general description the max8607 white led boost converter is optimized for camera flash/strobe applications using high-current white leds. the max8607 integrates a 1mhz pwm boost converter, 1.5a low-dropout (ldo) current regu- lator, and logic control circuitry for a space-saving led flash design. two logic inputs control four modes of operation: shutdown mode reduces the quiescent cur- rent to 0.1? (typ), movie mode supplies up to 360ma of led current for continuous lighting, flash mode sup- plies up to 1.5a of led current for short-duration light- ing during an exposure, and disco mode supplies +5v (at up to 1a) to external circuits while driving the led with a fixed 80ma current. the internal 1mhz boost converter features an adaptive control scheme with an internal switching mosfet and synchronous rectifier to improve efficiency and mini- mize external component count. the max8607 is avail- able in a 14-pin, 3mm x 3mm tdfn package (0.8mm max height). applications camera flashes/strobes cell phones/smartphones pdas and digital cameras features ? supports lumileds and other high-power white leds ? independently set flash/movie currents flash-mode current up to 1.5a movie-mode current up to 360ma ? disco mode with fixed 5v (up to 1a) and 80ma led current ? 84% efficiency (p led / p batt ) at 1.1a ? t a derating function for led thermal protection ? output overvoltage protection (ovp) ? soft-start eliminates inrush current ? 1mhz pwm operation at all loads ? small external components ? 2.7v to 5.5v input voltage range ? 0.1a shutdown mode ? 14-pin, 3mm x 3mm tdfn package max8607 1mhz pwm boost converter for 1.5a white led camera flash ________________________________________________________________ maxim integrated products 1 lgnd flsh gnd mov en1 en2 comp led pgnd pgnd lx out lx outs max8607 tdfn 3mm x 3mm top view 245 13 11 10 1 + 14 3 12 6 9 7 8 pin configuration ordering information lx pgnd output lgnd comp flsh mov out en1 en2 led input 2.7v to 5.5v outs up to 1.5a flash up to 360ma movie gnd mode- select inputs 10 f 10 f 2.2 h max8607 t ypical operating circuit 19-3783; rev 1; 2/07 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 * pin-package top mark MAX8607ETD+ 14 tdfn 3mm x 3mm (t1433-1) aba + indicates lead-free package. * the MAX8607ETD is characterized over the -40? to +85? temperature range.
max8607 1mhz pwm boost converter for 1.5a white led camera flash 2 _______________________________________________________________________________________ absolute maximum ratings 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. out, outs, en1, en2 to gnd ................................-0.3v to +6v flsh, mov, led, comp, lx to gnd ....-0.3v to (v outs + 0.3v) lgnd, pgnd to gnd. ..........................................-0.3v to +0.3v lx current. ........................................................................2a rms continuous power dissipation (t a = +70?) 14-pin tdfn 3mm x 3mm (derate 18.2mw/? above +70?)..............................................................1455mw operating temperature range ...........................-40? to +85? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? electrical characteristics (v en1 = v en2 = 5v, v out = v outs = 4v, c out = 10?, t a = -40? to +85?. typical values are at t a = +25?, unless otherwise noted.) (note 1) parameter conditions min typ max units supply voltage ic supplied from outs 2.7 5.5 v undervoltage-lockout threshold v outs rising, 100mv (typ) hysteresis 2.25 2.38 2.65 v out quiescent current, flash or movie mode lx switching, i led = 0ma 4 ma t a = +25? 0.1 1 out quiescent current, shutdown mode en1 = en2 = gnd t a = +85? 1 ? overvoltage limit, i led = 0ma, v led = 0v 5.3 5.5 5.7 v led = 0.5v 3.65 3.85 3.95 out regulation voltage disco mode, i led = 80ma 4.8 5.0 5.2 v t a = +25? 0.01 1 led current, shutdown mode en1 = en2 = gnd t a = +85? 