View MAX1577YETAT_8447563.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

general description the max1577y/max1577z charge pumps drive whiteleds, including camera strobes, with regulated current up to 1.2a (guaranteed to 800ma). the very low open- loop output resistance allows high flash brightness, even from a low battery input voltage. the adaptive 1x/2x regulating charge-pump operation provides high efficiency (up to 92%) while in movie mode or back- lighting. fast (1mhz) switching allows the use of tiny external components. the max1577y/max1577z use an external resistor to set the full-scale led current. two enable inputs (en1 and en2) provide simple on/off control and led current of 20%, 33%, or 100% full scale. if there is less than 24mv across the external resistor, the output voltage is regulated. the max1577z has fixed 5.1v output-volt- age regulation, while the max1577y has logic-con- trolled output voltage of 3.4v, 4.6v, or 5.1v for backlighting, keyboard, and rgb applications. the max1577y/max1577z are available in an 8-pin, 3mm x 3mm tdfn package (0.8mm max height). applications white led flashes, strobes, and movie lightslcd backlighting camera phones, cell phones, and smart phones pdas, digital cameras, and camcorders features ? up to 1.2a output drive capability (800maguaranteed) ? up to 92% p led / p batt efficiency for movie mode ? flexible brightness control two-bit logic for 100%, 33%, 20%, and offpwm for 20% to 100% ? 3% current regulation over line andtemperature ? current or voltage regulation for flash andbacklighting (max1577y) ? current regulation for flash (max1577z) ? low ripple and emi ? 2.7v to 5.5v supply voltage range ? soft-start limits inrush current ? output-voltage regulation mode ? thermal-shutdown protection ? 8-pin 3mm x 3mm tdfn package max1577y/max1577z 1.2a white led regulating charge pump for camera flashes and movie lights ________________________________________________________________ maxim integrated products 1 max1577y max1577z 8 out 7 cs 6 in 5 gnd 3 cn 2 cp 4 en2 1 en1 tdfn top view pin configuration ordering information max1577z 1 f or 2.2 f 5.3v ovp v out - (300mv or 100mv or 60mv) up to 1.2a 2.7v to 5.5v 4.7 f 10 f 100%, 33%, 20%, and shutdown cp cn en1 in out cs gnd en2 t ypical operating circuit 19-3461; rev 0; 11/04 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 max1577y eta -40? to +85? 8 tdfn(t833-2) amg max1577z eta -40? to +85? 8 tdfn(t833-2) amq downloaded from: http:///
max1577y/max1577z 1.2a white led regulating charge pump for camera flashes and movie lights 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics(v in = 3.6v, circuit of figure 2, en1 = en2 = in, r cs = 60 ? , c in = 4.7?, c1 = 2.2?, c out = 10?, 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 ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. in, out, en1, en2 to gnd ...................................-0.3v to +6.0v out to gnd during shutdown....................-0.3v to (v in + 0.3v) out to cs .............................................................-0.6v to +0.6v cs to gnd................................................-0.3v to (v out + 0.3v) 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?) 8-pin tdfn (derate 18.2mw/? above +70?) ..........1455mw 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 rising 2.3 2.45 2.6 v undervoltage-lockout hysteresis 35 mv 1mhz switching, no load 5 supply current 1x ldo mode, no switching 0.225 0.3 ma t a = +25 c 0.01 1 shutdown supply current en1 = en2 = gnd t a = +85 c 0.2 ? soft-start time 0.5 ms out overvoltage protection 5.3 v max1577z, t a = +25 c, i out = 100ma en1 or en2 = in 4.95 5.10 5.25 en1 = gnd, en2 = in 3.17 3.40 3.60 en1 = in, en2 = gnd 4.40 4.60 4.80 out voltage regulation mode max1577y, t a = +25 c, i out = 100ma en1 = en2 = in 4.95 5.10 5.25 v cs voltage-mode threshold(v out - v cs ) 24 mv en1 = gnd, en2 = in 60 en1 = in, en2 = gnd 100 cs regulation voltage(v out - v cs ) en1 = en2 = in 300 mv t a = +25 c- 2 ?.5 +2 cs threshold accuracy v in = 2.7v to 5.5v, t a = -40 c to +85 c- 3 + 3 % v in = 3.1v 600 900 maximum out current v led = 4.1v, en1 = en2 = in v in = 3.4v 800 1200 ma 1x ldo mode 0.6 open-loop out resistance 2x mode, v in = 3.4v 2 3 ? out internal pulldown inshutdown en1 = en2 = gnd 5 k ? switching frequency 0.80 1.0 1.25 mhz downloaded from: http:///
