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AL8821 document number: ds 37671 rev. 1 - 2 1 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product 40v, 2a boost led driver description the AL8821 is a b oost converter that delivers an accurate constant current for mr16 and similar led lamps. with proprietary control scheme, the led driver is compatible with many commonly used electroni c transformers and provides designs with high power factor (pf) and low total harmonic distortion (thd) for these applications. the operation frequency is up to 1mhz that allows the use of small size inductor . with the package of so - 8ep , the AL8821 ha s sma ll thermal resistance and can be used for wide range of output power. the driver can be used for dimmable mr16 application and can be compatible with leading - edge dimmer and trailing - edge dimmer. features ? wide input voltage range: 5v to 36 v ? internal 40v ndmos switch es ? continuous conduction mode (ccm) operation ? up to 1mhz switching frequency ? high pf > 0.9 and l ow thd < 30% and low ripple < 20% ? compatible with leading - edge dimmer and trailing - edge dimmer ? internal protections ? under voltage lock out (uvlo) ? o utput open ? over temperature protection (otp) ? pb - free so - 8ep ? totally lead - free & fully rohs compliant (notes 1 & 2) ? halogen and antimony free. green device (note 3 ) pin assignments (top view) so - 8ep applications ? non - di mmable mr16 lamps ? dimmable mr16 lamps ? general illumination lamps note s: 1 . no purposely added lead. fully eu directive 2002/95/ec (rohs) & 2011/65/eu (rohs 2) compliant. 2. see http://www.diodes.com/quality/lead_free.html for more information about diod es incorporateds definitions of hal ogen - and antimony - free, "green" and lead - f ree . 3. halogen - and antimony - free "green products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total br + cl) and <1000ppm ant imony compounds. typical applications circuit d 2 d 1 d 3 d 4 d 5 r s e t r h y s c o c 3 s w c s v c c c o m p v i n ( e x p o s e d p a d ) l c 4 v a c a l 8 8 2 1 f b r f b 1 2 3 4 8 7 6 5 s w c s f b c o m p n c v c c v i n n c e p
AL8821 document number: ds 37671 rev. 1 - 2 2 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product pin description s pin number pin name function 1 sw integrated mos drain 2 cs input current sense pin 3 fb led output current feedback pin 4 c o mp control loop compensation p in 5 nc not connected 6 v in ic i nput v oltage, a dding from boost output v oltage 7 vcc supply voltage for internal circuit 8 nc not connected 9 exposed pad connected t o g round functional block diagram v i n u v l o c h i p _ e n v b g e x p o s e d p a d e a f b v b g c o m p c s 1 c s v c s 1 s w c o m p a r a t o r o v p v f b o v p o t p o t p b a n d g a p v b g v c c v r e f l o g i c d r i v e r v c c i n t e r n a l r e g u l a t o r v c c v i n i h y s i h y s p w m 1 p w m 1 2 3 6 7 1 4 9
AL8821 document number: ds 37671 rev. 1 - 2 3 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product absolute maximum ratings (@ t a = + 25c, unless otherwise specified . note 4 ) symbol parameter rating unit v in v in pin voltage - 0.3 to 40 v v sw sw pin voltage - 0.3 to 40 v v comp comp pin voltage - 0.3 to 6 v v cs cs pin voltage - 0.3 to 6 v v fb fb pin voltage - 0. 3 to 6 v v cc vcc pin voltage - 0.3 to 6 v t j operating junction temperature + 1 50 oc t stg storage temperature - 65 to + 1 5 0 oc ja thermal resistance ( junction t o ambient ) (note 5) 66 c/w t lead lead temperature (soldering, 10sec) +300 oc C esd ( machine model) 200 v C esd ( human body model) 2000 v note s : 4. stresses greater than those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only and functional operation of the device at these or an y other condition s beyond those indicated under recommended operating conditions is not implied. exposure to absolute maximum ratings for extended periods may affect device reliability. 5. device mounted on fr - 4 pcb (51mm x 51mm ) 2oz copper, minimum re commended pad layout on top layer and thermal vias to bottom layer ground plane. for better thermal performance, larger copper pad for heat - sink is needed. recommended operating conditions symbol parameter min max unit v in vin pin voltage 5 36 v t a am bient temperature - 40 + 105 c electrical characteristics (@ t a = + 25c, unless otherwise specified .) symbol parameters conditions min typ max unit input supply v in vin pin voltage C 5 C 36 v i q quiescent current no s witching C 1 C ma v uvlo under - vo ltage lockout voltage v in rising C 4.2 C v v hys uvlo hysteresis C C 500 C mv vcc regulator v cc v cc pin voltage C 4.5 5 5.5 v C source current capability v cc = 5v 10 C C ma C load regulation C C 4 C %
AL8821 document number: ds 37671 rev. 1 - 2 4 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product electrical characteristics ( cont. @ t a = + 25c, un less otherwise specified . ) symbol parameters conditions min typ max unit integrated nmos_boost v ds mos voltage s tress (note 6) C C C ds mos current s tress (note 6) C C C dson mos r dson C C C ? compensation and soft start (comp pin) gea error amplifier trans - conductance C C C o - h sourcing current v comp = 0.5v C C o - l sinking current v comp = 4.5v C C fb fb pin voltage C C C hysteresis comp e titor v cs _ min bo ost sense voltage low level v comp = 0v C C hys hys teresis c urrent C over - temperature protection t otsd thermal shutdown (note 6) C C C hys thermal shutdown hysteresis (note 6) C C C note 6: these parameters, altho ugh guaranteed by design, are not 100% tested in production.
