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mp24830 4.5v ? 90v, programmable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 1 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. the future of analog ic technology description the mp24830 is a 90v white led driver suitable for either step-down or inverting step-up/down applications. it supports a wide input range with excellent load and line regulation. its programmable current limit provides customized applications with a wide power range. current mode operation provides a fast transient response and eases loop stabilization. fault condition protection includes thermal shutdown, cycle-by-cycle peak-current limiting, open-string protection, and output short-circuit protection. the mp24830 incorporates both dc and pwm dimming onto a single control pin. the separate input reference ground pin allows for direct enable and/or dimming control for a positive-to- negative power conversion. the mp24830 requires a minimal number of readily-available external components. it is available in 14-pin soic and qfn packages. features ? programmable maximum output current ? unique step-up/down operation (buck- boost mode) ? wide 4.5v-to-90v operating input range for step-down applications (buck mode) ? adjustable switching frequency ? analog and pwm dimming ? 0.2v reference voltage ? 10 a shutdown mode ? no minimum led quantity required ? stable with low esr output ceramic capacitors ? cycle-by-cycle over-current protection ? thermal shutdown protection ? open-string protection ? output short-circuit protection ? available in 14-pin soic and qfn packages applications ? general led illumination ? automotive led lighting ? lcd backlight all mps products 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 vin vdd 3 5 6 4 12 7 9 10 11 8 14 1 2 13 dim en ingnd vss rset comp ovp fb dimo sw mp24830 dr u1 cs bst c1 c3 100pf r6 100k c4 4.3nf r3 4.7k c5 1nf d1 r10 c9 22pf r9 499k rcs q1 r7 q2 si4100dy d2 c2 dim en ingnd led- led+
mp24830 ? 4.5v?90v, programable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 2 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. ordering information part number package top marking MP24830HS * soic14 mp24830 mp24830hl ** qfn14 24830 * for tape & reel, add suffix ?z (e.g. MP24830HS?z). * * for tape & reel, add suffix ?z (e.g. mp24830hl?z). package reference dr cs vdd ingnd sw bst vss dimo 1 2 3 4 fb comp ovp 14 13 12 11 10 9 8 dim en rset 5 6 7 top view soic14 qfn14 absolute maxi mum ratings (1) supply voltage v dd ? v ss , v cs ? v ss ............ 90v v sw ? v ss ..............................-0.3v to v in + 0.3v v bst , v dr .............................................. v sw + 6v v en ? v ingnd , v dim ? v ingnd ..............-0.3v to +6v v ingnd ? v ss .....................................-0.3v to 90v other pins ? v ss ..............................-0.3v to +6v continuous power dissipation (t a = +25c) (2) soic14 ...................................................... 1.4w qfn14 ....................................................... 2.6w junction temperature ...............................150c lead temperature ....................................260c storage temperature............... -65c to +150c recommended operating conditions (3) supply voltage v dd ? v ss .................4.5v to 85v operating junction temp. (t j ) -40c to +125c thermal resistance (4) ja jc soic14 ...................................86 ...... 38 ... c/w qfn14 ....................................49 ...... 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 powe r 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 function is not guaranteed outside of the recommended operating conditions. 4) measured on jesd51-7, 4-layer pcb.
