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ap8800 350ma led step-down converter ap8800 rev. 4 1 of 13 december 2009 ds31764 www.diodes.com ? diodes incorporated ? led driving current up to 350ma ? compatible with 12v & 24v standard systems ? high efficiency up to 92% ? high switching frequency up to 0.6mhz ? pwm/dc input for dimming control ? built-in soft-start function ? built-in output open-circuit protection ? sop-8l, msop-8l and dfn3030-10 are available in ?green? molding compound (no br, sb) ? lead free finish/rohs compliant (note 1) the ap8800 is a step-down dc/dc converter designed to drive leds with a constant current. the device can drive up to seven leds, depending on the forward voltage of the leds, in series from a voltage source of 8v to 28v. series connection of the leds provides identical led currents resulting in uniform brightness and eliminates the need for ballast resistors. the ap8800 switches at frequency up to 0.6mhz. this allows the use of small size external components, hence minimizing the pcb area needed. maximum output current of ap8800 is set via an external resistor connected between the v in and set input pins. dimming is achieved by applying either a dc voltage or a pwm signal at the ctrl input pin. an input voltage of 0.2v or lower at ctrl shuts down the output at sw and puts the device into a low-current standby state. ? commercial & industrial lighting ? small lcd panel backlight ? architecture detail lighting ? appliances interior lighting typical applicat ion circuit figure 1: typical application circuit features general description applications
ap8800 350ma led step-down converter ap8800 rev. 4 2 of 13 december 2009 ds31764 www.diodes.com ? diodes incorporated ap 8800 xx g - x package packing s : sop-8l green 7/ 13 : tape & reel g : green m8 : msop-8l fn : dfn3030-10 device package code packaging (note 2) 7? / 13? tape and reel quantity part number suffix ap8800sg-13 s sop-8l 2500/tape & reel -13 ap8800m8g-13 m8 msop-8l 2500/tape & reel -13 ap8800fng-7 fn dfn3030-10 3000/tape & reel -7 notes: 1. eu directive 2002/95/ec (rohs). all applicable rohs exemptions applied. please visit our website at http://www.diodes.com/products/lead_free.html. 2. pad layout as shown on diodes inc. suggested pad layout document ap02001, which can be found on our website at http://www.diodes.com/datasheets/ap02001.pdf. ordering information
ap8800 350ma led step-down converter ap8800 rev. 4 3 of 13 december 2009 ds31764 www.diodes.com ? diodes incorporated (1) sop-8l (2) msop-8l 1 2 3 45 6 7 8 ( top view ) rsvd gnd sw nc ctrl set nc v in ap8800 1 2 3 45 6 7 8 ( top view ) rsvd gnd sw nc ctrl set nc v in ap8800 (3) dfn3030-10 ( top view ) 1 2 5 3 6 8 7 10 9 gnd rsvd nc ctrl sw nc v in nc set nc ap8800 4 pin name description sw switch pin. connect inductor/freewheeling diode here. minimize trace area at this pin to reduce emi. gnd gnd pin set set nominal output current pin. to configure the output current of the device. ctrl dimming and on/off control input. input voltage of 0.2v or lower forces the device into low current standby mode and shuts off the output. a pwm signal allows the output current to be adjusted above or below the level set by the resistor connected to set input pin. the input impedance is about 200k ? , and if the pin is left open v ctrl = v ref v in input supply pin. must be locally bypassed. rsvd reserved. normally connected to ground nc no connection. pin assignments pin descriptions
ap8800 350ma led step-down converter ap8800 rev. 4 4 of 13 december 2009 ds31764 www.diodes.com ? diodes incorporated block diagram voltage regulator 5v r ctrl v in gnd set sw comparator sensing block v ref 1.25v ap8800 pwm/dc control figure 2: ap8800 block diagram absolute maxi mum ratings symbol parameter rating unit v in vin pin voltage -0.3~30 v v sw sw voltage -0.3~30 v t j maximum junction temperature 125 o c t lead maximum lead temperature 300 o c t st storage temperature range -65 to +125 o c caution: the absolute maximum ratings are rated values exceeding which the product could suffer physical damage. these values m ust therefore not be exceeded under any condition. semiconductor devices are esd sensitive and may be damaged by exposure to esd events. suitable esd precautions should be taken when handling and transporting these devices. recommended oper ating conditions symbol parameter min max unit t a ambient temperature range -40 85 oc duty cycle using inductor 100h (note 3) 0.1 0.95 notes: 3. for most applications the led current will be within 8% over the duty cycle range specified. duty cycle accuracy i s also dependent on propagation delay. smaller size inductors can be used but led current accuracy may be greater than 8% at extremes of duty cycle . this is most noticeable at low duty cycles (less than 0.1) or when the input voltage is high and only one led is being driven.