AL8821 document number: ds 37671 rev. 1 - 2 5 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product performance characteristics quiescent current vs. vin pin voltage quiescent current vs. ambient temperature v cc pin voltage vs. vin pin voltage v cc pin voltage vs. ambient temperature fb pi n voltage vs. vin pin voltage fb pin voltage vs. ambient temperature -45 -30 -15 0 15 30 45 60 75 90 105 0.6 0.8 1.0 1.2 1.4 quiescent current (ma) ambient temperature ( o c) v in = 12v 4 8 12 16 20 24 28 32 36 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 vcc pin voltage (v) vin pin voltage (v) 4 8 12 16 20 24 28 32 36 0.40 0.42 0.44 0.46 0.48 0.50 fb pin voltage (v) vin pin voltage (v) -45 -30 -15 0 15 30 45 60 75 90 105 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5 vcc pin voltage (v) ambient temperature ( o c) v in = 12v 4 8 12 16 20 24 28 32 36 0.6 0.7 0.8 0.9 1.0 1.1 1.2 quiescent current (ma) vin pin voltage (v) -45 -30 -15 0 15 30 45 60 75 90 105 0.40 0.42 0.44 0.46 0.48 0.50 fb pin voltage (v) ambient temperature ( o c) v in = 12v
AL8821 document number: ds 37671 rev. 1 - 2 6 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product performance characteristics (cont.) boost sense voltage low level vs. boost sense voltage low level vs. vin pin voltage ambient temperature hys teresis c urrent vs. vin pin voltage hys teresis c urrent vs. ambient temperature -45 -30 -15 0 15 30 45 60 75 90 105 102 104 106 108 110 112 114 hysteresis current ( ? a) ambient temperature ( o c) v in = 12v 4 8 12 16 20 24 28 32 36 -90 -88 -86 -84 -82 -80 boost sense voltage low level (mv) vin pin voltage (v) 4 8 12 16 20 24 28 32 36 104 106 108 110 112 114 116 hysteresis current ( ? a) vin pin voltage (v) -45 -30 -15 0 15 30 45 60 75 90 105 -90 -88 -86 -84 -82 -80 boost sense voltage low level (mv) ambient temperature ( o c) v in = 12v
AL8821 document number: ds 37671 rev. 1 - 2 7 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product application information al882 1 operation the AL8821 is a boost convert er that delivers an accurate constant current for driving leds. with hysteretic control scheme, the led driver is compatible with most of commonly used electronic transformers. the driver can be compatible with leading - edge dimmer and trailing - edge dimmer . figure 1 . typical application circuit led current control the led current is controlled by the resistor r fb in f igure 1. connected between fb pin and ground, the nominal average output current in the led(s) is defined as: r set and r hys setting the boost converter of the al882 1 operates at c ontinuous c onduction mode and is base d on hysteresis schematic which has lower threshold and upper threshold. refer to figure 2 depictin g the inductor current waveform . figure 2 . inductor current when switch sw is turned on, the inductor current flows through r set and ramps up linearly. the rising current produces a voltage ramp across r set . when the voltage across r set reaches t he upper threshold, switch sw is turned off. the inductor current continues to flow through r set but decays. the decaying current produces a falling voltage at r set . when the voltage across r set falls to the lower threshold, switch sw is turned on again. t he lower threshold voltage v lt depends on the voltage v comp at comp pin that varies with the input voltage and output load. t he equation is shown as below. i l i l ( a v e ) i l ( v a l ) t i m e i l t o n t o f f p e a k o r u p p e r t h r e s h o l d v a l l e y o r l o w e r t h r e s h o l d i l ( p e a k ) d 2 d 1 d 3 d 4 d 5 r s e t r h y s c o c 3 s w c s v c c c o m p v i n ( e x p o s e d p a d ) l c 4 v a c a l 8 8 2 1 f b r f b 0.444 led fb r ?