mp24830 ? 4.5v?90v, programable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 3 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. electrical characteristices v in = 12v, t a = +25c, all voltages with respect to v ss , unless otherwise noted. parameters symbol condition min typ max units feedback voltage v fb 4.5v ? v in ? 90v 0.188 0.2 0.208 v feedback current i fb v fb = 0.22v -50 50 na under voltage lockout threshold rising v uvloth 3.7 4.1 4.4 v under voltage lockout threshold hysteresis v uvlohy 160 mv operation current (quiescent) i q v en = 2v, v fb = 0.25v 0.8 1.1 ma supply current (quiescent) at en off i off v en =0v 10 23 a gate driver pull-up impedance r pull_up 25 ? gate driver pull-down impedance r pull_down 7 ? gate driver output-high to sw v oh-sw i dr =10ma 5.6 5.8 v gate driver output-low to sw v ol-sw i dr =10ma 0.1 0.3 v dimo source current i dimosc 0.05 a dimo sink current i dimosk 0.05 a dimo output high v dimoh i dr =10ma 4.6 5 v dimo output low v dimol i dr =10ma 0.4 0.5 v oscillator frequency f sw v fb = 0.15v, r set =100k ? 145 215 265 khz min. oscillator frequency f swmin v fb = 0.15v, r set =380k ? 30 50 75 khz max. oscillator frequency f swmax v fb = 0.15v, r set open 245 365 465 khz foldback frequency f swfb v fb = 0v, v ovp =0v, r set =100k ? 30 khz gm of error amplifier gm 80 s error amplifier output current i oamp 40 a current sensing gain g cs 20 high-side current limit threshold v clth 45 mv min. off-time t offmin v fb = 0.19v, r set =100k ? 280 ns min. on-time (5) t on 100 ns en input current i enin v en = 3.3v 3.7 a en off threshold (w/respect to ingnd) v enoffth v en falling 0.4 v en on threshold (w/respect to ingnd) v enonth v en rising 1.4 v min. dim threshold v dimthl v fb = 0.2v 0.6 0.7 0.8 v max. dim threshold v dimthh v fb = 0.2v 1.55 1.75 1.95 v led-short threshold for immediate latch- off 600 mv led short delay for latch-off 450 s led short threshold 300 mv thermal shutdown (5) t tshd 160 c open led ov threshold v ovpth 1.1 1.2 1.3 v open led ov hysteresis v ovphy 50 mv notes: 5) guaranteed by design.
mp24830 ? 4.5v?90v, programable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 4 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. pin functions soic14 name description 1 dr driver output. connect it to the high-side mosfet gate. 2 cs high-side current sense. for over-c urrent protection and current-mode control. 3 vdd supply voltage. operates from a 4.5v-to-85v unregulated input (with respect to vss). needs c1 to prevent large input voltage spikes. 4 ingnd input ground reference. reference for the en/dim signal. 5 dim dimming command input. selects for dc or pwm dimming. when the dim pin voltage (with respect to ingnd) rises from 0.6v to 1.95v, t he led current changes from 0% to 100% of the maximum led current. for pwm dimming, apply a 100hz-to-2khz square wave with an amplitude greater than 2v. for combined analog and pwm dimming, apply a 100hz-to-2khz square wave signal with amplitude from 0.6v to 1.95v. 6 en enable. 7 rset frequency set. connect a resistor to vss to set the switch ing frequency, and a 1nf capacitor to vss to bypass the noise. leaving this pin open for the 350khz defaul t operating frequency. 8 ovp over-voltage protection. use a voltage divider to program ovp threshold. when the ovp pin voltage reaches the 1.2v shutdown threshold, t he switch turns off and recovers when the ovp voltage decreases sufficiently. when the ovp pi n voltage (with respect to vss) falls below 0.4v and the fb pin voltage falls below 0.1v, the chip interprets this as a short circuit and the operating frequency will fold back. program the ov p pin voltage from 0.4v to 1.2v for normal operation. 9 comp error amplifier output. connect a 1nf or larger capacitor on comp and an rc network from fb to comp to improve the stability and to provide soft-start and pwm dimming. 10 fb led current feedback input. a current-sensing resistor between fb and vss provides circuit feedback. the regulation voltage is 0.2v. short-ci rcuit protection triggers if the fb voltage exceeds 300mv for 450s or the fb voltage exceeds 600mv. 11 dimo dim output. provides for accurate pwm diming control following dim logic. connect to the gate of the external dimming mosfet. leave float ing if dimming accuracy is not a concern. 12 vss power return. connect to the circuit?s point of lowest potential, which is typically the anode of the schottky rectifier. ac ts as the voltage reference for the regulated output voltage, and layout requires extra consideration. place this node ou tside of the d1-to-c1 ground path to prevent switching current spikes from inducing voltage noise. connect the exposed pad to this pin. 13 bst bootstrap. connect a capacito r between the sw and bst pins to form a floating supply across the power switch driver. use a 100nf or larger ceramic capacitor to provide sufficient energy to drive the power switch?s gate above the supply voltage. 14 sw switch. connect to the source of the external mosfet