max1577y/max1577z 1.2a white led regulating charge pump for camera flashes and movie lights _______________________________________________________________________________________ 3 led current vs. supply voltage max1577 toc01 supply voltage (v) led current (ma) 5.1 4.7 4.3 3.9 3.5 3.1 200 400 600 800 1000 1200 0 2.7 5.5 r cs = 0.27 ? 1100ma at 3.78v f 370ma at 3.33v f 220ma at 3.15v f efficiency vs. supply voltage max1577 toc02 supply voltage (v) efficiency (%) 5.1 4.7 3.9 4.3 3.5 3.1 10 20 30 40 50 60 70 80 90 100 0 2.7 5.5 r cs = 0.27 ? 220ma at 3.15v f 370ma at 3.33v f 1100ma at 3.78v f battery current vs. supply voltage max1577 toc03 supply voltage (v) battery current (ma) 5.1 4.7 3.9 4.3 3.5 3.1 500 1000 1500 2000 2500 0 2.7 5.5 r cs = 0.27 ? 220ma at 3.15v f 370ma at 3.33v f 1100ma at 3.78v f led current vs. supply voltage max1577 toc04 supply voltage (v) led current (ma) 5.1 4.7 4.3 3.9 3.5 3.1 100 200 300 400 500 900600 700 800 0 2.7 5.5 r cs = 0.39 ? 770ma at 3.66v f 250ma at 3.21v f 150ma at 3.06v f efficiency vs. supply voltage max1577 toc05 supply voltage (v) efficiency (%) 5.1 4.7 3.9 4.3 3.5 3.1 10 20 30 40 50 60 70 80 90 100 0 2.7 5.5 r cs = 0.39 ? 770ma at 3.66v f 250ma at 3.21v f 150ma at 3.06v f battery current vs. supply voltage max1577 toc06 supply voltage (v) battery current (ma) 5.1 4.7 3.9 4.3 3.5 3.1 400200 600 800 1000 18001600 1200 1400 0 2.7 5.5 r cs = 0.39 ? 770ma at 3.66v f 250ma at 3.21v f 150ma at 3.06v f t ypical operating characteristics (v in = 3.6v, circuit of figure 2, r cs = 0.27 ? , luxeon lxcl-pwf1 led, t a = +25 c, unless otherwise noted.) electrical characteristics (continued)(v in = 3.6v, circuit of figure 2, en1 = en2 = in, r cs = 60 ? , c in = 4.7?, c1 = 2.2?, c out = 10?, t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25?.) (note 1) note 1: limits are 100% production tested at t a = +25 c. limits over the operating temperature range are guaranteed by design. parameter conditions min typ max units v in = 4.2v to 5.5v 1.6 en_ logic-high voltage v in = 2.7v to 4.2v 1.4 v en_ logic-low voltage v in = 2.7v to 5.5v 0.4 v t a = +25? 0.02 1 logic input current v en _ = 0v or 5.5v t a = +85? 0.02 ? thermal-shutdown threshold t j rising +160 c thermal-shutdown hysteresis 20 c downloaded from: http:///
max1577y/max1577z 1.2a white led regulating charge pump for camera flashes and movie lights 4 _______________________________________________________________________________________ led current vs. temperature max1577 toc07 temperature ( c) led current (ma) 60 35 10 -15 205 210 215 220 225200 -40 85 r cs = 0.27 ? en1 lowen2 high led current vs. r cs max1577 toc08 r cs ( ? ) led current (a) 0.8 0.6 0.4 0.2 0.4 0.6 0.8 1.0 1.2 0 0.2 1.0 en1 and en2 high en1 high, en2 low en1 low, en2 high typical operating waveforms in 1x mode max1577 toc09 400ns/div v in v out v cs 50mv/div(ac-coupled) 50mv/div (ac-coupled) 50mv/div (ac-coupled) typical operating waveforms in 2x mode max1577 toc10 400ns/div v in v out v cs 50mv/div(ac-coupled) 50mv/div (ac-coupled) 50mv/div (ac-coupled) startup and shutdown response max1577 toc11 400 s/div v en1, v en2 v led i led 2v/div2v/div 0v 0ma 500ma/div led current vs. pwm duty cycle max1577 toc12 duty cycle (%) led current (ma) 80 60 40 20 200 400 600 800 1000 1200 0 01 0 0 r cs = 0.27 ? en1 pwmen2 high efficiency vs. supply voltage with pwm dimming max1577 toc13 supply voltage (v) efficiency (%) 5.1 4.7 4.3 3.9 3.5 3.1 3020 10 40 50 60 70 80 0 2.7 5.5 25% 50% 75% r cs = 0.27 ? en1 pwmen2 high dimming response max1577 toc14 100 s/div v en1 v led i led 2v/div2v/div 0v 0ma 500ma/div t ypical operating characteristics (continued) (v in = 3.6v, circuit of figure 2, r cs = 0.27 ? , luxeon lxcl-pwf1 led, t a = +25 c, unless otherwise noted.) downloaded from: http:///
