unisonic technologies co., ltd USL1601 preliminary cmos ic www.unisonic.com.tw 1 of 6 copyright ? 2014 unisonic technologies co., ltd qw-r125-033.a constant current controller for non-isolated buck led driver ? description the utc USL1601 is a high precision constant current non-isolated buck led driver c ontroller. it can operate under universal ac input, also can operate 12v~600v dc input. the utc USL1601 integrates 600v power mosfet, so it can use very few external components achieve excellent constant current performance. the utc USL1601 uses high precision current sense circuit and patent method for constant curr ent control, to achieve high precision output current an d excellent line regulation. the utc USL1601 operates in inductor current cr itical mode. the led current is constant over wide range of inductance variation and the le d output voltage, so the load regulation is excellent. the utc USL1601 operation current is 200a only, so the auxiliary winding is not needed. it can simplify the system design and reduce the system cost. the utc USL1601 offers rich protection functions, including led short circuit protection, current sense resistor short circuit protection and ov er temperature protection. ? features * inductor current critical mode , no need to compensate the inductance variation * 600v mosfet integrated * 3% led current accuracy * source driver structure, not need the auxiliary winding for v cc * led short circuit protection * up to 93% system efficiency * current sense resistor short circuit protection * over temperature protection ? ordering information ordering number package packing USL1601g-s08-r sop-8 tape reel ? marking
USL1601 preliminary cmos ic unisonic technologies co., ltd 2 of 6 www.unisonic.com.tw qw-r125-033.a ? pin configuration ? pin description pin no. pin name description 1 gnd ground 2 ln line compensation sense input 3 v cc power supply, clamp to 12.5v by internal zener diode 4 source internal hv power mosfet source 5, 6 drain internal hv power mosfet drain 7, 8 cs current sense input, the sense re sistor is connected from cs to ground ? block diagram v cc 8v 7v + - - uvlo restart otp scp constant current & logic control drain source cs ln leb 400mv + - + - gnd current sense line compensation
USL1601 preliminary cmos ic unisonic technologies co., ltd 3 of 6 www.unisonic.com.tw qw-r125-033.a ? absolute maximum rating (t a =25c, unless otherwise specified) parameter symbol ratings unit internal hv mosfet drain voltage v ds -0.3~600 v vcc pin maximum sink current i cc _ ma x 5 ma power dissipation (note 2) p dmax 0.5 w operating junction temperature t j -40~150 c storage temperature range t stg -55~150 c notes: 1. absolute maximum ratings are those values beyond which the device could be permanently damaged. absolute maximum ratings are stress ratings only and functional device oper ation is not implied. 2. the maximum power dissipation decrease if temperature rise, it is decided by t jmax , ja , and environment temperature (t a ). the maximum power dissipation is the lower one between p dmax = (t jmax - t a )/ ja and the number listed in the maximum table. 3. human body mode, 100pf capacitor discharge on 1.5k ? resistor. ? recommended operation conditions parameter symbol ratings unit output led current i led < 135 ma ? thermal data parameter symbol ratings unit junction to ambient ja 150 c/w ? electrical characteristics (note 1, 2) (unless otherwise specified, v cc =12v and t a =25c) parameter symbol test conditions min typ max unit supply voltage section v cc clamping voltage v cc _ clamp 12.5 v v cc clamping current i dd _ clamp 5 ma v cc start up voltage v cc _ st v cc rise 7.6 8.4 9.2 v v cc under voltage latch out hysteresis v uvlo _ hys v cc falling 1 v start up current i st v cc =v cc _ st -0.5v 70 150 a operation current i op 3 ma current sense section current sense voltage threshold v cs_th 290 300 310 mv leading edge blanking time t leb 650 ns turn off delay time t delay 100 ns line compensation section line compensation rate v cs / ? (v ln -v cc ) -40 mv/v over temperature section thermal shut dow temperature t sd 150 c thermal shut down hysteresis t sd_hys 30 c internal hv mosfet switch on resistance r ds _ on v cc =12v 10 ? drain to source voltage v ds 600 v internal driver section minimum demagnetization time t off _ min 4 s maximum demagnetization time t off _ ma x 130 s maximum turn on time t on _ ma x 45 s notes: 1. production testing of the chip is performed at 25c 2. the maximum and minimum parameter s specified are guaranteed by tes t, the typical value are guaranteed by design, characterization and statistical analysis
