. cs 7. ld 3. gnd 6. vdd 4. gate 5. pwmd
TS19460 ac/dc wled driver with external mosfet universal high brightness 2/7 version: a12 electrical specifications (t a = 25 o c, v in = 12v, v ld =pwm=v dd , unless otherwise noted) function parameter symbol test conditions min typ max units input dc input voltage range v in dc dc input voltage 8.0 -- 450 v shut-down mode supply current i insd pin pwmd to gnd -- 0.5 1.0 ma internal regulator internally regulated voltage v dd v in =8v, i dd(ext) =0 500pf at gate, r t =226k ? 7.25 7.5 7.75 v line regulation of v dd ? v ddline v in =8~450v, i dd(ext) =0 500pf at gate, r t =226k ? 0 -- 1.0 v load regulation of v dd ? v ddload i dd(ext) = 0 ~ 1ma 500pf at gate, r t =226k ? 0 -- 100 mv undervoltage lockout threshold uvlo v dd rising 6.45 6.7 6.95 v undervoltage lockout hysteresis ? uvlo v dd falling -- 500 -- mv maximum input current i in (max) v in =8v 3.5 -- -- ma dimming pwmd input low voltage v enl v in =8v~450v -- -- 0.8 v pwmd input high voltage v enh v in =8v~450v 2.0 -- -- v pwmd pull-down resistance at pwmd r en v pwmd =5v 50 100 150 k ? average current sense logic current sense reference voltage v cs 238 250 262 mv ld to current sense ratio av (ld) t a < +125oc -- 0.18 -- ld input voltage shutdown v ld(off) v ld falling -- 150 -- mv ld input voltage enable ? v ld(off) v ld rising -- 200 -- mv current sense blanking interval t blan k 150 -- 280 ns minimum on-time t on(min) v cs = v cs + 30mv -- -- 1 us off time t off r t =1m ? 32 -- 48 us r t =226k ? 8 -- 12 max. steady-state duty cycle d max 75 -- -- % short circuit protection hiccup threshold voltage v c s 410 -- 470 mv current limit delay cs to gate t delay v cs = v cs + 30mv -- -- 150 ns short circuit hiccup time t hiccup 330 -- 460 us minimum on-time (short circuit) t on(min) v cs = vdd -- -- 430 ns gate driver gate sourcing current i source v gate =0v, v dd =7.5v 165 -- -- ma gate sinking current i sink v gate =v dd , v dd =7.5v 165 -- -- ma gate output rise time t rise c gate =500pf, v dd =7.5v -- 30 50 ns gate output fall time t fall c gate =500pf, v dd =7.5v -- 30 50 ns note 1 : limited by package power dissipation, whichever i s lower
TS19460 ac/dc wled driver with external mosfet universal high brightness 3/7 version: a12 block diagram pin description pin function description 1 vin this pin is the input of 8v~450v linear regul ator 2 cs this pin is the current sense pin used to sense the mosfet current by means of an external sense resistor. 3 gnd ground return for all internal circuitry. this pin must be electrically connected to the ground of the power train. 4 gate this pin is the output gate driver for an ex ternal n-ch power mosfet 5 pwmd this is the pwm dimming input of the ic. when this pin is pulled to gnd, the gate driver is turned off. when the pin is pulled high, the gate d river operates normally. 6 vdd this is the power supply pin for all internal circu its. it must be bypassed with a low esr capacitor to gnd ( 0.1f) 7 ld this pin is the linear dimming input and sets the c urrent sense threshold as long as the voltage at the pin is less than 1.5v, the gate outp ut is disable when ld voltage <150mv(typ.) and recovery when ld voltage >200mv (t yp.) 8 rt a resistor is connected between rt and gnd to progr am the gate off-time within the range of 30kohm
TS19460 ac/dc wled driver with external mosfet universal high brightness 4/7 version: a12 application information the TS19460 is optimized to drive buck led drivers using average current mode control. this method of control enables fairly accurate led current control without the need for high side current sensing or the desi gn of any closed loop controllers. the ic uses very few exter nal components and enables both linear and pwm dimm ing of the led current. a resistor connected to the rt pin programs the fre quency of operation (or the off-time). constant fre quency of average current mode control is used for stability and to improve the led current regulation over a w ide range of input voltages. the current through the switching mosfet source is averaged and used to give constant-current feedback . this current is detected from a sense resistor at the cs pin, the feedback operates is a fast open-loop mod e, there are no compensation is required, the output current is programmed as i led = 0.25v / r cs when the voltage at the ld input >1.5v, otherwise i led = ( v ld * 0.181 ) / r cs when application to design the inductor witching ri pple current in it is 40% of average peak to peak, full load current, the inductance