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al1678 - 20b/10b /08b document number: ds 37637 rev. 1 - 2 1 of 13 www.diodes.com april 2015 ? diodes incorp orated al1678 - 2 0b/ 1 0b /08b new product universal, 500v buck led driver description the al1678 - 20b/10b /08b is a universal ac input (85 to 277 v ac ), high efficiency and high accuracy buck led driver. the al1678 - 20b/10b/08b topology provides accurate constant current over line and load regulation with tight tolerance 3% , operating at boundary conduction mode (bcm) to ease in emi/emc qualification and testing to meet the latest regulatory laws. the al1678 - 20b/10b/08b single buck stage system works with a single winding inductor and high voltage mosfet included, therefore, can use fewer external component s and create a low bill of material (bom) cost solution. the al1678 - 20b/10b/08b has rich protection features to enhance the system saf ety and reliability. it has thermal f ol d back function , which can reduce the output current when the drivers temperature is higher than the setting value. the al1678 - 20b/10b/08b is available in so - 7 package . features ? > 90% e fficiency ? valle y switching to achieve low switching loss ? universal 85 to 277 v ac input range ? internal mosfet up to 500v ? tight current sense tolerance: 3% ? low start - up current : 170 a ? low operation current: 100 a (static) ? single winding inductor ? internal protections ? unde r voltage lock out (uvlo) ? leading - edge blanking (leb) ? output o pen /short p rotection ? open - load and reload detection ? thermal fold - back function ? over t emperature p rotection (otp) ? so - 7 p ackage ? totally lead - free & fully rohs compliant (notes 1 & 2) ? halogen and a ntimony free. green device (note 3 ) pin assignments (top view) so - 7 applications ? retrofit led lamps ? high voltage dc - dc led driver ? general purpose constant current source note s: 1 . no purposely added lead. full y 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 diodes 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 antimony compounds. typical applications circuit o u t v c c r o v p g n d c s l c d r a i n 1 2 3 4 7 6 5 o u t + v c c c s g n d c 3 r 1 a c i n p u t f 1 d b 1 c 1 r o v p o u t r 2 l c d r a i n c 2 d 1 l 1 r 4 r 5 r 3 1 2 3 4 5 6 7 u 1 a l 1 6 7 8 - 2 0 b / 1 0 b / 0 8 b
al1678 - 20b/10b /08b document number: ds 37637 rev. 1 - 2 2 of 13 www.diodes.com april 2015 ? diodes incorp orated al1678 - 2 0b/ 1 0b /08b new product pin description s pin numbe r p in name function 1 out internal power mosfet s source 2 vcc power supply for the device 3 rovp setting the open voltage of the output 4 gnd ground 5 cs current sensing 6 lc line compensation pin 7 drain internal high voltage mosfet s drain functional block diagram v c c m a n a g e m e n t f a u l t m a n a g e m e n t u v l o v c c c l a m p o t p s t o p l e b c o n s t a n t c u r r e n t c o n t r o l m a x t o n l i m i t s t o p r s q t o f f d e t e c t i o n ( z c d ) o u t p u t o v p v c c o v p d r a i n v c c c s o u t g n d l c r o v p 3 5 2 7 1 6 4
al1678 - 20b/10b /08b document number: ds 37637 rev. 1 - 2 3 of 13 www.diodes.com april 2015 ? diodes incorp orated al1678 - 2 0b/ 1 0b /08b new product absolute maximum ratings (@ t a = + 25c, unless otherwise specified . ) ( note 4 ) symbol parameter rating unit v cc power supply voltage 18 v v drain voltage on drain pin al1678 - 20b 500 v a l1678 - 10b 500 v al1678 - 08 b 500 v i d continu ous drain current (t c = +25 o c) al1678 - 20b 2.0 a al1678 - 10b 1.0 a al1678 - 08 b 0.8 a v cs voltage on cs pin - 0.3 to 7 v v rovp voltage on r ovp pin - 0.3 to 7 v t j operating junction temperature - 40 to +150 oc t stg storage temperature - 65 to +150 oc t lead lead temperature (soldering, 10 sec) + 26 0 oc p d power dissipation and thermal characteristics (t a = +50 o c) 0.65 w ja thermal resistance (junction to ambient) 190 oc/w C ? esd ( human body model ) 2000 v esd ( machine model) 200 v note 4 : stresses greater than those listed under absolute maximum ratings may cause permanent damage to the device. these are stres s ratings only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating conditions is not implied. exposure to absolute maximum ratings for extended periods may affect device reliability. recommended operating conditions symbol parameter min max unit t a ambient temperatur e (note 5) - 40 +105 c note 5 : the device can operate normally at +125 c ambient temperature under the condition that the junction temperature is less than +150 c .