mp24830 ? 4.5v?90v, programable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 5 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. typical performanc e characteristics v en =5v, v in =5v to 85v, i out =0.5a, l=47 h, t a =25c, unless otherwise noted. led string voltage (v) buck-boost i led vs. pwm dimming v in =25v, 3led, f dim =0.2khz buck-boost i led vs. analog dimming v in =20v, 3led, f dim =0.2khz buck i led vs. pwm dimming v in =25v, 3led, f dim =0.2khz input voltage (v) dimming (%) dimming (%) analog dimming voltage (v) efficiency (%) efficiency (%) i led regulation (%) efficiency (%) efficiency (%) i led regulation (%) i out current (ma) i out current (a) i out current (a) v in voltage (v) led string voltage (v) input voltage (v) v in voltage (v) efficiency vs. input voltage buck efficiency vs. input voltage i led =1a efficiency vs. string voltage i led line regulation vs. v in buck efficiency vs. string voltage v in =50v, i led =1a buck i led line regulation vs. v in 2led, i led =1a 70 75 80 85 90 95 100 0 20 40 60 80 100 70 75 80 85 90 95 10 0 5 12 19263340 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 20 30 40 50 60 70 80 90 100 0 100 200 300 400 500 0 20406080100 0 100 200 300 400 500 0 20 40 60 80 100 6led 4led 2led 70 75 80 85 90 95 10 0 020406080100 80 84 88 92 96 10 0 10 15 20 25 30 35 40 -0.6 -0.4 -0.2 0. 0 0. 2 0. 4 0. 6 10 20 30 40 50 60 70 0 200 400 600 800 1000 0. 7 0. 9 1. 1 1. 3 1. 5 1. 7 1. 9 6led v in =20v v in =40v 8led 10led 3led 3led 6led 8led 10led
mp24830 ? 4.5v?90v, programable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 6 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. typical performanc e characteristics (continued) v en =5v, v in =5v to 85v, i out =0.5a, l=47 h, t a =25c, unless otherwise noted. buck iled vs. analog dimming v in =20v, 3led, i out =1a, f dim =0.2khz analog dimming voltage (v) v cs voltage (v) i out current (a) v bst voltage (v) input voltage (v) default f sw (khz) v cs vs. temperature f sw vs. temperature v fb vs. temperature 20 30 40 50 60 70 -50 -10 30 70 110 150 0 100 200 300 400 500 -50 -10 30 70 110 150 170 180 190 200 210 220 230 -50 -10 30 70 110 150 4.5 5.0 5.5 6.0 6.5 7.0 -50 -10 30 70 110 150 500 600 700 800 900 1000 -50 -10 30 70 110 150 40 60 80 100 120 140 -50 -10 30 70 110 150 v bst vs. temperature i q current vs. temperature v in 20v/div. v sw 20v/div. v out 10v/div. i l 1a/div. v in 50v/div. v sw 20v/div. v out 5v/div. i l 1a/div. buck-boost steady state v in = 8v, 3led, i out = 1a buck steady state v in = 14v, 1led, i out = 1a 0 200 400 600 800 1000 0. 7 0. 9 1. 1 1. 3 1. 5 1. 7 1. 9
mp24830 ? 4.5v?90v, programable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 7 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. typical performanc e characteristics (continued) v en =5v, v in =5v to 85v, i out =0.5a, l=47 h, t a =25c, unless otherwise noted. v in 20v/div. v sw 50v/div. v dim 5v/div. i l 1a/div. v in 50v/div. v sw 50v/div. v dim 2v/div. i l 1a/div. v in 20v/div. v sw 20v/div. v dim 5v/div. i l 1a/div. buck-boost pwm dimming v in = 25v, 3led, f dim = 200hz/50% buck-boost analog dimming v in = 25v, 3led, v dim = 0.9a buck pwm dimming v in = 25v, 3led, f dim = 200hz/50% v in 5v/div. v sw 10v/div. v out 10v/div. i l 0.5a/div. v in 50v/div. v sw 50v/div. v en 5v/div. i l 1a/div. v in 50v/div. v sw 50v/div. v en 5v/div. i l 1a/div. buck-boost power ramp up v in = 8v, 3led buck-boost enable power up v in =40v, 3led buck-boost enable power down v in = 40v, 3led v in 20v/div. v sw 20v/div. v ovp 1v/div. i l 1a/div. v in 10v/div. v sw 20v/div. v out 10v/div. i l 1a/div. v in 20v/div. v sw 50v/div. v out 10v/div. i l 1a/div. buck-boost open led protection v in = 25v, 3led, i led = 1a buck-boost short led protection v in = 16v, 3led buck-boost short led to vss v in = 25v, 3led
mp24830 ? 4.5v?90v, programable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 8 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. functional block diagram comp dim dimo cs dr figure 1: functional block diagram