AL8821 document number: ds 37671 rev. 1 - 2 8 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product application information (cont.) the range of v comp is from 0v to 5v. t he upper threshold depends on the lower threshold and the hysteresis value. the hysteresis value is set by external resister r hys . it is defined as below. according to the operation principle , the peak to peak current ? i l and the valley current i l(val) can be obtained by the below equations. where : ? i l is the peak to peak current of inductor . i l(val) is the valley current of inductor. from the f igure 2, the relationship b etween i l ( peak) , i l(val) , i l(ave) and ? i l can be obtained as below. where: i l (peak) is the peak current of inductor . i l(ave) is the average current of inductor. as we know the average current i l(ave) de pend s on the output power , rated input voltage v in1 of step - up converter and total efficiency . so the average current i l(ave) can be obtained by the f o llow ing equation. where: v led is the voltage in leds. set ratio of ? i l to i l ( peak) as k. set lt val l r v i ? ) ( l val l peak l i i i ? ? ? ) ( ) ( 1 ) ( ) 444 . 0 ( in led led ave l v i v i ? ? ? ? ? set hys l r v i ? ? l val l ave l i i i ? ? ? ? 2 1 ) ( ) ( ( 1.5) 0.6 1.4 ,1.5 5 16 88 , 0 1.5 comp comp lt comp v mv v v v v mv v v v ? ? ? ? ?? ? ? ? ? ?? ? 100 hys hys v r a ? ??
AL8821 document number: ds 37671 rev. 1 - 2 9 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product application information (cont.) r set and r hys can be obtained from above equations: w hen the value of k, and v comp are provided , the value of resister r set an d r hys can be calculated according to these above equations. in order to get appropriate efficiency and electronic transformer (et) compatibility, generally k is set between 0.4 and 0.8. due to t he range of v comp is from 0v to 5v , in order to get output vo ltage regulation, generally v comp is set as 3v at rated input voltage. inductor selection because of the using of the hysteretic control scheme, the switching frequency in a boost configuration can be adjusted in ac cordance to the value of the inductor b eing us ed . the value of the inductor can be determined on the desired switching frequency by using the following equation: where: l is the coil inductance . r l is the coil resistance . r dson is the switch sw resistance . v in 1 is the rated input voltage . v f is the diode forward voltage . f sw is the desired switching frequency . g enerally 5 00khz to 800khz switching frequency is suggested. l ow switching frequency can decrease the switching loss but need to choose higher inductor val ues that will result in larger size in order to meet the saturation current. for example the relation ship between switching frequency and inductor value is shown as below t able 1 in the same application system. considering these factors, 5 00khz switching f requency is recommend in typical application. inductance value of l @ vac = 12vac, v in = 22v v led = 28v, i led = 180 ma operation frequency o f sw a t peak voltage of vac 10 h 840 khz 15 h 800 khz 22 h 680 khz 33 h 465khz table 1 ) ( peak l l i i k ? ? 4 1 2 ( 0.444) 10 = (2 ) led led set hys in v i k r r vk ? ? ? ? ? ? ? ? ? ? sw ave l dson l set f led l ave l set l f in led ave l dson l set in f i r r r v v i i r r v v v i r r r v l ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ] ) 2 2 ( 444 . 0 [ ] ) ( 444 . 0 [ ] ) ( [ ) ( ) ( 1 ) ( 1 3 1 3 1 (( 1.5) 0.6 1.4) (2 ) 10 1.5 5 32 ( 0.444) -k = 44 (2 ) 10 , 0 1.5 ( 0.444) -k comp in comp led led set in comp led led v k v v v v vi r kv v v v vi ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? ? ? ? ? ? ? ? ? ?? ? ? ? ? ? 1 1
AL8821 document number: ds 37671 rev. 1 - 2 10 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product application information (cont.) v in ovp protection al882 1 has an internal over voltage protection to protect ic from excessive input voltage. when the voltage applied at v in pin exceeds 39v, it will turn off the power switch sw . the power switch sw wil l be turn ed on again once the voltage at v in drops below 3 4v . v cc regulator the v cc pin requires a capacitor c3 for stable operation and to store the charge for the large gate switching currents. choose a 10v rated low esr, x7r or x5r, ceramic capacitor for best performance. a 4 .7 f capacitor will be adequate for many applications. place the capacitor close to the ic to minimize the trace length to the v cc pin and to the ic ground. an internal current limit on the v cc output protects the excessive on - chip power dissipation. the v cc pin has set the output to 5v (typ.) to protect the internal fets from excessive power dissipation caused by not being fully enhanced. if the v cc pin is used to drive extra circuits beside the al882 1 , the extra loads s hould be limited to less than 8 ma. output c apacitor c o the capacitor c o is used to hold the bus voltage and reduce the ripple of led current when the electronic transformer has no output . for most applications, it is recommended to use an aluminum electrolytic capacitor with greater than 220 f capacitance. compensation c apacitor c4 in applications powered by electronic transformer, the input voltage can change roughly in one cycle of ac power frequency. a 1 f ceramic capacitor c4 connected from comp pin to ground help to stabilize the con trol loop of the regulator. diode s election for maximum efficiency and performance, the rectifier s (d5) should be fast low ca pacitance schottky diodes wi th low reverse leakage at maximum operating voltage and temperature. with its low power dissipation, the schottky diode outperforms other silicon diodes and increases overall efficiency. over temperature protection a over temperature protection feature is to protect the al882 1 from excessive heat damage . when the junction temperature exceeds + 160 oc , the internal fet will be turn ed off. when junction temperature drops below + 1 2 0 oc , ic will turn on both fets and return to normal operation.