al1678 - 20b/10b /08b document number: ds 37637 rev. 1 - 2 4 of 13 www.diodes.com april 2015 ? diodes incorp orated al1678 - 2 0b/ 1 0b /08b new product electrical characteristics (@ t a = + 25c, unless otherwise specified .) symbol parameter conditions min typ max unit uvlo section v th (st) startup threshold C C 14.5 C v v opr(min) minimal operating voltage after turn on C 8.5 C v v cc_ c lamp v cc clamp voltage C C 16.2 C v standby current section i st start - up current v cc = v th (st) - 0.5v, before s tart u p C 170 C a i cc(opr) operating current static C 100 C a internal high voltage mosfet r ds(on) drain - source on state resistance al1678 - 20b C 5.4 6 ? al1678 - 10b C 10 12 al1678 - 08 b 16 20 i ds continuous drain - sou rce current al1678 - 20b C C 2.0 a al1678 - 10b C C 1 .0 al1678 - 08 b C C 0.8 v ds drain - source voltage al1678 - 20b 500 C C v al1678 - 10b 500 C C al1678 - 08 b 500 C C i dss drain - source leakage current v ds = 500v, v gs = 0, t c = +25 o c (al1678 - 2 0b ) C C 1 a v ds = 50 0v, v gs = 0, t c = +25 o c (al1678 - 1 0b ) C C 1 v ds = 50 0v, v gs = 0, t c = +25 o c (al1678 - 08 b ) C C 1 thermal foldback section and rovp section t reg overheating temperature regulation (note 6 ) C C +140 C o c v rovp reference voltage of r ovp p in C C 0.46 C v current sense section v cs - ref current sense reference C 0.388 0.400 0.412 v t on_min minimum t on C 400 C 700 ns t on_max maximum t on C C 35 C s t off _ max maximum t off C C 200 C s t off _ min minimum t off (note 6 ) C C 6 C s t d (h - l) delay to output (note 6 ) C 50 150 250 ns over temperature protection section C shutdown temperature (note s 6 & 7 ) C C +170 C c note s : 6. these parameters, although gua ranteed by design, are not 100% tested in production. 7. the device will latch when otp happens and the device wont operate constantly at this temperature.
al1678 - 20b/10b /08b document number: ds 37637 rev. 1 - 2 5 of 13 www.diodes.com april 2015 ? diodes incorp orated al1678 - 2 0b/ 1 0b /08b new product performance characteristics (note 8 ) start - up voltage vs. ambient temperature start - up current vs. ambient temperature minimal operating voltage vs. ambient temperature operating curre nt vs . ambient temperature v cs r eference vs. ambient temperature v rovp r eference vs. ambient temperature -40 -20 0 20 40 60 80 100 120 70 80 90 100 110 120 130 140 operating current ( ? a) ambient temperature ( o c) -40 -20 0 20 40 60 80 100 120 12.0 12.5 13.0 13.5 14.0 14.5 15.0 15.5 16.0 start-up voltage (v) ambient temperature ( o c) -40 -20 0 20 40 60 80 100 120 0.20 0.25 0.30 0.35 0.40 0.45 0.50 v cs reference (v) ambient temperature ( o c) -40 -20 0 20 40 60 80 100 120 0.30 0.35 0.40 0.45 0.50 0.55 0.60 v rovp reference (v) ambient temperature ( o c) -40 -20 0 20 40 60 80 100 120 120 130 140 150 160 170 180 start-up current ( ? a) ambient temperature ( o c) -40 -20 0 20 40 60 80 100 120 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0 minimal operating voltage (v) ambient temperature ( o c)
al1678 - 20b/10b /08b document number: ds 37637 rev. 1 - 2 6 of 13 www.diodes.com april 2015 ? diodes incorp orated al1678 - 2 0b/ 1 0b /08b new product performa nce characteristics (note 8 ) vcc c lamp v oltage vs. ambient temperature v cs reference vs. ambient temperature integrated 500v/1a mosfet soa ( note 9 ) i ntegrated 500v/ 2 a mosfet soa ( note 9 ) note s: 8. these electr ical characteristics are tested under dc condition. the ambient temperature is equal to the junction temperature of the devic e. 9. the mosfet soa curve is tested under the to - 251 package type. v ds , drain - to - source voltage (v) v ds , drain - to - source voltage (v) i d , drain current (a) i d , drain current (a) -40 -20 0 20 40 60 80 100 120 10 12 14 16 18 20 vcc clamp voltage (v) ambient temperature ( o c) -40 -20 0 20 40 60 80 100 120 140 160 180 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 v cs reference (v) ambient temperature ( o c)
