pam2803 document number: ds 36400 rev. 2 - 2 1 of 9 www.diodes.com december 2014 ? diodes incor porated pam2803 a product line of diodes incorporated 3w high power white led driver description the pam2803 is a s t ep - up dc - dc converter that delivers a regulated output current. the device switches at a 1.0mhz constant frequency, allowing for the use of small value external inductor and ceram ic capacitors. the pam2803 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, r s , connected between the feedback pin (fb) and ground. a low 95mv fee dback 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 r s and the load are completely disconn ected and the current consumption is reduced to less than 1a. the pam2803 is available in the 6 - lead sot23 - 6 package. features ? led power efficiency: up to 90% ? current accuracy: 5%(v in = 3.6v to 1.8v @v f = 3.7v) ? low start - up voltage: 0.9v (i led = 270ma) ? low hold voltage: 0.75 (i led = 200ma) ? 1mhz switching frequency ? uses small, low profile external components ? low r ds(on) : 1 00m (typ) ? over t emperature protection ? low profile sot23 - 6 package ? pb - free package pin assignments applications ? white led torch (flashlight) ? white led camera flash ? dsc (digital still camera) flash ? cellular camera phone f lash ? pda camera flash ? camcorder torch (flashlight) lamp typical applications circuit i led = 750ma, r s = 0.127?
pam2803 document number: ds 36400 rev. 2 - 2 2 of 9 www.diodes.com december 2014 ? diodes incor porated pam2803 a product line of diodes incorporated pin description pin number pin name function 1 sw switch 2 gnd ground 3 fb feedback 4 shdn shut down 5 vout output 6 vin input block diagram absolute maximum ratings (@ t a = +25c, unless otherwise specified.) these are stress ratings only and functional operation is n ot implied. exposure to absolute maximum ratings for prolonged time per iods may affect device re liability. all voltages are with respect to ground . parameter rating unit input pin voltage - 0.3 to +6 v sw pin voltage - 0.3 to +6 shdn, fb pin voltage - 0.3 to +6 operating temperature range - 40 to +85 c storage temperat ure range - 65 to +125 lead temperature (soldering, 5 sec) 300 recommended operating conditions (@ t a = +25c, unless otherwise specified.) parameter rating unit junction temperature - 40 to +125 c ambient temper a ture - 40 to +85
pam2803 document number: ds 36400 rev. 2 - 2 3 of 9 www.diodes.com december 2014 ? diodes incor porated pam2803 a product line of diodes incorporated thermal information parameter symbol package max unit thermal resistance (junction to case) jc sot23 - 6 130 c/w thermal resistance (junction to ambient) ja sot23 - 6 250 internal power dissipation p d sot23 - 6 400 mw electrical characteristics (@ t a = +25c, v in = 2.4 v, i led = 750ma, v shdn = v in , l = 2.2h, c in = 1 0 f, c o = 10 f , unless oth erwise specified.) parameter symbol test conditions min typ max units input voltage range v in ? ? f - 0.2 (note 1) v feedback voltage v fb ? start v in : 0v C led = 370ma ? ? hold v in : 3v C led : 750ma C ? osc ? sh v in = 1.8v 1.0 ? ? sl v in = 1.8v ? ? ? ? ? ? ? ? o(max) ? ? ? q i led = 0ma, v o = 3.4v, device switching @ 1mhz ? sd shutdown mode ? ds(on) v o = 3.4v ? ? ? lim v o = 3.4v 2 ? ? led = 750ma ? ? note: 1. vf C led forward voltage.
pam2803 document number: ds 36400 rev. 2 - 2 4 of 9 www.diodes.com december 2014 ? diodes incor porated pam2803 a product line of diodes incorporated typical performance characteristics ( @ t a = +25c, l = 2.2 f, c in = 10f, c o = 10 f , unless otherwise specified.)
pam2803 document number: ds 36400 rev. 2 - 2 5 of 9 www.diodes.com december 2014 ? diodes incor porated pam2803 a product line of diodes incorporated typical pe rformance characteristics (cont.) @ t a = +25c, l = 2.2f, c in = 10f, c o = 10f, unless otherwise specified.)