can be calculated as follow : l out = ( v out(max) * t off ) / ( 0.4 * i out ) the duty cycle range of current control feedback is limited to <0.75%, when the led string voltage is greater than 75% of input voltage, the led current will be reduc ed. when output led voltage is below v out(min) = v in * d (min) , where d (min) = 1us / (t off + 1us) , it also occurred the loss of regulation of led current. this conditi on will cause an increase in led current and can be possible to trip the short circuit protection comparator when t he voltage at cs exceeds 0.44v, the gate off time ( t hiccup = 400us) is generated to prevent stair casing of indu ctor current. the leading edge blanking delay is pr ovide at cs to prevent false triggering of current feedback and sh ort circuit protection, both of output open or shor t condition is required to recycle the v dd to restore to operate in normally. input voltage regulator the TS19460 can be powered directly from its vin pi n and can work from 8.0v~450vdc at its vin pin. whe n a voltage is applied at the vin pin, the TS19460 main tains a constant 7.5v at the vdd pin. this voltage is used to power the ic and any external resistor dividers nee ded to control the ic. the vdd pin must be bypassed by a low esr capacitor to provide a low impedance path for t he high frequency current of the output gate driver . the TS19460 can be also operated by supplying a voltage at the vdd pin greater than the internally regulat ed voltage. please note that this external voltage at the vdd p in should not exceed 12v. although the vin pin of the TS19460 is rated up to 450v, the actual maximum voltage that can be applie d is limited by the power dissipation in the ic. for example, if an sop-8 (junction to ambient thermal resistance r ja = 128c/ w) TS19460 draws about i in = 2.0ma from the vin pin, and has a maximum allowab le temperature rise of the junction temperature limited to about the maximum v oltage at the vin pin would be: v in(max) = ( t j(max) C t a ) / ( r ja * i in ) = 390v in these cases, to operate the TS19460 from higher input voltages, a zener diode can be added in serie s with the vin pin to divert some of the power loss from the t s19460 to the zener diode. in the above example, us ing a 100v zener diode will allow the circuit to easily work u p to 490v.
TS19460 ac/dc wled driver with external mosfet universal high brightness 5/7 version: a12 application information (continue) the input current drawn from the vin pin is a sum o f the 1.0ma current drawn by the internal circuit a nd the current drawn by the gate driver (which in turn depends on the switching frequency and the gate charge of the external i in 1ma + q g x f s in the above equation, f s is the switching frequency and q g is the gate charge of the external mosfet (which can be obtained from the datasheet of the mosfet). oscillator the oscillator in the TS19460 is controlled by a si ngle resistor connected at the rt pin. the equation governing the oscillator time period t osc is given by: t off(us) = ( rt (k ? ) / 25 ) + 0.3 linear dimming the linear dimming pin is used to control the led c urrent, when voltage at ld is fall below 1.5v, the internal reference voltage (250mv) to the constant current f eedback become over ridden by vld * 0.181, and the current in the inductor remain continuous, the led current is given by i led = ( v ld * 0.181 ) / r cs , the gate output is disable when ld voltage <150mv(typ.) and recovery when ld v oltage >200mv (typ.) the linear dimming input could also be used for mix ed-mode dimming to expand the dimming ratio, in thi s kind of application condition, the pulse-width modulated si gnal of a measured amplitude below 1.5v should be a pplied at ld. pwm dimming pwm dimming can be achieved by driving the pwmd pin with a square wave signal. the rising and falling edges are limited by current slew rate in inductor, the f irst switching cycle is terminated upon reaching th e level (250mv) at cs, the circuit is further reaching its steady s tate within 3~5 switching cycle regardless of the s witching frequency.
TS19460 ac/dc wled driver with external mosfet universal high brightness 6/7 version: a12 sop-8 mechanical drawing marking diagram y = year code m = month code for haloge n 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 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
TS19460 ac/dc wled driver with external mosfet universal high brightness 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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