ap8800 350ma led step-down converter ap8800 rev. 4 5 of 13 december 2009 ds31764 www.diodes.com ? diodes incorporated symbol parameter conditions min typ. max unit v in operating input voltage 8.0 - 28 v i out continuous switch current (note 4) - - 350 ma i q quiescient current - 20 30 a f osc switching frequency - 0.25 - mhz v thd internal threshold voltage 92 100 108 mv v ref internal reference voltage - 1.25 - v set set pin input current v set =v in -0.1 - 1.3 - a rds(on) on resistance of mosfet 1.7 2.2 ? i sw leaka g e switch leakage current - - 5 a en voltage high on 1.25 - - v en voltage low off - - 0.2 v t ja thermal resistance junction-to-ambient sop-8l (note 5) - 92 - q c/w msop-8l (note 5) - 120 - q c/w dfn3030-10 (note 5) - 46 - q c/w t jc thermal resistance junction-to-case sop-8l (note 5) - 60 - q c/w msop-8l (note 5) - 98 - q c/w dfn3030-10 (note 5) - 32 - q c/w notes: 4. refer to figure 5 for the device derating curve. 5. test condition for sop-8l, msop-8l and dfn3030-10: device mounted on fr-4 pcb, 2?x2?, 2oz copper, minimum recommended pad layout on top layer and thermal vias to bottom layer ground plane. for better thermal performance, larger coppe r pad for heat-sink is needed. electrical characteristics (v in =12v, t a =25 o c, unless otherwise specified) application information
ap8800 350ma led step-down converter ap8800 rev. 4 6 of 13 december 2009 ds31764 www.diodes.com ? diodes incorporated led current control the led current is controlled by the resistor rset in figure 1. if the ctrl pin is floating and at a nominal voltage of vref, the external current sense resistor rset (greater than 0.3 ? ) is connected between vin and set and defines the nominal average output current in the led(s) as: set thd led r v i if the ctrl pin is driven by an external voltage (lower than 2.5v), the average led current in this case is: set thd ref ctrl led r v v v i the graph in figure 3 gives values of nominal average output current for several values of current setting resistor (rset) in the typical application circuit shown on figure 1, for different voltages applied on the ctrl pin. led current versus rset and vctrl 0.3 0.33 0.39 0.47 0.56 3 0.56 0.68 0.75 0.82 1 1.2 3 0.3 0.39 0.47 0.56 0.68 0.82 1 1.2 1.5 2 3 1.2 1 0.82 0.68 1.5 2 1.5 2 0 50 100 150 200 250 300 350 400 0 0.15 0.3 0.45 0.6 0.75 0.9 1.05 1.2 1.35 1.5 1.65 1.8 1.95 2.1 2.25 2.4 2.55 2.7 2.85 3 rset value [ohms] led current [ma] led current @ vctrl = 1.25v led current @ vctrl = 2.5v led current @ vctrl = 0.625v figure 3: led current setting vs r set and v ctrl
ap8800 350ma led step-down converter ap8800 rev. 4 7 of 13 december 2009 ds31764 www.diodes.com ? diodes incorporated switching frequency 47 68 100 470 100 150 470 150 220 220 0 100 200 300 400 500 600 700 0 50 100 150 200 250 300 350 400 450 500 inductor value [uh] frequency [khz] 12v - 1led 24v - 3 leds 28v - 4leds figure 4: switching frequency vs supply voltage, inductor, and number of leds capacitor selection the small size of ceramic capacitors makes them ideal for ap8800 applications. x5r and x7r types are recommended because they retain their capacitance over wider voltage and temperature ranges than other types such as z5u. a 1 f input capacitor is sufficient for most intended applications of ap8800. diode selection schottky diode, e.g. b140, with their low forward voltage drop and fast reverse recovery, is the ideal choice for ap8800 applications. pwm dimming a pulse width modulated (pwm) signal with a max resolution of 8bit can be applied to the ctrl pin to regulate the output current to a value above or below the nominal average value set by resistor rset. miscellaneous to ensure optimal performance, rsvd pin should be connected to the gnd pin with the shortest trace length application information (continued)
ap8800 350ma led step-down converter ap8800 rev. 4 8 of 13 december 2009 ds31764 www.diodes.com ? diodes incorporated inductor selection a 100 h inductor is recommended for most ap8800 applications with input voltage at 24v. figure 4 displays the resulting switching frequency varying the main circuit parameters: supply voltage, inductor value and number of leds to be driven. thermal considerations the graph below in figure 5, gives details for power derating. this assumes the device to be mounted on a 25x25mm pcb with 1oz copper standing in still air. maximum power dissi pation 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0 25 50 75 100 125 150 ambient temperature (deg c) power (w) dfn3030-10 sop8 l msop8l figure 5: derating curve application information (continued)