max1577y/max1577z 1.2a white led regulating charge pump for camera flashes and movie lights _______________________________________________________________________________________ 5 pin description pin name function 1 en1 control logic input (see table 1) 2c p transfer capacitor positive connection. connect a 1? capacitor (or 2.2? for i out > 600ma) from cp to cn. 3c n transfer capacitor negative connection. connect a 1? capacitor (or 2.2? for i out > 600ma) from cp to cn. 4 en2 control logic input (see table 1) 5 gnd ground 6i n input supply voltage. connect in to a battery or supply voltage from 2.7v to 5.5v. connect a 4.7?ceramic capacitor from in to gnd. 7c s current-sense input. connect a current-sense resistor from out to cs to set the output current.connect the anodes of the leds to cs and the cathodes to gnd. 8 out output. connect a 10? ceramic capacitor from out to gnd. in shutdown, out is pulled to gndwith an internal 5k ? resistor. ? p exposed pad. connect the exposed pad to gnd directly under the ic. table 1. enable, dimming, voltage mode, and overvoltage protection voltage mode ovp en1 en2 dimming level cs threshold (v out - v cs ) max1577z max1577y max1577z max1577y 00 shutdown 01 20% current 60mv 5.10v 3.40v 5.30v 5.15v 10 33% current 100mv 5.10v 4.60v 5.30v 5.17v 11 100% current 300mv 5.10v 5.10v 5.30v 5.30v note: a ??indicates en_ is logic low or connected to gnd. a ??indicates en_ is logic high or connected to in. downloaded from: http:///
max1577y/max1577z 1.2a white led regulating charge pump for camera flashes and movie lights 6 _______________________________________________________________________________________ max1577y max1577z max1577y only imode/vmode mux csvmode error amp en1en2 v out - v cs r cs cs d1 c out 10 f out c in 4.7 f ingnd 1.25v 24mv control ldo/charge pump c1 1 f* cn cp 2.7v to 5.5v *2.2 f for more than 600ma output. figure 1. functional diagram downloaded from: http:///
max1577y/max1577z 1.2a white led regulating charge pump for camera flashes and movie lights _______________________________________________________________________________________ 7 max1577z c1 2.2 f* 5.3v ovp r cs v out - (300mv or 100mv or 60mv) up to 1.2a 2.7v to 5.5v c in 4.7 f c out 10 f 100%, 33%, 20%, and shutdown cp cn en1 in out cs gnd en2 *1 f for less than 600ma output. or max1577y c1 1 f 5.1v, 4.6v, or 3.4v 2.7v to 5.5v c in 4.7 f c out 10 f 5.1v, 4.6v, 3.4v and shutdown cp cn en1 in out cs gnd en2 figure 2. current regulation with the max1577zfigure 3. voltage regulation with the max1577y downloaded from: http:///
max1577y/max1577z 1.2a white led regulating charge pump for camera flashes and movie lights 8 _______________________________________________________________________________________ detailed description 1x ldo to 2x mode switchover when v in is greater than v out , the max1577y/ max1577z are in 1x ldo mode and regulate the cur- rent through r cs . as v in decreases and the ldo approaches dropout, the 2x charge pump starts boostingthe output to maintain the regulation current. when v in rises enough above v out to maintain ldo regulation, the charge pump stops and the max1577y/max1577zswitch back to the more efficient 1x ldo mode. soft-start the max1577y/max1577z include soft-start circuitry tolimit inrush current at turn-on. when starting up with an output voltage that is not near the input voltage, the out- put capacitor is charged directly from the input with a ramped current source (with no charge-pump action) until the output voltage approaches the input voltage. if current-mode or voltage-mode regulation is met, soft- start is terminated and normal operation begins in 1x mode. otherwise, after 500?, the 2x charge-pump soft- start operates until the voltage across the sense resistor reaches the current regulation threshold, the output volt- age is in regulation, or 500? has elapsed, whichever occurs first. if the output is shorted to ground, soft-start is repeated until the output exceeds 2.3v. dimming and shutdown the max1577y/max1577z use two inputs (en1 anden2) to select