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general description the max1574 charge pump drives up to three white leds with regulated constant current for uniform intensity. by utilizing adaptive 1x/2x charge-pump modes and very-low-dropout current regulators, it achieves 180ma output drive capability and high efficiency over the 1-cell lithium-battery input voltage range. fixed-frequency (1mhz) switching allows for tiny external components, and the regulation scheme is optimized to ensure low emi and low input ripple. the max1574 uses an external resistor to set the full- scale 100% led current. an enable input (en) is used for simple on/off control or can be pulsed repeatedly to set lower led current in multiple steps down to 5%. once the desired brightness is set, the max1574 maintains con- stant led current as long as en is kept high. if en is kept low for more than 2ms, the max1574 enters shutdown. the max1574 is available in a 10-pin 3mm x 3mm tdfn package (0.8mm max height). applications lcd backlighting camera strobes/flashes and movie lights cell phones/smart phones pdas, digital cameras, and camcorders features ? up to 180ma (60ma/led) drive capability ? 83% average efficiency (p led / p batt ) over li+ battery discharge ? 0.5% (typ) led current matching ? adaptive 1x/2x mode switchover ? low input ripple and emi ? 5% to 100% dimming through single-wire serial pulse interface ? low 0.1a shutdown current ? 2.7v to 5.5v supply voltage range ? soft-start limits inrush current ? output overvoltage protection ? thermal-shutdown protection ? 10-pin 3mm x 3mm tdfn package max1574 180ma, 1x/2x, white led charge pump in 3mm x 3mm tdfn ________________________________________________________________ maxim integrated products 1 top view max1574 tdfn 3mm 3mm 10 9 8 7 out gnd led1 led2 6 led3 1234 in en cp cn 4 5 set pin configuration ordering information 1 f 1 f max1574 led3 led2 led1 out set en gnd in 0.22 f cp cn 2.7v to 5.5v on/off and dimming up to 180ma t ypical operating circuit 19-3117; rev 0; 12/03 for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. evaluation kit available part temp range pin- package top mark max1574etb -40? to +85? 10 tdfn 3mm x 3mm abb
max1574 180ma, 1x/2x, white led charge pump in 3mm x 3mm tdfn 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v in = 3.6v, v gnd = 0v, en = in, r set = 13.7k ? , t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25?.) (note 1) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. in, out, en to gnd..............................................-0.3v to +6.0v set, led1, led2, led3, cn to gnd .........-0.3v to (v in + 0.3v) cp to gnd ......................................................................-0.3v to the greater of (v out + 1v) or (v in + 1v) out short circuit to gnd ..........................................continuous continuous power dissipation (t a = +70?) 10-pin tdfn (derate 18.2mw/? above +70?) .......1454mw operating temperature range ...........................-40? to +85? junction temperature ......................................................+150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? parameter conditions min typ max units in operating voltage 2.7 5.5 v undervoltage-lockout threshold v in falling 2.25 2.45 2.60 v undervoltage-lockout hysteresis 40 mv output overvoltage-protection threshold v out rising 5 v 2x mode 2 no-load supply current 10% setting, 1x mode 0.35 ma en = gnd, t a = +25? 0.01 1 shutdown supply current en = gnd, t a = +85? 0.1 ? soft-start time 2ms set bias voltage 0.6 v en = gnd, t a = +25? 0.01 1 set leakage in shutdown en = gnd, t a = +85? 0.1 ? set current range 4 153 ? set-to-led_ current ratio (i led /i set ) 100% setting 393 a/a led current accuracy t a = +25? ?.7 % led-to-led current matching (note 2) -4 ?.5 +4 % maximum led_ sink current r set = 4.12k ? 