mp24830 ? 4.5v?90v, programable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 9 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. operation the mp24830 is a current-mode regulator. the error amplifier (ea) output voltage is proportional to the peak inductor current. at the beginning of a cycle, m1 is off. the ea output voltage exceeds the current sense amplifier output, and the current comparator?s output is low. the rising edge of the clk signal (its frequency equals the switching frequency) triggers the rs flip-flop. the driver turns on the external mosfet, thus connecting the sw pin and inductor to the input supply. the current-sense amplifier (csa) senses the increasing inductor current. the pwm comparator compares the sum of the ramp generator and the csa output against the output of the error amplifier. when the sum of the csa output and the ramp generator signal exceeds the ea output voltage, the rs flip-flop resets and driver turns off the external mosfet. the external schottky rectifier diode (d1) conducts the inductor current. if the sum of the csa output and the ramp compensation signal does not exceed the ea output for a whole cycle, then the falling edge of the clk resets the flip-flop. the output of the ea integrates the voltage difference between the feedback and the 0.2v reference: a value of 0.2v-v fb increases the ea output voltage. since the ea output voltage is proportional to the peak inductor current, increasing its voltage also increases the current delivered to the output. led open protection if the led is open, there is no voltage on the fb pin. the duty cycle increases until ovp- vss reaches the shutdown threshold set by the external resistor divider. the top switch remains off until the voltage ovp-vss drops below 1.2v. led short protection if the fb voltage exceeds 600mv, the latches off immediately and dimo goes low. if the fb voltage exceeds 300mv for 450s, the ic latches off and dimo is pulled low. the en needs to reset to restart the ic. dimming control the mp24830 allows both dc and pwm dimming on the dim pin. for analog dimming, a voltage range from 0.6v to 1.95v linearly sets the led current from 0% to 100% of the maximum led current. dim voltages exceeding 2v results in the maximum led current. for pwm dimming, use a square signal with an amplitude (v dim ? v ingnd ) that exceeds 1.95v. for good dimming linearity, select a pwm frequency in range of 100hz to 2khz. for a higher dimming frequency or dimming ratio, use the dimo pin to control an external dimming mosfet. for combined analog and pwm dimming, apply a pwm signal with amplitude of 0.6v to 1.95v on the dim pin. output short-circuit protection the mp24830 integrates output short-circuit protection (scp) to foldback the operating frequency and decrease power consumption when the output is shorted to vss. such shorts cause the voltage on the ovp pin to drop below 0.4v, and the fb pin senses no voltage (<0.1v) as no current goes through the wled. in buck-boost applications, when there is a possibility that led+ short-circuits to vss, add a diode from vss to ingnd to protect the ic, as shown in below in figure 2. vdd ovp bst sw dr cs fb dimo rset comp mp24830 vss ingnd en dim off on vin step-up/down white led driver applicatoin dc or pwm input figure 2: buck-boost application with possible led+ short to vss
mp24830 ? 4.5v?90v, programable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 10 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. application information the mp24830 can be used in buck mode and buck-boost mode applications. setting the led current an external resistor r fb sets the maximum led current as per the equation: fb led 0.2v r i ? setting the switching frequency the switching frequency is set by an external resistor, r set , connected from the rset pin to vss the relationship between the switching frequency and the programming resister is as per the following table and shown in figure 3. table 1 r set and f sw relationship f sw (khz) r set (k ? ) 100 200 125 165 210 100 400 50.4 600 30.3 800 19.9 1000 13.2 350 open switching frequency vs. rset 0 200 400 600 800 1000 1200 0 50 100 150 200 250 figure 3: switching frequency vs. r set the mp24380 implements current mode control by sensing the inductor current through a current sensing resistor r cs , as calculated by: cl cs l_pk_max 0.9 v r i ? ? where the v cl is the current limit, v cl =50mv, and i l_pk_max is the maximum peak current in the inductor. calculate r cs using the minimum input voltage, the maximum output voltage and the maximum output current. setting the over-voltage protection the mp24380 detects output over-voltage via the ovp pin. the ovp pin monitors the output voltage through a voltage divider (r ovp1 and r ovp2 ): when the ovp voltage exceeds 1.24v, the ic triggers ovp. select the resistor value ratio using the following equation: out _ ovp ovp1 ovp2 th_ovp v r 1 rv ? ? the ovp trip-point is set between 0.4v and 1.24v. setting the compensation the mp24830 implements current-mode control to regulate the led current feedback through the compensation network on the comp pin. for most applications, use an rcc compensation network to ensure current accuracy and the system stability, as shown in figure 4. its dc gain is: fb zp gm r dcgain _ ea cc ? ? ? where gm is error amplifier?s transconductance of 80a/v. the zero of the compensation network is: z_ea comp z 1 f 2r c ? ?? ? the pole of the compensation network is: p_ea zp comp zp 1 f cc 2r cc ? ? ?? ? ?