0.5 ? flash mode 1200 1500 movie mode 338 360 current-source guaranteed sink current r mov = 2k ? , r flsh = 2k ? , v led = 0.5v disco mode 80 ma current-source multiplier in mov mode (i led / i mov) i mov up to 300? 1200 a/a t a 0? (note 2) -3 ?.5 +3 current-source accuracy in mov mode r mov = 2k ? , v led = 0.5v t a = -40? -6 ?.5 +6 % mov current-source dropout voltage r mov = 2k ? 48 100 mv disco current-source current setting v en1 = 0v, v en2 = 5v 62 80 108 ma current-source multiplier in flsh mode (i led / i flsh) i flsh up to 300? 5000 a/a current-source accuracy in flsh mode r flsh = 2k ? , v led = 0.5v, t a -40? (note 2) ? % flsh current-source dropout voltage r flsh = 2k ? =
max8607 1mhz pwm boost converter for 1.5a white led camera flash _______________________________________________________________________________________ 3 electrical characteristics (continued) (v en1 = v en2 = 5v, v out = v outs = 4v, c out = 10?, t a = -40? to +85?. typical values are at t a = +25?, unless otherwise noted.) (note 1) parameter conditions min typ max units comp input resistance to gnd during shutdown or uvlo 140 250 ? led t a derating function threshold temperature when the led current derating function begins +40 ? led t a derating function slope t a = +40? to +85? -1.67 %/? en1 and en2 logic-high input voltage v outs = 2.7v to 5.5v 1.4 v en1 and en2 logic-low input voltage v outs = 2.7v to 5.5v 0.4 v t a = +25? 0.01 1 en1 and en2 logic input bias current v en_ = 5.5v t a = +85? 0.03 ? lx n-channel on-resistance i lx = 200ma 50 100 m ? lx p-channel on-resistance i lx = 200ma 100 200 m ? t a = +25? 0.01 1 lx leakage v lx = 5.5v t a = +85? 0.03 ? operating frequency 0.8 1.0 1.2 mhz maximum duty cycle 65 75 % minimum duty cycle 48% note 1: all devices are production tested at t a = +25?. specifications over temperature are guaranteed by design and characteri- zation and not production tested. note 2: for temperatures below the thermal derating start point. t ypical operating characteristics (circuit of figure 2, v in = v en1 = 3.6v, v en2 = 0v, t a = +25?, unless otherwise noted.) flash-mode battery current vs. input voltage max8607toc01 0 500 1500 1000 3000 3500 2500 2000 4000 battery current (ma) 2.7 3.5 3.9 3.1 4.3 4.7 5.1 5.5 input voltage (v) r flsh = 4.02k ? r flsh = 8.06k ? r flsh = 3.01k ? r flsh = 2k ? movie-mode battery current vs. input voltage max8607toc02 0 100 300 200 500 400 600 battery current (ma) 2.7 3.5 3.9 3.1 4.3 4.7 5.1 5.5 input voltage (v) r mov = 2.00k ? r mov = 3.57k ? r mov = 6.49k ? 100 80 10 100 1000 boost converter efficiency vs. load current (disco mode) 82 max8607toc03 load current (ma) efficiency (%) 88 94 84 90 96 86 92 98 includes 83ma led current
max8607 1mhz pwm boost converter for 1.5a white led camera flash 4 _______________________________________________________________________________________ led current vs. ambient temperature max8607toc04 0 50 150 100 300 350 250 200 400 led current (ma) -40 0 20 -20 40 60 80 ambient temperature ( c) ic supply current vs. input voltage max8607toc05 0 100 300 200 600 800 700 900 500 400 1000 supply current ( a) 2.7 3.5 3.9 3.1 4.3 4.7 5.1 5.5 input voltage (v) disco mode movie mode flash mode switching waveforms (movie mode) max8607toc06 v in v lx i l v out 10mv/div 5v/div 100ma/div 20mv/div 400ns/div soft-start response (standby to movie-mode transition) max8607toc07 v en1 v out i in i led 200ma/div 2v/div 100ma/div 5v/div 0a 0v 0a 0v 100 s/div soft-start response (movie-mode to flash transition) max8607toc08 v en2 v out i in i led 200ma/div 2v/div 500ma/div 0a 0v 0a 5v/div 400 s/div load transient (disco mode) max8607toc09 v out(ripple) i l0ad 100ma 500mv/div 700ma 2ms/div t ypical operating characteristics (continued) (circuit of figure 2, v in = v en1 = 3.6v, v en2 = 0v, t a = +25?, unless otherwise noted.)