USL1601 preliminary cmos ic unisonic technologies co., ltd 4 of 6 www.unisonic.com.tw qw-r125-033.a ? function description the utc USL1601 is a constant current cont roller, designed for driving non-isolated buck led power supply. utc USL1601 integrates 600v power mosfet , and it uses patent co nstant current control method and source driver structure, excellent constant cu rrent characteristic is achieved with lo w counts components. low cost and high efficiency of system is realized. start up the v cc will be charged through the startup resistor when t he system is powered on. when the voltage on v cc reaches the startup voltage threshold, t he controller starts to switching. the v cc voltage of utc USL1601 is clamped to 12.5v by internal zener diode. line compensation the utc USL1601 integrates line compensation function. the line voltage is sensed by the voltage difference between ln and v cc pin. and the internal reference voltage of v cs is compensated by a value proportional to the sensed line voltage. the excellent line regulation is achieved. the line compensation coefficient is given by the following equation = v ? cs -4010 -3 (v ln -v cc ) the v cs is the reference voltage of the inte rnal current sense comparator. the v ln is the voltage on ln pin. the v cc is the voltage on v cc pin. constant current control and output current setting the utc USL1601 uses patent constant cu rrent control method, ex cellent constant current is achieved with low counts components. the utc USL1601 senses the peak current in inductor cycle by cycle. the cs pin is connected to the input of internal current comparator, and compared with the internal 300mv reference voltage. the external power mosfet will be turned off when the cs pin voltage reaches the voltage threshold. the comparator has a 650ns leb timer to avoid mis-trigger. the peak current in the inductor is given by: a m ( r 400 = i cs pk the r cs is the resistance of current sense resistor the current in led can be calculated by the following equation: 2 i = i pk led the i pk is the peak current in inductor source driver structure the utc USL1601 uses the patent source driver structure. the typical operat ion current is as low as 3ma, the auxiliary winding is not need. so the syst em design is simple and the cost is low.
USL1601 preliminary cmos ic unisonic technologies co., ltd 5 of 6 www.unisonic.com.tw qw-r125-033.a ? function description(cont.) inductance calculation the utc USL1601 is designed to work in inductor current critical mode, the energy will be stored in the inductor when the mosfet is turned on. the turn on time is given by: led in pk on v - v i l = t the l is the inductance. the i pk is the peak current in inductor. the v in is the input rectified voltage. the v led is the voltage on led. when the power mosfet is turned off, t he inductor current will decrease from t he peak current to zero. the turn off time is given by: led pk off v i l = t the mosfet will be turned on again when it det ects the inductor current goes to zero. the inductance can be calculated by the following equation: in pk led in led v i f ) v - v ( v = l the utc USL1601 internally set the minimu m off time to 4s and maximum off time to 130s. when the inductance is very small, the t off may goes below the minimum off time and the inductor current becomes discontinuous. so the output led current will be smaller than the setting value. if the inductance is too large, the t off may goes beyond the maximum off time and the inductor cu rrent becomes continuous. and the output led current will be larger than the setting value. so it?s very important to select a right inductance. the utc USL1601 also internally set the maximum on time to 40s. when the input voltage is very low or led output voltage is very high, the t on may goes beyond the maximum on time. the power mosfet will be turned off even the inductor current still below the setting value. so the output led curr ent will be smaller than the setting value. protection functions the utc USL1601 has many protection functions, including led shor t circuit protection, current sense resistor short circuit protection and over temper ature protection. all of t he protection functions are designed to auto-recover. the over temperature protection circuitry in the utc USL1601 monitors the die junction temperature after start up. when the temperature rises to 150 c, the power mosfet w ill be shut down immediately and maintains at switch off condition until the temperature on die fa lls 30c below the thermal protection trigger point. pcb layout the following guidelines should be followed in utc USL1601 pcb layout: bypass capacitor the bypass capacitor on v cc pin should be as close as possible to the vcc and gnd pins. ground path the power ground path for current sense should be s hort, and the power ground path should be separated from small signal ground path before the negat ive node of the bus capacitor. the area of power loop the area of main current loop should be as sma ll as possible to reduce emi radiation. and the controller should be placed away from the heat generat or, such as the power diode.
USL1601 preliminary cmos ic unisonic technologies co., ltd 6 of 6 www.unisonic.com.tw qw-r125-033.a ? typical application circuit ac v cc ln source gnd drain drain cs cs utc USL1601 utc assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all utc products described or contained herein. utc products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. the information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.
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