mp24830 ? 4.5v?90v, programable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 11 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. figure 4: rcc compensation network on comp pin (1)compensation network for buck-boost application the dc modulator gain of the buck-boost power stage (from the output current to the control voltage on comp pin) is: out in out in out out out cs fb led fb led out in vv vv dcgain _ ps vi*v 20 r ( ) (r r ) rr v v ? ? ? ?? ? ? ? ?? where r cs is the switch current sensing resistor on cs pin, r led is the equivalent dynamic resistance of the led load, as shown in figure 5. i led v led led led led i v r ? ? ? figure 5: led dynamic resistance equivalent the dominant low-frequency pole of the buck- boost power stage is: out out out fb led out in p_ps out out vi*v rr v v f 2v c ? ?? ? ?? the right-half plane (rhp) zero of the buck- boost power stage is: 2 in z_rhp out out in v f 2li (v v) ? ?? ? ? ? step 1: select r comp choose a crossing frequency, f c , below 1/3f z_rhp to derive the compensation network as follow (assume c z >>c p ): c comp fb p _ ps f r gm r dcgain _ ps * f ? ?? that is: c out cs fb led out in comp fb in 2f c 20 r (r r )(v v) r gm r v ?? ? ? ? ? ? ? ?? use the maximum input voltage and minimum output voltage to calculate r comp . step 2: select c z set the zero of the compensation network to cancel the minimum pole of the power stage to get: z p_ps comp 1 c 2f r ? ?? ? choose c z with the maximum input voltage and maximum output voltage. step 3: select c p set the pole of the compensation network to cancel the minimum rhp zero to get: p z_rhp comp 1 c 2f r ? ?? ? choose c p with the minimum input voltage and maximum output voltage.
mp24830 ? 4.5v?90v, programable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 12 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. (2)compensation network for buck application the dc modulator gain of the buck power stage (from the output current to the control voltage) is: cs 1 dcgain _ buck 20 r ? ? the dominant, low frequency pole of the buck power stage is: p_buck fb led esr out 1 f 2(r r r)c ? ?? ? ? ? the zero produced by the esr of the output capacitor is: z _ esr out esr 1 f 2c *r ? ?? where r esr is the esr of the output capacitor. step 1: select r comp choose a crossing frequency, f c , below 1/5f c to derive the compensation network as follows (assume c z >>c p ): c comp buck fb p _ buck f r_ gm r dcgain _ buck * f ? ?? that is: c out cs fb led esr comp _ buck fb 2f c 20 r (r r r ) r gm r ?? ? ? ? ? ? ? ? step 2: select c z set the zero of the compensation network to cancel the minimum pole of the buck power stage to get: z_buck p_buck comp_buck 1 c 2f r ? ?? ? step 3: select c p set the pole of the compensation network to cancel the esr zero. if the esr zero is too high, set this pole at around 3 to 5 times f c : p z _ esr comp _ buck c comp _ buck 11 cmax( , ) 2f r 25fr ? ?? ? ?? ? selecting the inductor select the inductor based on the input voltage, the output voltage, and the led current. select the inductor to make the circuit operate in continuous current mode (ccm). select the inductor current rating to ensure that the inductor does not saturate and with consideration to power consumption based on the dc resistance. (1) selecting the inductor for buck-boost applications for buck-boost applications, select the inductor based on the following equation: in out sw in out l vv l f(vv)i ? ? ? ??? where i l is the peak-to-peak inductor current ripple. design i l to be between 30% and 60% of the average current of the inductor, which is: out l _ avg led in v ii*(1) v ?? select the inductor with a dc current rating that ensurew that the inductor does not saturated at the peak current of: l_pk l_avg l ii 0.5i ? ?? (2) selecting the inductor for buck applications for buck applications, derive the inductance value from the following equation. sw l in out in out f i v ) v v ( v l ? ? ? ? ? ? where i l is the peak-to-peak inductor ripple current. choose the inductor ripple current to around 30% to 60% of the maximum load current. the maximum inductor peak current is calculated as: 2 i i i l load ) max ( l ? ? ? selecting the input capacitor the input capacitor reduces the surge current drawn from the input supply and the switching noise from the device. for best results, use