max8607 1mhz pwm boost converter for 1.5a white led camera flash _______________________________________________________________________________________ 5 400 0 110 100 movie-mode led current vs. mov resistance 100 max8607toc10 r mov (k ? ) led current (ma) 200 300 50 150 250 350 1600 0 110 100 flash-mode led current vs. flsh resistance 400 max8607toc11 r flsh (k ? ) led current (ma) 800 1200 200 600 1000 1400 t ypical operating characteristics (continued) (circuit of figure 2, v in = v en1 = 3.6v, v en2 = 0v, t a = +25?, unless otherwise noted.) pin description pin name function 1 comp compensation input. connect a 0.1? ceramic capacitor from comp to gnd for regulator stability. 2 en1 enable input 1. en1 and en2 set the operating mode (see table 1). 3 en2 enable input 2. en1 and en2 set the operating mode (see table 1). 4 mov movie current program input. connect a resistor from mov to gnd to set the led current in movie mode. r mov must be greater than 2k ? . 5 flsh flash current program input. connect a resistor from flsh to gnd to set the led current in flash mode. r flsh must be greater than 2k ? . 6 gnd analog ground. connect gnd to the exposed paddle directly under the ic. 7 lgnd led current regulator ground. connect lgnd to the ground plane on the pc board. 8 led le d c ur r ent reg ul ator . c onnect le d to the cathod e of the exter nal le d . le d i s hi g h im p ed ance d ur i ng shutd ow n. 9, 10 pgnd p ow er gr o und . c onnect p gn d to the i np ut cap aci tor g r ound . al so , connect p gn d to the p c b oar d g r ound p l ane. 11, 12 lx inductor connection. connect lx to the switched side of the inductor. lx is internally connected to the drains of the internal mosfets. both mosfets are off during shutdown. 13 out regulator output. connect out to the anode of the external led. bypass out to pgnd with a 10? or larger ceramic capacitor. during shutdown, out is one body-diode drop below the input voltage. 14 outs outp ut s ense and ic s up p l y inp u t. c o nnect ou ts to ou t at th e outp ut b yp ass cap aci tor . the ic ? s op er ati ng p ow er i s sup p l i ed fr om ou ts . ?p exposed paddle. connect the exposed paddle to gnd directly under the ic and to a large pc board ground plane for increased thermal performance.