pam2803 document number: ds 36400 rev. 2 - 2 6 of 9 www.diodes.com december 2014 ? diodes incor porated pam2803 a product line of diodes incorporated application information inductor selection the pam2803 can use small value inductors due to its switching frequency o f 1 mhz. the value of inductor will focus in the range of 2.2h to 4.7 h for most pam2803 applications. in typical high current white le d applications, it i s recommended to use a 4.7 h inductor. the inductor should have low dcr (dc resistance) to minimize t he 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 ripple and noise for proper operation of the pam2803. for good input d ecoupling, low esr (equivalent series resistance) capacitors should be used at the input. at least 2.2 f input capacitor is recommended for most applications. a minimu m output capacitor value of 6.8 f is recommended under normal operatin g conditions, whil e a 10f - 22 f capacitor may be required for higher power led current. a reasonable value of the output capaci tor depends on the led current. the esr of the output capacitor 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 pam2803 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 pam2803. using a schottky diode with a lower forward voltage drop is better to improve the power led efficiency, and its voltage rating should be greater than the output voltage. in applicat i on, the on semi conducto r mbra210lt3g is recommended. led current setting the led current is set by the single external r s resistor connected to the fb pin as shown in the typical application circuit on p age 1. the typical fb reference is internally regulated to 95mv. the led current is 95mv/r s . it's recommended to use a 1% or better precision resistor for the better led current accuracy. the formula and table 1 for r s selection are shown as follows: table 1. r s resistor value selection standard value (?) i led (ma) 0.18 528 0.15 633 0.12 792 0.10 950 pcb layout guidelines as for all switching power supplies, the layout and components placement of the pam2803 is an important step in the design; especially at high peak currents and hig h switchin g 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 placed as close as possible to the switch pin by usin g wide and short traces for the main current path; the current sense resistor should be placed as close as possible between the ground pin and feedback pin. i / mv 95 r led s ?
pam2803 document number: ds 36400 rev. 2 - 2 7 of 9 www.diodes.com december 2014 ? diodes incor porated pam2803 a product line of diodes incorporated ordering information part number marking package type standard package PAM2803AAF095 refer to marking information below sot23 - 6 3 , 000 units/tape&reel marking information p a m 2 8 0 3 x x x x p i n c o n f i g u r a t i o n f : 6 a t y p e : 1 . s w 2 . g n d 3 . f b 4 . s h d n 5 . v o u t 6 . v i n a : s o t 2 3 - 6 p a c k a g e t y p e n u m b e r o f p i n s f b v o l t a g e 0 9 5 : 9 5 m v
pam2803 document number: ds 36400 rev. 2 - 2 8 of 9 www.diodes.com december 2014 ? diodes incor porated pam2803 a product line of diodes incorporated package outline dimensions (all d imensions in mm . ) sot23 - 6
pam2803 document number: ds 36400 rev. 2 - 2 9 of 9 www.diodes.com december 2014 ? diodes incor porated pam2803 a product line of diodes incorporated important notice dio des incorporated makes no warranty of any kind, express or implied, with regards 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 ju risdiction). diodes incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein. diodes incorporated does no t assume any liability arising out of the application or use of this document or any product described herein; neither does diodes incorporated convey any license unde r its patent or trademark rights, nor the rights of others. any customer or user of this document or products 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 diod es incorporated website, harmless against all damages. diodes incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthor ized sales channel. should customers purchase or use diodes incorporated products for any unintended or unauthorized application, c ustomers shall indemnify and hold diodes incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees arising ou t 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 nam es and markings noted herein may also be covered by one or more united state s, international or foreign trademarks. this document is written in english but may be translated into multiple languages for reference. only the english version of this document is the final and determinative format released by diodes incorporated. lif e support diodes incorporated products are specifically not authorized for use as critical components in life support devices or system s 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 i n 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 expe cted to cause the failure of the life support device o r to affect its safety or effectiveness. customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support d evices or systems, and acknowledge and agree that they are solely responsible for all leg al, 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 b e 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. co pyright ? 201 4 , diodes incorporated www.diodes.com
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