AL8821 document number: ds 37671 rev. 1 - 2 11 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product ordering information part number package c ode package 13 tape and reel quantit y part number suffix al882 1 sp - 13 sp so - 8ep 2500/tape & reel - 13 marking informatio n a l 8 8 2 1 ( t o p v i e w ) y y w w x x e l o g o w w : w e e k : 0 1 ~ 5 2 ; 5 2 y y : y e a r : 0 8 , 0 9 , 1 0 ~ x x : i n t e r n a l c o d e 8 7 6 5 1 2 3 4 r e p r e s e n t s 5 2 a n d 5 3 w e e k e : s o - 8 e p p a r t n u m b e r a l 8 8 2 1 x x - x x p a c k i n g p a c k a g e 1 3 : 1 3 " t a p e & r e e l s p : s o - 8 e p
AL8821 document number: ds 37671 rev. 1 - 2 12 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product package outline dimensions (all d imensions in mm (inch) . ) (1) package type: so - 8ep 8 5 . 8 0 0 ( 0 . 2 2 8 ) 6 . 2 0 0 ( 0 . 2 4 4 ) 1 . 2 7 0 ( 0 . 0 5 0 ) 0 . 4 0 0 ( 0 . 0 1 6 ) 3 . 8 0 0 ( 0 . 1 5 0 ) 4 . 0 0 0 ( 0 . 1 5 7 ) 0 . 5 1 0 ( 0 . 0 2 0 ) 0 . 0 5 0 ( 0 . 0 0 2 ) 0 . 1 5 0 ( 0 . 0 0 6 ) 4 . 7 0 0 ( 0 . 1 8 5 ) 1 . 2 7 0 ( 0 . 0 5 0 ) t y p 0 0 . 2 5 0 ( 0 . 0 1 0 ) 0 . 1 5 0 ( 0 . 0 0 6 ) 1 . 3 5 0 ( 0 . 0 5 3 ) 1 . 5 5 0 ( 0 . 0 6 1 ) 2 . 1 1 0 ( 0 . 0 8 3 ) 2 . 7 1 0 ( 0 . 1 0 7 ) 2 . 7 5 0 ( 0 . 1 0 8 ) 3 . 4 0 2 ( 0 . 1 3 4 ) 5 . 1 0 0 ( 0 . 2 0 1 ) n o t e : e j e c t h o l e , o r i e n t e d h o l e a n d m o l d m a r k i s o p t i o n a l . 0 . 3 0 0 ( 0 . 0 1 2 )
AL8821 document number: ds 37671 rev. 1 - 2 13 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product suggested pad layout (1) package type: so - 8ep dimensions z (mm)/(inch) g (mm)/(inch) x (mm)/(inch) y (mm)/(inch) x1 (mm)/(inch) y1 (mm)/(inch) e (mm)/(inch) value 6.900/0.272 3.900/0.154 0.650/0.026 1.500/0.059 3.600/0.142 2.700/0.106 1.270/0.050 g e x x 1 y y 1 z
AL8821 document number: ds 37671 rev. 1 - 2 14 of 14 www.diodes.com january 2015 ? diodes incorporated AL8821 new product important notice diodes 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 jurisdiction). diodes incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other change s without further notice to this document and any product described herein. diodes incorporated does not assume any liability a rising out of the application or use of this document or any product described herein; neither does diodes incorporated convey an y license under its patent or trademark rights, nor the rights of others. any customer or user of this document or products described herein in such appli cations shall assume all risks of such use and will agree to hold diodes incorporated and all the com panies 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 unauthor ized sales channel. should c ustomers purchase or use diodes incorporated products for any unintended or unauthorized application, customers shall indemni fy and hold diodes incorporated and its representatives harmless against all claims, damages, expenses, and attorney fees arising o ut 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 states, 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. life 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 th e 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 expe cted to cause the failure of the life support device or to affect its safety or effectiveness. customers represent that th ey have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety - related requirements concerning their produ cts 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 ind emnify 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 ? 201 5 , diodes incorporated www.diodes.com

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