between three brightness levels and low- power shutdown mode (see table 1). by regulating the voltage across the current-sense resistor (v out - v cs ) to one of three levels, the max1577y/max1577z control theoutput current, thus providing the three-level dimming. in shutdown mode, the ic is turned off, reducing the supply current to 0.01? (typ). when the max1577y/max1577z are shut down, c1 is discharged and the output is pulled to gnd through an internal 5k ? resistor. figure 4. flash and backlighting with the max1577y max1577y c1 2.2 f* up to 1.2a 5.1v, 4.6v, or 3.4v v out - (300 or 100 or 60mv) camera-flashmovie light main displaybacklight 5.3v ovp 2.7v to 5.5v c in 4.7 f c in 10 f r cs 5.1v or 100% current, 4.6v or 33% current,3.4v or 20% current, and shutdown cp cn en1 in out cs gnd en2 rgb driver asic subdisplaybacklight *1 f for less than 600ma output. downloaded from: http:///
max1577y/max1577z 1.2a white led regulating charge pump for camera flashes and movie lights _______________________________________________________________________________________ 9 overvoltage protection output overvoltage protection (ovp) protects the ic and other components in case the output is open cir- cuit. the max1577z always limits the output voltage to 5.3v. with the max1577y, the output ovp voltage varies slightly depending on the state of the en_ inputs (see table 1). output-voltage regulation mode when the voltage across the sense resistor (v out - v cs ) is less than 24mv, the max1577y/max1577z reg- ulate the output voltage. for applications requiring afixed output voltage instead of current regulation, sim- ply connect cs directly to out as shown in figure 3. the max1577z regulates to a fixed 5.1v. the adjustable regulation voltage (3.4v, 4.6v, or 5.1v) of the max1577y depends on the state of the en_ inputs (see table 1). thermal protection thermal protection prevents damage to the ic duringoverload conditions. when the die temperature exceeds +160?, the max1577y/max1577z turn off until the die cools by 20?. once the die has cooled, the max1577y/max1577z turn on and initiate soft-start. during a continuous overload, this produces a pulsed output. continous operation at high-output-current set- tings may induce thermal protection. capacitor selection ceramic capacitors are recommended due to their lowequivalent series resistance (esr), small size, and low cost. select capacitors that maintain their capacitance over temperature and dc bias. typically x5r, x7r, or better ceramic capacitors perform well. a 4.7? input capacitor and 10? output capacitor are recommended for most applications. larger values can be used to reduce ripple. for the transfer capacitor (c1), a 1? capacitor is suit- able for output currents up to 600ma. for output cur- rents between 600ma and 1200ma, use a 2.2? capacitor. input ripple in 1x ldo mode there is no charge-pump switching,and thus very little input ripple. the input ripple in 2x charge-pump mode depends on the input source impedance. typical waveforms showing the ripple in 1x and 2x mode are in the typical operating characteristics . in sensitive applications, increase the input capacitance to reduce input ripple. applications information setting the output current for applications requiring a regulated output current,see the circuit of figure 2. the output regulation current is set by r cs as follows: r cs = (v out - v cs ) / i out where i out is the output current (up to 1200ma) and (v out - v cs ) is the current-sense threshold (see table 1). for camera-flash applications with a short pulse dura-tion, a 0.25w resistor is recommended. setting the output voltage to regulate the output voltage instead of the current,connect cs directly to the output as shown in figure 3. in this configuration the max1577z regulates the output to 5.1v. the output voltage of the max1577y is set to 5.1v, 4.6v, or 3.4v using the en1 and en2 inputs as shown in table 1. driving camera strobe/flash in applications that do not require dimming, such as acamera strobe/flash, connect en1 and en2 together and