max8607 detailed description boost converter the max8607 includes a fixed-frequency, pwm boost converter that supplies the led current. the output voltage is adaptively controlled to provide adequate headroom with varying led forward voltage. the boost converter switches an internal power mosfet and syn- chronous rectifier at a constant 1mhz frequency with varying duty cycle up to 75% to maintain constant led current over the 2.7v to 5.5v input range. internal spe- cial circuits prevent any unwanted subharmonic switch- ing in the critical buck/boost region. ldo current regulator (led) a low-dropout (ldo) linear current regulator from led to lgnd sinks current from the external led? cathode terminal. the led current is regulated to a user-pro- grammable level. in movie mode, the current into led is regulated to 1200 times the current set by the mov resistor (r mov ). in flash mode, the current into led is regulated to 5000 times the current set by the flsh resistor (r flsh ). in disco mode, the current into led is regulated to 80ma. 1mhz pwm boost converter for 1.5a white led camera flash 6 _______________________________________________________________________________________ lx pgnd comp en1 en2 flsh mov gnd forced-pwm boost control outs out ref shutdown and mode control 1mhz clock feedback select ldo regulator led lgnd 1.25v max8607 figure 1. functional diagram
mode-select inputs (en1, en2) drive en1 high and en2 low to enable movie mode. in this mode, the current regulator regulates the current through the led to 1200 times the current set by the mov resistor. see the setting the movie-mode current section for details on setting the movie-mode current. drive en1 and en2 high to enable flash mode. in this mode, the current through the led is regulated to 5000 times the current set by the flsh resistor. see the setting the flash-mode current section for details on set- ting the flash-mode current. the time duration of the flash mode must be set using external circuitry or software. drive en1 low and en2 high to enable disco mode. in this mode, the output of the boost converter provides a regulated +5v at up to 1a for external circuitry, while the led current is regulated to 80ma. the led current is not adjustable in this mode. drive en1 and en2 low to place the ic into a low- power shutdown mode. see the shutdown section for more details. overvoltage protection the output voltage of the max8607 is limited by internal overvoltage-protection (ovp) circuitry, which prevents the output from exceeding 5.7v under any conditions. in flash and movie modes, if the output voltage nears 5.5v, the led current is smoothly reduced through pro- prietary means to prevent overvoltage without sudden termination of the output current. in case of an led with very high forward voltage (v f ), this circuit provides more reliable and repeatable flash than would a simple on/off comparator. in disco mode, the output is limited by the internal 5.0v regulation. undervoltage lockout the max8607 contains undervoltage-lockout (uvlo) circuitry that disables the ic until v outs is greater than 2.38v. prior to startup, v outs is one diode drop below the input voltage. this ensures a great enough input voltage for startup. soft-start the max8607 attains soft-start by charging c comp with a 100? current source. during this time, the inter- nal mosfet is switching at the minimum duty cycle. once v comp rises above 1v, the duty cycle increases until output reaches the desired regulation level. comp is pulled to gnd with a 140 ? internal resistor during uvlo, ovp, or shutdown. see the typical operating characteristics for an example of soft-start operation. shutdown drive en1 and en2 low to place the max8607 into a low-power shutdown mode. in shutdown, supply cur- rent is reduced to 0.1? (typ). c comp is discharged during shutdown, allowing the device to reinitiate soft- start when it is enabled. the internal mosfet and syn- chronous rectifier are turned off during shutdown; however, out is one body-diode drop below the input. led is high impedance so the external led is off, but any external circuitry on out is not disconnected and, therefore, should include its own shutdown capability. typical shutdown timing characteristics are shown in the typical operating characteristi cs. ambient temperature derating function the max8607 limits the maximum led current depend- ing on its die temperature. once the die temperature reaches +40?, the led current decreases by 1.67% per ?. this corresponds to approximately 0ma of led current at +100?. due to the package? exposed pad- dle, the die temperature is very close to the pc board temperature. the temperature derating function allows the led current to be safely set higher at normal oper- ating temperatures, thereby allowing either a brighter flash or movie light to be used for normal