ap8800 350ma led step-down converter ap8800 rev. 4 9 of 13 december 2009 ds31764 www.diodes.com ? diodes incorporated (1) sop-8l ( top view ) ap8800 yy ww x x logo part number 5 8 4 1 ww : week : 01~52; 52 yy : year : 08, 09,10~ g : green x : internal code represents 52 and 53 week (2) msop-8l ap8800 ( top view ) y w x part number logo y : year : 0~9 a~z : green 87 65 1 234 a~z : 27~52 week; z represents w : week : a~z : 1~26 week; 52 and 53 week (3) dfn3030-10 xx : identification code ( top view ) x : a~z : green xy x x w y : year : 0~9 w : week : a~z : 1~26 week; a~z : 27~52 week; z represents 52 and 53 week part number package identification code ap8800fng-7 dfn3030-10 a4 marking information
ap8800 350ma led step-down converter ap8800 rev. 4 10 of 13 december 2009 ds31764 www.diodes.com ? diodes incorporated (1) package type: sop-8l 1.27typ 0.3/0.5 7~9 4.85/4.95 3.85/3.95 5.90/6.10 0.15/0.25 7~9 0.62/0.82 0.10/0.20 gauge plane 0.254 seating plane 0.35max. 45 detail "a" detail "a" 1.30/1.50 1.75max. land pattern recommendation (unit: mm) 6x-1.27 8x-1.55 8x-0.60 5.4 0/8 (2) package type: msop-8l 2.9/3.1 0.75/0.95 0/0.15 2.9/3.1 4.7/5.1 0.65bsc. 0.22/0.38 0.05 0.15typ. 0.4/0.8 0.25 0.95ref. gauge plane 0 / 8 "a" detail "a" 1 6x-0.65 land pattern recommendation (unit:mm) 8x-1.4 4.4 8x-0.45 0.05/0.15 package information (all dimensions in mm)
ap8800 350ma led step-down converter ap8800 rev. 4 11 of 13 december 2009 ds31764 www.diodes.com ? diodes incorporated (3) package type: dfn3030-10 bottom view side view 0.57/0.60 0/0.05 0.15typ. 0.10 c 0.08 c seating plane c 2.9/3.1 2.3/2.5 2.9/3.1 0.50typ. 0.2/0.3 1.5/1.7 (pin #1 id) a b 0.10 c ab 0.25 a 2x- 0.25 b 2x- 0.25/0.55 r 0 . 3 0 0 0.375typ. top mark package information (continued)
ap8800 350ma led step-down converter ap8800 rev. 4 12 of 13 december 2009 ds31764 www.diodes.com ? diodes incorporated for dfn3030-10 notes: 6. the taping orientation of the other package type can be found on our website at http://www.diodes.com/datasheets/a p02007.pdf. taping orientation (note 6)
ap8800 350ma led step-down converter ap8800 rev. 4 13 of 13 december 2009 ds31764 www.diodes.com ? diodes incorporated important notice diodes incorporated makes no warranty of any kind, express or implied, with regarding to this document, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose (and their equivalents under the laws of any jurisdiction). diodes incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or ot her changes without further notice to this document and any product described herein. diodes incorporated does not assume any liability arising out of the application or use of this document or any product described herein; neither does diodes incorpora ted convey any license under its patent or trademark rights, nor the rights of others. any customer or user of this document or pr oducts described herein in such applications shall assume all risks of such use and will agree to hold diodes incorporated and all the companies whose products are represented on diodes incorporated website, harmless against all damages. diodes incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthoriz ed sales channel. should customers purchase or use diodes incorporated products for any unintended or unauthorized application, customers shall indemnify and hold diodes incorporated and its representatives harmless against all claims, damages, expenses, and attorney fee s arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized application. products described herein may be covered by one or more united states, international or foreign patents pending. product names and markings noted herein may also be covered by one or more united states, international or foreign trademarks. life support diodes incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express written approval of the chief executive officer of diodes incorporated. as used herein: a. life support devices or systems are devices or systems which: 1. are intended to implant into the body, or 2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. b. a critical component is any component in a life support device or system whose failure to perform can be reasonably expect ed to cause the failure of the life support device or to affect its safety or effectiveness. customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support dev ices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of diodes incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related information or support that may be provided by diodes incorporated. further, customers must fully indemnify diodes incorporated and its representatives against any damages arising out of the use of diodes incorporated products in such safety-critical, life support devices or systems. copyright ? 2009, diodes incorporated www.diodes.com

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