drive as a single on/off control input. pulse this input high to generate a strobe output. pwm dimming to vary the brightness from 20% to 100% using pulse-width modulation (pwm), hold en2 high and apply the pwm signal (up to 5khz) to en1. holding en2 high keeps the part enabled and prevents repeated soft- starts. the duty cycle of the pwm signal applied to en1 controls the brightness, where 0% duty cycle corre- sponds to 20% brightness and 100% duty cycle corre- sponds to 100% brightness. a pwm signal with a logic-high voltage between 1.6v and 5.5v can be safe- ly used regardless of the input voltage. the voltage of the pwm signal does not affect the brightness level. for highest movie-mode efficiency, it is best to choose r cs so 0% pwm duty cycle provides the desired movie-mode current. then, the flash current level isadjusted by the pwm duty cycle. when the movie- mode current is more than 33% of the flash current, it is more efficient to apply the pwm dimming signal to en2 while holding en1 high. ballast resistors for multiple leds when using multiple parallel leds, add a ballast resis-tor in series with each led to help balance the current between the leds. when using current regulation downloaded from: http:///
max1577y/max1577z 1.2a white led regulating charge pump for camera flashes and movie lights 10 ______________________________________________________________________________________ (figure 2), the ballast resistors must be small enough toprevent triggering the overvoltage protection: r ballast < (5.1v - v f ) / i led where i led is the current through each led and v f is the forward voltage of the led at i led . within this limit, larger values of r ballast improve led-to-led match- ing but also increase the input voltage where the 2xcharge pump makes the transition to the more efficient 1x ldo mode. when using voltage regulation (figure 3), select the ballast resistors based on the full brightness setting as follows: with en1 high and en2 high: r ballast = (5.1v - v f ) / i led the led current at the dimmed settings are calculatedas follows: with en1 high and en2 low: i led = (4.6v - v f ) / r ballast with en1 low and en2 high: i led = (3.4v - v f ) / r ballast note that v f varies as a function of i led . typically, led manufacturers provide a plot of forward voltage (v f ) vs. forward current (i led ) in the led data sheet. pc board layout and routing the max1577y/max1577z are high-frequency switched-capacitor regulators. for best circuit perfor- mance, use a solid ground plane and place c in , c out , and c1 as close to the ic as possible. connect the exposed pad to gnd directly under the ic and allow suf- ficient copper area for cooling. refer to the max1577z evaluation kit for an example pc board layout. chip information transistor count: 2482process: bicmos downloaded from: http:///
max1577y/max1577z 1.2a white led regulating charge pump for camera flashes and movie lights maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit 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 ____________________ 11 2004 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 l c l c pin 1 index area d e l e l a e number of leads shown are for reference only e2 detail a n f 1 2 21-0137 package outline, 6, 8, 10 & 14l, tdfn, exposed pad, 3x3x0.80 mm common dimensions symbol min. max. a0 . 7 00 .80 d2 . 9 03 .10 e2 . 9 03 .10 a1 0.00 0.05 l 0.20 0.40 pkg. code n d2 e2 e jedec spec b [(n/2)-1] x e package variations 0.25 min. k a2 0.20 ref. 2.300.10 1.500.10 6 t633-1 0.95 bsc mo229 / weea 1.90 ref f 2 2 21-0137 package outline, 6, 8, 10 & 14l,tdfn, exposed pad, 3x3x0.80 mm 0.400.05 1.95 ref 0.300.05 0.65 bsc 2.300.10 8 t833-1 2.00 ref 0.250.05 0.50 bsc 2.300.10 10 t1033-1 2.40 ref 0.200.03 - - - - 0.40 bsc 1.700.10 2.300.10 14 t1433-1 1.500.101.500.10 mo229 / weec mo229 / weed-3 0.40 bsc - - - - 0.200.03 2.40 ref t1433-2 14 2.300.10 1.700.10 downloaded from: http:///

▲Up To Search▲

Price & Availability of MAX1577YETAT

	To Download MAX1577YETAT Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .