3w h igh power white led driver 2007-7-13 1 / 6 FSP3604 ? applications z white led torch (flashlight) z white led camera flash z dsc (digital still camera)flash z cellular camera phone flash z pda camera flash z camcorder torch (flashlight) lamp ? pin configuration (top view) ? typical application circuit pin number pin name pin function 1 sw power switch pin. 2 gnd ground pin 3 fb feedback pin 4 shdn chip shutdown signal input 5 vout power output pin. 6 vin power supply input. ? features z led power efficiency: up to 90% z 1mhz switching frequency z uses small, low profile external components z low start-up voltage: 0.9v(i led =270ma) z low r ds(on) : 100m ? (typ.) z open led protection z over temperature protection z low profile sot23-6l package ? general description the FSP3604 is a step up dc-dc converter that delivers a regulated out put current. the device switches at a 1.0mhz constant frequency, allowing for the use of small value external inductor and ceramic capacitors. the FSP3604 is targeted to be used for driving loads up to 1a from a two-cell alkaline battery. the led current can be programmed by the external current sense resistor, rs, connected between the feedback pin (fb) and ground. a low 95mv feedback voltage reduces the power loss in the rs for better efficiency. with its internal 2a, 100m ? nmos switch, the device can provide high efficiency even at heavy load. during the shutdown mode, the feedback resistor rs and the load are completely disconnected and the current consumption is reduced to less than 1ua. 2 3 6 54 1 sw gnd fb vin vout shdn
3w h igh power white led driver 2007-7-13 2 / 6 FSP3604 ? absolute maximum ratings (note 1) parameter rating unit v in - 0.3 ~ +6 v v sw - 0.3 ~ +6 a fb shdn voltages - 0.3 ~ +6 operating temperature range - 40 ~ +85 operating junction temperature -40~+125 lead temperature (soldering 5 sec.) + 300 internal power dissipation 400 mw 250( ja ) thermal resistance 130( jc ) /w storage temperature range - 65 ~ +125 note 1: absolute maximum ratings are those values beyond which the life of a device may be impaired. ? electrical characteristics (v in = 2.4v, i led =750ma, v shdn =v in , l=2.2uh, c in =10uf, c o =10uf, t a =25 , unless otherwise noted) parameter condition min. typ. max. unit input voltage range 0.9 v f -0.2 (note 2) v start-up voltage v in : 0v 2.4v, i led = 100ma 0.7 0.9 v hold voltage v in : 2.4v 0v, i led : 750ma 200ma 0.75 v switching frequency 0.85 1.0 1.15 mhz shdn input high v in = 1.8v 1.0 shdn input low v in = 1.8v 0.4 v feedback voltage 90 95 100 mv over temperature shutdown 150 over temperature hysteresis 15 maximum output current range 750 ma quiescent current i led = 0ma, v o = 3.4v device switching at 1mhz 1 3 ma shutdown current shutdown mode 1 ua switch on resistance v o = 3.4v 0.1 ? current limit v o = 3.4v 2 a efficiency i led = 750ma 90 % note 2: vf: led forward voltage
3w h igh power white led driver 2007-7-13 3 / 6 FSP3604 ? functional block diagram ? application information inductor selection the FSP3604 can use small value inductors due to its switch ing frequency of 1 mhz. the value of inductor will focus in the range of 2.2uh to 4.7uh for most FSP3604 applications . in typical high current white led applications, it is recommended to use a 4.7uh inductor. the inductor should have low dcr (dc resistance) to minimize the i 2 r power loss, and it requires a current rating of 2a to handle the peak inductor current without saturating. capacitor selection an input capacitor is required to reduce the input ripp le and noise for proper operation of the FSP3604. for good input decoupling, low esr (equivalent series resistance) capacitors should be used at the input. at least 2.2uf input capacitor is recommended for most applications. a minimum output capacitor value of 6.8uf is recommende d under normal operating conditions, while a 10uf-22uf capacitor may be required for higher power led current. a reasonable value of the output capacitor depends on the led current. the esr of the output capa citor is the important parameter to determine the output voltage ripple of the converter, so low esr capacitors should be used at the output to reduce the output voltage ripple. the small size of ceramic capacitors is an excellent choice for FSP3604 applications. the x5r and x7r types are preferred because they maintain capacitance over wide voltage and temperature ranges. diode selection it's indispensable to use a schottky diode rated at 2a with the FSP3604. using a schottky diode with a lower forward voltage drop is better to improve the power led effici ency, and its voltage rating should be greater than the output voltage. in application, the on semiconductor mbra210lt3g is recommended. led current setting the led current is set by the single exte rnal rs resistor connected to the fb pin as shown in the typical application circuit on page 1. the typical fb reference is interna lly regulated to 95mv. the led current is 95mv/rs. it's recommended to use a 1% or better precision resistor for the better led current accuracy. the formula and table 1 for rs selection are shown as follows: rs=95mv/i table 1. rs resistor value selection
3w h igh power white led driver 2007-7-13 4 / 6 FSP3604 pcb layout guidelines as for all switching power supplies, the layout and com ponents placement of the FSP3604 is an important step in the design; especially at high peak currents and high switching frequencies. the input capacitor and output capacitor should be placed respectively as close as possible to the input pin and output pin of the ic; the inductor and schottky diode should be pl aced as close as possible to the switch pin by using wide and short traces for the main current path; the curren t sense resistor should be placed as close as possible between the ground pin and feedback pin. ? typical characteriscits (l=2.2uh, c in =10uf, c o =10uf, t a =25 , unless otherwise noted)
3w h igh power white led driver 2007-7-13 5 / 6 FSP3604 ? typical characteris cits (continued) (l=2.2uh, c in =10uf, c o =10uf, t a =25 , unless otherwise noted) ? ordering information ? marking information FSP3604xxx package: c: sot23-6l packing: a: tape & reel temperature grade: d: -40~85 xxvyw voltage code product code date code: y: year (1=2001) w: week (a~z, a~z)
3w h igh power white led driver 2007-7-13 6 / 6 FSP3604 ? package information dimensions in millimeters dimensions in inches symbol min. max. min. max. a 0.900 1.450 0.036 0.058 a1 0.000 0.150 0.000 0.006 a2 0.900 1.300 0.036 0.052 b 0.300 0.500 0.012 0.020 c 0.100 0.200 0.004 0.008 d 2.800 3.100 0.112 0.124 e 2.50 3.100 0.100 0.124 e1 1.500 1.700 0.060 0.068 l 0.200 0.550 0.002 0.022 e 0.95 bsc. 0.038 bsc. e1 1.90 bsc. 0.076 bsc. 0 8 0 8 e1 d e b e1 e 6 4 3 2 1 5 a a1 a2 l c
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