mp24830 ? 4.5v?90v, programable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 13 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. ceramic capacitors with x7r dielectrics with low esr and small temperature coefficients. select a large-enough capacitor to limit input the voltage ripple, v in , to less than 5% to 10% of the dc value. l_avg out in sw in in out iv c fv(vv) ? ? ?? ? ? selecting the output capacitor the output capacitor limits the output voltage ripple, v out (normally less than 1% to 5% of the dc value), and ensures feedback loop stability. use an output capacitor with impedance at the switching frequency. use ceramic capacitors with low esr characteristics. led out out sw out in out iv c fv(vv) ? ? ?? ? ? pc board layout place the high-current paths (vss, vdd and sw) very close to the device with short, direct, and wide traces. place the input capacitor as close as possible to the vdd and vss pins. place the external feedback resistors next to the fb pin. keep the switch node traces short and away from the feedback network. pay special attention is required to the switching frequency loop layout, which should be as small as possible. for buck applications, the switching frequency loop is composed of the input capacitor, the power mosfet and the schottky diode. place the schottky diode close to the power mosfet and the input capacitor. for buck-boost or boost applications, the switching frequency loop is composed of the input capacitor, the power mosfet, the schottky diode and the output capacitor. make this component loop as small as possible. for most applications, place the output capacitor close to the input capacitor and the power mosfet.
mp24830 ? 4.5v?90v, programable frequency white led driver mp24830 rev. 1.0 www.monolithicpower.com 14 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2013 mps. all rights reserved. package information soic14 0.016(0.41) 0.050(1.27) 0 o -8 o detail "a" 0.010(0.25) 0.020(0.50) x 45 o see detail "a" 0.0075(0.19) 0.0098(0.25) 0.150 (3.80) 0.157 (4.00) pin 1 id 0.050(1.27) bsc 0.013(0.33) 0.020(0.51) seating plane 0.004(0.10) 0.010(0.25) 0.338(8.55) 0.344(8.75) 0.053(1.35) 0.069(1.75) top view front view 0.228 (5.80) 0.244 (6.20) side view 1 7 14 8 recommended land pattern 0.213 (5.40) 0.063 (1.60) 0.050(1.27) 0.024(0.61) note: 1) control dimension is in inches. dimension in bracket is in millimeters. 2) package length do es not include mold flash, protrusions or gate burrs. 3) package width does not include interlead flash or protrusions. 4) lead coplanarity (bottom of leads after forming) shall be 0.004" inches max. 5) drawing conforms to jedec ms-012, variation ab. 6) drawing is not to scale. 0.010(0.25) bsc gauge plane
mp24830 ? 4.5v?90v, programable frequency white led driver notice: the information in this document is subject to change wi thout notice. users should warra nt and guarantee that third party intellectual property rights are not infringed upon w hen integrating mps products into any application. mps will not assume any legal responsibility for any said applications. mp24830 rev. 1.0 www.monolithicpower.com 15 10/30/2013 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. preliminary specifications subject to change ? 2013 mps. all rights reserved. qfn14 side view top view 1 14 8 7 bottom view 2.90 3.10 1.60 1.80 3.90 4.10 3.20 3.40 0.50 bsc 0.18 0.30 0.80 1.00 0.00 0.05 0.20 ref pin 1 id marking 1.70 0.50 0.25 recommended land pattern 2.90 note: 1) all dimensions are in millimeters. 2) exposed paddle size does not include mold flash. 3) lead coplanarity shall be 0.10 millimeter max. 4) jedec reference is mo-229, variation vged-4. 5) drawing is not to scale. pin 1 id see detail a 3.30 0.70 pin 1 id option b r0.20 typ. pin 1 id option a 0.30x45? typ. detail a 0.30 0.50 pin 1 id index area

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