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mp2489 step down white led driver with wide 6v ? 60v input voltage mp2489 rev. 1.23 www.monolithicpower.com 1 10/11/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. the future of analog ic technology description the mp2489 is a high efficiency step-down converter designed in continuous current mode for driving the high brightness light emitting diodes (led) from wide input voltage 6v?60v. the mp2489 employs hysteretic control architecture to regulate a high accuracy led current, which is measured through an external high-side current sensing resistor. moreover, this control scheme provides optimized circuit stabilization and very quick response time without the loop compensation. its low 202mv average feedback voltage reduces power loss and improves the converter efficiency. the mp2489 implements pwm and analog dimming together with dim pin. the mp2489 includes thermal overload protection preventing damage in the event of an output overload. the mp2489 is available in small qfn6 (3x 3mm), tsot23-5 and soic8e packages. features ? internal 65v mosfet ? wide 6v to 60v input range ? 1a output current ? high efficiency (>95%) ? hysteresis control ? pwm & analog dimming ? 1000:1 pwm dimming resolution ? thermal shutdown ? inherent open led protection ? short led protection ? available in tsot23-5, qfn6(3x 3mm) and soic8e packages applications ? low voltage halogen replacement ? low voltage general illumination ? automotive/decorative led lighting ? signs/emergency lighting ? led backlighting all mps parts are lead-free and adhere to the rohs directive. for mps green status, please visit mps website under quality assurance. ?mps? and ?the future of analog ic technology? are registered trademarks of monolithi c power systems, inc. typical application v in r sense d1 l1 in c in rs sw en/dim gnd mp2489
mp2489 ? step down wled driver with wide 6v?60v input voltage mp2489 rev. 1.23 www.monolithicpower.com 2 10/11/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. ordering information part number package top marking mp2489dj * tsot23-5 aad mp2489dq qfn6 (3x 3mm) 9y MP2489DN soic8e mp2489 * for tape & reel, add suffix ?z (e.g. mp2489dj?z); for rohs compliant packaging, add suffix ?lf (e.g. mp2489dj?lf?z) package reference sw gnd gnd en/dim in gnd gnd rs 1 2 3 4 8 7 6 5 top view exposed pad on backside connect to gnd tsot23-5 qfn6 (3x 3mm) soic8e absolute maxi mum ratings (1) v in , v sw .........................................-0.3v to +65v v rs ..................................................v in -5v to v in all other pins ...............................-0.3v to +6.3v continuous power dissipation (t a = +25c) (2) tsot23-5 .................................................. 1.3w qfn6 ......................................................... 2.5w soic8e...................................................... 2.6w junction temperature ...............................150 c lead temperature ....................................260 c storage temperature............... -65 c to +150 c recommended operating conditions (3) supply voltage v in ..............................6v to 60v operating junction temp. (t j ). -40c to +125c thermal resistance (4) ja jc tsot23-5 .............................100 ..... 55 ... c/w qfn6 (3mm x 3mm) ..............50 ...... 14 ... c/w soic8e ..................................48 ...... 10 ... c/w notes: 1) exceeding these ratings may damage the device. 2) the maximum allowable power dissipation is a function of the maximum junction temperature t j (max), the junction-to- ambient thermal resistance ja , and the ambient temperature t a . the maximum allowable continuous power dissipation at any ambient temperature is calculated by p d (max)=(t j (max)- t a )/ ja . exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. internal thermal shutdown circuitry protects the device from permanent damage. 3) the device is not guaranteed to function outside of its operation conditions. 4) measured on jesd51-7, 4-layer pcb.
mp2489 ? step down wled driver with wide 6v?60v input voltage mp2489 rev. 1.23 www.monolithicpower.com 3 10/11/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. electrical characteristics v in = 24v, t a = +25 c, unless otherwise noted. parameter symbol condition min typ max units input voltage v in 6 60 v shutdown supply current i sd 108 a quiescent supply current i q no switching 1 ma internal reference voltage i ref 1.275 v feedback reference voltage (with respect to v in ) v in -v rs v en/dim = 1.28v 192 202 212 mv feedback reference voltage hysterisis v fb_hys 30 mv en/dim max dimming voltage v dim_max 2.56 v en/dim mim dimming voltage v dim_min 0.3 v en/dim enable high voltage v en_high v en rising 0.3 v en/dim enable low volatge v en_low v en falling 0.16 v en/dim up-pulling resistor r en 45 k ? recommended pwm dimming frequency f pwm 0.1 2 khz switch on resistance r ds_on 0.5 ? minimum on time t on_min 100 ns minimum off time t off_min 100 ns recommended maximum operating frequency f max 600 khz recommended duty cycle range at f max d 30 70 % start up time t ss external capacitor on dim pin is 4.7nf 0.3 ms
mp2489 ? step down wled driver with wide 6v?60v input voltage mp2489 rev. 1.23 www.monolithicpower.com 4 10/11/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. pin functions tsot23-5 pin# qfn6 pin# soic8 pin# name description 1 1 1 sw the drain of internal mosfet. connecting the common terminal of inductor and anode of schottky to this pin. 2 2, 5 2,3,6,7 gnd ground. 3 3 4 en/dim enable/dimming command input. to use pwm dimming, apply a square wave signal to this pin. to use analog dimming, apply a 0.3v?2.5v dc voltage to this pin. the voltage from 0.3v to 2.5v linearly controls the led current range from 25% to 200%. turn off the output current when pulling this pin below 0.2v. connect a 1nf?10nf capacitor for normal operation (v en/dim =1.28v). 4 4 5 rs led current sense input. connecting the current sensing resistor that programs the led average current to in pin. 5 6 8 in input supply pin. connecting a prop er decoupling capacitor from in pin to gnd.
mp2489 ? step down wled driver with wide 6v?60v input voltage mp2489 rev. 1.23 www.monolithicpower.com 5 10/11/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. typical performanc e characteristics v in =30v, 3 led s in series, i out =550ma, unless otherwise noted. efficiency (%) input voltage (v) efficiency vs. input voltage 70 75 80 85 90 95 100 10 20 30 40 50 60 analog dimming curve 0 0.2 0.4 0.6 0.8 1 1.2 0 0.5 1 1.5 2 2.5 3 analog dim (v) output current (a) iled vs. rset 0 0.2 0.4 0.6 0.8 1 1.2 0.1 0.3 0.5 0.7 0.9 1.1 iled(a) v sw 10v/div. i led 200ma/div. steady state v sw 20v/div. v in 20v/div. i led 500ma/div. vin startup v sw 20v/div. v en 1v/div. en signal 2v/div. i led 500ma/div. ven startup v sw 20v/div. pwm signal 2v/div. i led 500ma/div. pwm dimming f pwm = 200hz, d pwm = 50% v sw 20v/div. v led+ 10v/div. i led 200ma/div. open led protection open leds at working v sw 20v/div. v led- 10v/div. i led 200ma/div. short led protection short leds at working
mp2489 ? step down wled driver with wide 6v?60v input voltage mp2489 rev. 1.23 www.monolithicpower.com 6 10/11/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. function diagram gnd 2 en /dim v in in rs rsense sw l d c in 1.275v reference filter + 0.2v hv regulator 5v enable high side current sense + pwm driver r1 r2 3 54 1 dim figure 1?mp2489 function block diagram
mp2489 ? step down wled driver with wide 6v?60v input voltage mp2489 rev. 1.23 www.monolithicpower.com 7 10/11/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. operation steady state the mp2489 is a hysteretic controlled step down led driver that is easily to be configured in varies applications ranging from 6v?60v input. the converter employs a high side current sensing resistor to detect and regulate the led current. the voltage across the current sensing resistor is kept measured and regulated in 202mv30mv range. the internal 1.275v reference voltage is utilized to provide a 0.2v reference for enabling the part and a 1.275v pulling-up voltage as current reference voltage. when ven>0.2v, the output of the comparator becomes