ambient tem- peratures. see the typical operating characteristics for a graph of led current vs. ambient temperature. applications information setting the movie-mode current to set the led current during movie mode, connect a resistor from mov to gnd (r mov ). v mov is regulated to 0.6v and the current through r mov is mirrored to led with a gain of 1200. r mov is calculated as: r mov = (0.6v x 1200) / i led(mov) setting the flash-mode current to set the led current during flash mode, connect a resistor from flsh to gnd (r flsh ). v flsh is regulated to 0.6v and the current through r flsh is mirrored to led with a gain of 5000. r flsh is calculated as: r flsh = (0.6v x 5000) / i led(flsh) max8607 1mhz pwm boost converter for 1.5a white led camera flash _______________________________________________________________________________________ 7 en1 en2 mode 00 shutdown 01 disco mode 10 movie mode 11 flash mode table 1. en1 and en2 mode selection
max8607 inductor selection the max8607 is designed to use a 2.2? inductor. to prevent core saturation, ensure that the inductor-satura- tion current rating exceeds the peak inductor current for the application. calculate the worst-case peak inductor current with the following formula: table 2 provides a list of suggested inductors. capacitor selection bypass the input to pgnd using a ceramic capacitor. place the capacitor as close to the ic as possible. the exact value of the input capacitor is not critical. the typical value for the input capacitor is 10?; however, larger value capacitors can be used to reduce input ripple at the expense of size and higher cost. the output capacitance required depends on the required led current. a 10? ceramic capacitor works well in most situations, but a 4.7? capacitor is accept- able for load current below 300ma. pc board layout due to fast switching waveforms and high-current paths, careful pc board layout is required. connect gnd directly to the exposed paddle underneath the ic; con- nect the exposed paddle to the pc board ground plane. connect lgnd and pgnd to the ground plane. the out- put bypass capacitor should be placed as close to the ic as possible. c comp should be connected from comp to gnd as close to the ic as possible. minimize trace lengths between the ic and the inductor, the input capacitor, and the output capacitor; keep these traces short, direct, and wide. the ground connections of c in and c out should be as close together as possible and connected to pgnd. the traces from the input to the inductor and from the output capacitor to the led may be longer. a sample layout is available in the max8607 evaluation kit (max8607evkit) to speed design. chip information process: bicmos i vi v vs h peak led max in min in min = + 5 09 05 222 () () () . . . 1mhz pwm boost converter for 1.5a white led camera flash 8 _______________________________________________________________________________________ lx pgnd lgnd comp flsh mov out en1 en2 led input 2.7v to 5.5v outs gnd mode- select inputs c2 10 f l1 2.2 h max8607 ep r2 r1 5 4 2 3 1 c3 0.1 f c1 10 f 9, 10 11, 12 13 14 7 6 8 d1 u1 figure 2. typical application circuit manufacturer series inductance (h) dcr (m ? ) i sat (a) dimensions (l typ x w typ x h max = volume) coilcraft lpo3310 2.2 150 1.1 3.3 x 3.3 x 1.0 = 11mm 3 cooper (coiltronics) sd3114 2.2 83 1.48 3.0 x 3.0 x 1.45 = 13mm 3 mipf2520 2.2 80 0.7 2.5 x 2.0 x 1.0 = 5mm 3 fdk mipw3226 2.2 100 1.1 3.2 x 2.6 x 1.0 = 8mm 3 de2812c 2.2 70 1.6 3.0 x 2.8 x 1.2 = 10mm 3 toko fdse0312 2.2 160 2.3 3.0 x 3.0 x 1.2 = 11mm 3 table 2. suggested inductors
max8607 1mhz pwm boost converter for 1.5a white led camera flash _______________________________________________________________________________________ 9 max8607 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
max8607 1mhz pwm boost converter for 1.5a white led camera flash 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. 10 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2007 maxim integrated products is a registered trademark of maxim integrated products, inc. package information (continued) (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 .) 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 n d2 e2 e jedec spec b [(n/2)-1] x e package variations 0.25 min. k a2 0.20 ref. 2.00 ref 0.250.05 0.50 bsc 2.300.10 10 t1033-1 2.40 ref 0.200.05 - - - - 0.40 bsc 1.700.10 2.300.10 14 t1433-1 1.500.10 mo229 / weed-3 0.40 bsc - - - - 0.200.05 2.40 ref t1433-2 14 2.300.10 1.700.10 t633-2 6 1.500.10 2.300.10 0.95 bsc mo229 / weea 0.400.05 1.90 ref t833-2 8 1.500.10 2.300.10 0.65 bsc mo229 / weec 0.300.05 1.95 ref t833-3 8 1.500.10 2.300.10 0.65 bsc mo229 / weec 0.300.05 1.95 ref 2.300.10 mo229 / weed-3 2.00 ref 0.250.05 0.50 bsc 1.500.10 10 t1033-2 revision history pages changed at rev 1: 1, 2, 9, 10
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