52 60 ma led_ dropout voltage r set = 4.12k ? (note 3) 80 120 mv 1x to 2x mode transition threshold v led_ falling 120 130 140 mv input-voltage-mode transition hysteresis 150 mv en = gnd, t a = +25? 0.01 2 led leakage in shutdown en = gnd, t a = +85? 0.1 ? maximum out current v in 3.12v, v out = 3.9v 180 ma 1x mode, (v in - v out ) / i out 1.5 2.5 open-loop out resistance 2x mode, (2 x v in - v out ) / i out 915 ? switching frequency 1 mhz out pulldown resistance in shutdown en = gnd 5 k ? en high voltage v in = 2.7v to 5.5v 1.6 v en low voltage v in = 2.7v to 5.5v 0.4 v
max1574 180ma, 1x/2x, white led charge pump in 3mm x 3mm tdfn _______________________________________________________________________________________ 3 note 1: limits are 100% production tested at t a = +25?. limits over the operating temperature range are guaranteed by design. note 2: led current matching is defined as: (i led - i avg ) / i avg note 3: dropout voltage is defined as the led_-to-gnd voltage at which current into led_ drops 10% from the value at v led_ = 0.2v. electrical characteristics (continued) (v in = 3.6v, v gnd = 0v, en = in, r set = 13.7k ? , t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25?.) (note 1) parameter conditions min typ max units en = gnd or 5.5v, t a = +25? 0.01 1 en input current en = gnd or 5.5v, t a = +85? 0.1 ? en low shutdown delay 1.0 2 3.3 ms en t lo (figure 1) 0.5 500 ? en t hi (figure 1) 0.5 ? initial en t hi (figure 1) only required for first en_ pulse 50 ? thermal-shutdown threshold +160 ? thermal-shutdown hysteresis 20 ? t ypical operating characteristics (circuit of figure 2, v in = 3.6v, en = in, driving three white leds, t a = +25?, unless otherwise noted.) efficiency vs. input voltage max1574 toc01 input voltage (v) efficiency (%) 3.9 3.6 3.3 3.0 10 20 30 40 50 60 70 80 90 100 0 2.7 4.2 i led = 2ma i led = 8ma i led = 20ma i led = 40ma v in falling input current vs. input voltage max1574 toc02 input voltage (v) input current (ma) 3.9 3.6 3.3 3.0 50 100 150 200 250 300 0 2.7 4.2 v in falling i led = 40ma i led = 20ma i led = 8ma i led = 2ma input ripple vs. supply voltage max1574 toc03 supply voltage (v) input ripple (mv p-p ) 5.0 4.5 4.0 3.5 3.0 5 10 15 20 25 0 2.5 5.5 60ma/led 20ma/led 8ma/led 2ma/led
max1574 180ma, 1x/2x, white led charge pump in 3mm x 3mm tdfn 4 _______________________________________________________________________________________ t ypical operating characteristics (continued) (circuit of figure 2, v in = 3.6v, en = in, driving three white leds, t a = +25?, unless otherwise noted.) led current matching vs. input supply voltage max1574 toc04 input supply voltage (v) led current matching (%) 5.1 4.7 3.9 4.3 3.5 3.1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1.0 -1.0 2.7 5.5 i led = 8ma led current vs. temperature max1574 toc05 temperature ( c) led current (ma) 60 35 -15 10 7.85 7.90 7.95 8.00 8.05 8.10 8.15 8.20 7.80 -40 85 led current vs. r set max1574 toc06 r set (k ? ) led current (ma) 100 10 10 1000 1 100 1 100% brightness setting operating waveforms (1x) max1574 toc07 v in v out i in 20mv/div ac-coupled 50mv/div ac-coupled 0ma 50ma/div 400ns/div operating waveforms (2x) max1574 toc08 v in v out i in 20mv/div ac-coupled 50mv/div ac-coupled 0ma 400ns/div 50ma/div startup and shutdown max1574 toc09 i in v en v out 100ma/div 0ma 0v 5v/div 2v/div 1ms/div
max1574 180ma, 1x/2x, white led charge pump in 3mm x 3mm tdfn _______________________________________________________________________________________ 5 t ypical operating characteristics (continued) (circuit of figure 2, v in = 3.6v, en = in, driving three white leds, t a = +25?, unless otherwise noted.) dimming response max1574 toc10 i out v en v out 50ma/div 2v/div 2v/div 10ms/div line transient 3.8v to 3.3v to 3.8v max1574 toc11 v out v in i out 1v/div 1v/div 60ma, 20ma/div 100 s/div pin description pin name function 1in supply voltage input. connect a 0.47? to 1? ceramic capacitor from in to gnd. the input voltage range is 2.7v to 5.5v. in is high impedance during shutdown. 2en enable and dimming control. pulsing en low dims the leds in multiple steps. drive low for longer than 2ms (typ) to shut down the ic. from shutdown, drive en high (50? min) to set i led to the maximum current (see the setfunction). pulse en low for 0.5? to 500? to dim the leds (figure 1). 3c pt ransfer-capacitor positive connection. connect a 0.22? capacitor from cp to cn. 4c nt ransfer-capacitor negative connection. connect a 0.22? capacitor from cp to cn. 5 set current-set input. connect a resistor (r set ) from set to gnd to set the maximum led current. i led ( max ) = 393 0.6v / r set . set is internally biased to 0.6v. set is high impedance during shutdown. 6 led3 7 led2 8 led1 led_ cathode connection. current flowing into led_ is based on set description above. in 2x mode, the charge pump regulates the lowest led_ voltage to 0.18v. connect led_ to in for unpopulated leds. led_ is high impedance during shutdown. 9 gnd ground. connect gnd to system ground and as close as possible to the input-bypass capacitor ground. 10 out output. connect a 0.47? to 1? ceramic capacitor from out to gnd, and connect out to the anodes of all the leds. out is pulled to ground through an internal 5k ? resistor in shutdown. ? p exposed paddle. connect the exposed paddle directly to gnd underneath the ic.
max1574 detailed description the max1574 charge pump drives up to three white leds with regulated constant current for uniform inten- sity. by utilizing adaptive 1x/2x charge-pump modes and very-low-dropout current regulators, it achieves 180ma output drive capability and high efficiency over the 1-cell lithium-battery input voltage range. fixed-fre- quency switching of 1mhz allows for tiny external com- ponents, and the regulation scheme is optimized to ensure low emi and low input ripple. 1x to 2x switchover when v in is higher than v out , the max1574 operates in 1x mode and v out is pulled up to v in . the internal cur- rent regulators regulate the led current. as v in drops, v led_ eventually falls below the switchover threshold of 130mv, and the max1574 starts switching in 2x mode. when the input voltage rises above v out by approxi- mately 50mv, the max1574 switches back to 1x mode. soft-start the max1574 includes soft-start circuitry to limit inrush current at turn-on. when starting up, the output capacitor is charged directly from the input with a ramped current source (with no charge-pump action) until the output volt- age approaches the input voltage. once this occurs, the charge pump determines if 1x or 2x mode is required. in the case of 1x mode, the soft-start is terminated and nor- mal operation begins. during the soft-start time, the out- put current is set to 5% of the maximum set by r set . in the case of 2x mode, soft-start operates until the lowest of led1 to led3 reaches regulation. if an overload condi- tion occurs, soft-start repeats every 2.1ms. if the output is shorted to ground, the output current is limited by the max1574 switching technique. setting the output current the led current at full brightness is set by a resistor, r set , as follows: en dimming control when the leds are enabled by driving en high, the max1574 goes through soft-start, bringing the led cur- rent up to i led_ . dimming is then done by pulsing en low (500ns to 500? pulse width). each pulse reduces the led current by 10%, so after one pulse the led cur- rent is 0.9 x i led . the tenth pulse reduces the current by 5%, so the i led_ current reduces from 0.1 x i led_ to 0.05 x i led . the eleventh pulse sets the led current back to i led_ . figure 1 shows a timing diagram for en. if dimming control is not required, en works as a simple on/off control. drive en high to enable the leds, or drive en low for shutdown. shutdown mode when en is held low for 2ms or longer, the max1574 is shut down and put in a low-current mode. out is internally pulled to gnd with 5k ? during shutdown. overvoltage protection if any led fails as an open circuit, the output voltage is limited to about 5v by gating on/off the charge pump. if any led_ is floating or grounded, the max1574 oper- ates in the same overvoltage-protection mode. to avoid overvoltage-protection mode when using fewer than three leds, connect any unused led_ to in (figure 3). thermal shutdown the max1574 includes a thermal-limit circuit that shuts down the ic at approximately +160 ?. the part turns on after the ic cools by approximately 20?. r v i set led . _ = 06 393 180ma, 1x/2x, white led charge pump in 3mm x 3mm tdfn 6 _______________________________________________________________________________________ en i led_ shdn 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 5% 100% 90% shdn 2ms (typ) 1 11 10 9 8 7 6 5 4 3 2 t lo t hi t shdn 500ns 500ns to 500 s 0 t soft-start initial t hi 50 s figure 1. en timing diagram
applications information driving fewer than three leds when driving fewer than three leds, connect any unused led_ directly to in (figure 3). when connected in this manner, the corresponding led driver is disabled. driving camera strobes/flashes the max1574? 180ma output capability makes it suit- able for driving white led camera strobes/flashes. for example, the typical operating circuit drives a 3-led flash module with up to 60ma/led. to ensure 180ma total drive capability at low input voltages, increase c1 to 0.47?. to drive fewer or more leds with regulated total cur- rent up to 180ma or to reduce the number of connect- ing wires, short led1, led2, and led3 together. when connected this way, some led modules have good led-to-led forward-voltage matching, while others may require individual ballast resistors. it is a good idea to keep the ballast resistance as low as practical for reasonable matching because high-ballast resis- tance reduces the output drive capability due to the higher v out requirement. input ripple for led drivers, input ripple is more important than out- put ripple. input ripple depends on the source supply? impedance. adding a lowpass filter to the input further reduces input ripple. alternatively, increasing c in to 2.2? cuts input ripple in half with only a small increase in footprint. the 1x mode always has very low input ripple. component selection use only ceramic capacitors with an x5r, x7r, or better dielectric. see table 1 for a list of recommended parts. pc board layout and routing the max1574 is a high-frequency switched-capacitor voltage regulator. for best circuit performance, use a solid ground plane and place c in , c out , and c1 as close to the max1574 as possible. refer to the max1574 evaluation kit for an example. max1574 180ma, 1x/2x, white led charge pump in 3mm x 3mm tdfn _______________________________________________________________________________________ 7 table 1. recommended components component designation value manufacturer part number description taiyo yuden jmk107bj105ka 1? ?0%, 6.3v x5r ceramic capacitors (0603) c in , c out 1? tdk c1005x5r0j105m 1? ?0%, 6.3v x5r ceramic capacitors (0402) taiyo yuden jmk105bj224kv 0.22? ?0%, 6.3v x5r ceramic capacitor (0402) 0.22? tdk c1005x5r0j224k 0.22? ?0%, 6.3v x5r ceramic capacitor (0402) taiyo yuden jmk105bj474kv 0.47? ?0%, 6.3v x5r ceramic capacitor (0402) c1 0.47? tdk c1005x5r0j474k 0.47? ?0%, 6.3v x5r ceramic capacitor (0402) nichia nscw215t white leds d1, d2, d3 citizen cl-470s white led flash module kamaya r set as required panasonic 1% resistor
max1574 chip information transistor count: 6063 process: bicmos 180ma, 1x/2x, white led charge pump in 3mm x 3mm tdfn 8 _______________________________________________________________________________________ 1 f c1 0.22 f or 0.47 f c in 1 f r set 2.7v to 5.5v selmin 1x/2x regulating charge pump 0.18v error amp2 error amp1 en in cp ovd out 1.25v d1 d2 d3 led1 led2 led3 gnd cn off on set 0.6v control and reference dimming control and enable controlled-current mirror c out max1574 figure 2. functional diagram and typical application circuit 1 f 1 f max1574 led3 led2 led1 out set en gnd in 0.22 f cp cn 2.7v to 5.5v on/off and dimming figure 3. using the max1574 to drive fewer than three leds
max1574 180ma, 1x/2x, white led charge pump in 3mm x 3mm tdfn maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 _____________________ 9 2003 maxim integrated products printed usa is a registered trademark of maxim integrated products. package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation, go to www.maxim-ic.com/packages .) 6, 8, &10l, dfn thin.eps proprietary information title: approval document control no. rev. 2 1 package outline, 6, 8 & 10l, tdfn, exposed pad, 3x3x0.80 mm 21-0137 d l c l c semiconductor dallas a2 a pin 1 index area d e a1 d2 b e2 [(n/2)-1] x e ref. e k 1 n 1 l e l a l pin 1 id c0.35 detail a e number of leads shown are for reference only document control no. approval title: proprietary information rev. 2 2 common dimensions symbol min. max. a 0.70 0.80 d 2.90 3.10 e 2.90 3.10 a1 0.00 0.05 l 0.20 0.40 pkg. code 6 n t633-1 1.500.10 d2 2.300.10 e2 0.95 bsc e mo229 / weea jedec spec 0.400.05 b 1.90 ref [(n/2)-1] x e 1.500.10 mo229 / weec 1.95 ref 0.300.05 0.65 bsc 2.300.10 t833-1 8 package variations 21-0137 0.250.05 2.00 ref mo229 / weed-3 0.50 bsc 1.500.10 2.300.10 10 t1033-1 0.25 min. k a2 0.20 ref. d semiconductor dallas package outline, 6, 8 & 10l, tdfn, exposed pad, 3x3x0.80 mm
english ? ???? ? ??? ? ??? what's new products solutions design appnotes support buy company members max1574 part number table notes: see the max1574 quickview data sheet for further information on this product family or download the max1574 full data sheet (pdf, 224kb). 1. other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales . 2. didn't find what you need? ask our applications engineers. expert assistance in finding parts, usually within one business day. 3. part number suffixes: t or t&r = tape and reel; + = rohs/lead-free; # = rohs/lead-exempt. more: see full data sheet or part naming conventions . 4. * some packages have variations, listed on the drawing. "pkgcode/variation" tells which variation the product uses. 5. part number free sample buy direct package: type pins size drawing code/var * temp rohs/lead-free? materials analysis max1574etb+g104 thin qfn (dual);10 pin;3x3x0.8mm dwg: 21-0137i (pdf) use pkgcode/variation: t1033+1 * -40c to +85c rohs/lead-free: yes materials analysis max1574etb+tg104 thin qfn (dual);10 pin;3x3x0.8mm dwg: 21-0137i (pdf) use pkgcode/variation: t1033+1 * -40c to +85c rohs/lead-free: yes materials analysis max1574etb+ thin qfn (dual);10 pin;3x3x0.8mm dwg: 21-0137i (pdf) use pkgcode/variation: t1033+1 * -40c to +85c rohs/lead-free: yes materials analysis
max1574etb+t thin qfn (dual);10 pin;3x3x0.8mm dwg: 21-0137i (pdf) use pkgcode/variation: t1033+1 * -40c to +85c rohs/lead-free: yes materials analysis max1574etb thin qfn (dual);10 pin;3x3x0.8mm dwg: 21-0137i (pdf) use pkgcode/variation: t1033-1 * -40c to +85c rohs/lead-free: no materials analysis max1574etb-t thin qfn (dual);10 pin;3x3x0.8mm dwg: 21-0137i (pdf) use pkgcode/variation: t1033-1 * -40c to +85c rohs/lead-free: no materials analysis didn't find what you need? contact us: send us an email copyright 2007 by maxim integrated products, dallas semiconductor ? legal notices ? privacy policy

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