high and the other blocks are enabled. output current is sensed by high-side resistor rsense. when the switch is on, r2 is shorted and output current upper-threshold is fixed by r1. when the switch is off, output current lower- threshold is fixed by r1 and r2. ratio of r1 and r2 determines the current hysteresis. enable control once input voltage is applied, the internal 1.275v reference is connected to en/dim pin through pull up resistor. if en/dim is left open, the ic will automatically start up to the maxim brightness. appling a capacitor on this pin can hereby program a soft start time. if an external voltage range from 1.275v to 1.25v is applied to this pin, the current sensing voltage reference is linearly controlled from 0mv to 202mv. by controlling the en/dim pin voltage the analog dimming can be easily employed. if an external pwm voltage is applied on this pin, the ic will follow the pwm duty to achieve the pwm dimming, the pwm signal amplitude must be about 1.25v. about the flexible external pwm dimming method, please refer to the selecting dimming control mode section. system soft start the voltage on the en/dim pin is the inductor current reference. an external capacitor from the en/dim pin to ground provides a soft-start delay. when v in starts, internal voltage source charges the capacitor from 0v to 1.25v to fulfill soft-start function. dimming control mp2489 provides two dimming methods: pwm dimming and dc analog dimming. to use pwm dimming, apply a square wave to the en/dim pin. to use analog dimming, apply a 0.3v?2.5v dc voltage to this pin. maximum continuous switching current mp2489 max continuous switching current depends on the package with different thermal resistance. the table 1 shows the max continuous current corresponding package for reference. table 1. imax vs. package package tsot23-5 qfn6 soic8e imax(a) 1.00 1.41 1.44
mp2489 ? step down wled driver with wide 6v?60v input voltage mp2489 rev. 1.23 www.monolithicpower.com 8 10/11/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. application information setting the led current the led current is identical and set by the current setting resistor between the in pin and rs pin. r set =202mv/i led for r set =0.36 ? , the led current is set to 550ma selecting the diode the output diode supplies current to the inductor when the internal mosfet is off. to reduce losses due to diode forward voltage and recovery time, use a schottky diode with the mp2489. the diode should be rated for a reverse voltage greater than the input voltage. the average current rating must be greater than the maximum load current expected, and the peak current rating must be greater than the peak inductor current. selecting the input capacitor the input capacitor reduces the surge current drawn from the input supply and the switching noise from the device. a 10f?22f capacitor is enough for most application. the voltage rating should be greater than input voltage. a low esr capacitor should be used for input decoupling. selecting the output capacitor for most applications, output capacitor is not necessary. but if peak to peak ripple led current is required less than 30% of average current, add a capacitor across the leds. proportionally lower ripple can be achieved with higher capacitor value. a value of 2.2f will meet most requirements. selecting soft-start capacitor with the soft-start capacitor, the delay time can be estimated by 0.2ms/nf. in pwm dimming, c<2.2nf is recommended to eliminate its effect on led average current. selecting dimming control mode mp2489 provides two dimming methods: dc analog dimming and pwm dimming. 1. dc analog dimming mode apply a 0.3v?2.5v dc voltage to the en/dim pin. the voltage from 0.3v to 2.5v changes the inductor current reference directly and linearly controls the inductor current range from 25% to 200%. (see figure 2) en/dim vin r6 0 c5 1nf 3 6 5 2 in gnd gnd en/dim mp2489 tp4 figure 2?analog dimming external circuit 2. pwm dimming mode apply a 100hz to 2khz square waveform to the en/dim pin. the average led current is proportional to pwm duty. because this pin is pulled up by 1.25v internal source as inductor current reference, a npn-transistor on/off circuit is recommended to separate pwm signal from the current reference. (see figure 3). the minimum amplitude of the pwm signal is 1.5v. en/dim vin r6 nc r4 10k r7 10k q1 r5 ns c5 1nf 3 6 5 2 in gnd gnd en/dim mp2489 tp4 figure 3?pwm dimming external circuit selecting the inductor lower value of inductance can result in higher switch frequency, which causes larger switch loss. so switch frequency between 200 khz to 600 khz is highly recommended for most application. according to switch frequency, inductor value can be estimated as below: out out in led sw v (1- ) v v l 0.3 i f = for high efficiency, the inductor?s dc resistance should be as small as possible. for 1a application and 40 c temperature rising restriction, figure 4 and 5 can provide a reference for selecting proper value of inductor. pcb size: double layer 5cm x 4.6cm
mp2489 ? step down wled driver with wide 6v?60v input voltage mp2489 rev. 1.23 www.monolithicpower.com 9 10/11/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. figure 4?inductor selection instruction for qfn23-6 figure 5?inductor selection instruction for tsot23-5
mp2489 ? step down wled driver with wide 6v?60v input voltage mp2489 rev. 1.23 www.monolithicpower.com 10 10/11/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. layout consideration careful attention must be paid to the pcb board layout and components placement. r sense should be placed close to the in pin and rs pin in order to minimize set current error. the input loop including input capacitor, schottky diode and internal mosfet should be as short as possible. radiation emi test result figure 6 and 7 represents emi test results for ev2489. 0 5 10 15 20 25 30 35 40 45 50 55 60 30 50 70 100 200 300 frequency(mhz) en 55022 electric field strength 3m qp preview measurement maxpeak figure 6?emi result, vin=12vac, iout=0.24a, 3leds, oats 0 5 10 15 20 25 30 35 40 45 50 55 60 30 50 70 100 200 300 frequency(mhz) en 55022 electric field strength 3m qp preview measurement maxpeak figure 7?emi result, vin=36vac, iout=0.35a, 3leds, oats
mp2489 ? step down wled driver with wide 6v?60v input voltage mp2489 rev. 1.23 www.monolithicpower.com 11 10/11/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. package information tsot23-5 0.30 0.50 seating plane 0.95 bsc 0.84 0.90 1.00 max 0.00 0.10 top view front view side view recommended land pattern 2.80 3.00 1.50 1.70 2.60 3.00 13 4 5 0.09 0.20 note: 1) all dimensions are in millimeters . 2) package length does not include mold flash , protrusion or gate burr. 3) package width does not include interlead flash or protrusion. 4) lead coplanarity (bottom of leads after forming ) shall be 0.10 millimeters max. 5) drawing conforms to jedec mo-193, variation aa. 6) drawing is not to scale . 0.30 0.50 0 o -8 o 0.25 bsc gauge plane 2.60 typ 1.20 typ 0.95 bsc 0.60 typ see detail "a" detail A
mp2489 ? step down wled driver with wide 6v?60v input voltage mp2489 rev. 1.23 www.monolithicpower.com 12 10/11/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. preliminary specifications subject to change ? 2012 mps. all rights reserved. qfn6 (3mm x 3mm) side view top view 1 6 4 3 bottom view 2.90 3.10 1.40 1.60 2.90 3.10 2.20 2.40 0.95 bsc 0.35 0.45 0.80 1.00 0.00 0.05 0.20 ref pin 1 id marking 1.50 0.95 0.40 recommended land pattern 2.90 note: 1) all dimensions are in millimeters . 2) exposed paddle size does not include mold flas h . 3) lead coplanarity shall be 0.10 millimeter max. 4) jedec reference is mo-229, variation veea-2. 5) drawing is not to scale . pin 1 id see detail a 2.30 0.80 pin 1 id option a r0.20 typ. pin 1 id option b r0.20 typ. detail a 0.35 0.55 pin 1 id index area
mp2489 ? step down wled driver with wide 6v?60v input voltage notice: the information in this document is subject to change wi thout notice. users should warrant and guarantee that third party intellectual property rights are not infringed upon when integrating mps products into any application. mps will not assume any legal responsibility for any said applications. mp2489 rev. 1.23 www.monolithicpower.com 13 10/11/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. soic8e

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