al1678 - 20b/10b /08b document number: ds 37637 rev. 1 - 2 7 of 13 www.diodes.com april 2015 ? diodes incorp orated al1678 - 2 0b/ 1 0b /08b new product application information the al1678 - 20b/10b/08b is designed for single induct or buck application, it is an extremely low b om cost solution widely used in non - isolate situation. it operates as boundary conduct ion mode (bcm) which can get a good emi performance. the device internally integrates a 500v high voltage mosfet . the al1678 - 20b/10b/08b adopts a novel method to detect the t off time and reali ze an extremely low operation current, so the device does not need the auxiliary winding for v cc supply and detects the t off time. it also has a good constant current control which can guarantee the system current accuracy. fi gure 1. typical application circuit design p arameters setting the c urrent s ense r esistor r5 the al1678 - 20b/10b/08b uses peak current control method to obtain constant current control and senses the peak current of the induct or cycle by cy cle. the sample value is compared with the internal 0.4v reference, when the sample value is up to 0.4v, the ic control the i nternal mosfet turned off. so the peak current of the inductance is where, v cs_ref is the reference of the current sense, and the typical value is 0.4 v. r5 is the current sense resistor. in no pf buck topology, the system operates at boundary conduct mode, so the output current is so, the current sense resistor r5 is deter mined: inductance selection (l 1) the al1678 - 20b/10b/08b controls the system operat ing at boundary conduction mode , and t he systems operating frequency do es not keep constant because of the fluctuation of the bus voltage, set the minimum switching frequency f min a t the maximum bus voltage , a nd buck inductance value l 1 is : o u t + v c c c s g n d c 3 r 1 a c i n p u t f 1 d b 1 c 1 r o v p o u t r 2 l c d r a i n c 2 d 1 l 1 r 4 r 5 r 3 1 2 3 4 5 6 7 u 1 a l 1 6 7 8 - 2 0 b / 1 0 b / 0 8 b 5 _ r v i ref cs peak ? peak mean o i i ? ? 2 1 _ mean o ref cs i v r _ _ 2 1 5 ? ?
al1678 - 20b/10b /08b document number: ds 37637 rev. 1 - 2 8 of 13 www.diodes.com april 2015 ? diodes incorp orated al1678 - 2 0b/ 1 0b /08b new product application information (cont.) where, v o is the output voltage . v in_rms is the rms value of the input voltage . according to the faradays law of induction, the winding number of the inductance can be got: where , a e is the core effective area . b m is the maximum magnetic flux density . the al1678 - 20b/10b/08b has designed the minimum t on time and maximum t on time, the t on_min is about 700ns and the t on_max time is about 35s. in buck topology we can get the equation v in_rms - v o = l*i peak /t on . if the inductance is very small, it leads to the t on becoming smaller, when the sys tems t on is smaller than t on_min , the device cant detect the peak current of the system leading to wrong output current. while if the inductance is very large, it leads to the t on becoming longer, when the systems t on is longer than the t on_max , the sys tem will trigger ovp, and the led will flicker. so the suitable value of the inductance is very important. the al1678 - 20b/10b/08b has also designed the minimum t off time and the maximum t off time, the t off_min time is about 6s and t off_max time is about 200s. in buck topology we can get the equation v o = l*i peak /t off . if the inductance is very small, it leads to the t off becoming much smaller, when the systems t off is smaller than t off_min , the system will enter dcm mode, and the output cu rrent will be wrong. while if the inductance is very large, it leads to the t off becoming much longer, when the systems t off is longer than the t off_max , the system will enter ccm mode, and the output current will also be wrong. so the suitable value of t he inductance is very important. consider these parameters, two examples of the typical application inductance is recommended as below: system spec inductance value system frequency t on_ min t off 60v/150ma (85 to 2 77 v ac ) 2.3mh 60khz (230v ac ) 2.5s (265v ac ) 11.5s 42v/100ma (85 to 2 77 v ac ) 2.5mh 62khz (230v ac ) 1.7s (265v ac ) 12.1s fault protection setting output open voltage the al1678 - 20b/10b/08b has output open voltage protection, and the output voltage is controlled when the led is op en, which can prevent the output voltage increasing to a very high value. this feature can help the system designer to select a smaller volume capacito r. the output voltage is set by the external resistor r3 shown in figure 1. when the led is open, the t o ff time can be calculated as where, m in _ _ _ 2 5 ) 2 ( 1 f v v v r v v l rms in ref cs o o rms in ? ? ? ? ? ? 5 1 1 _ 1 r b a v l b a i l n m e ref cs m e peak l ? ? ? ? ? ? ? 5 r 1 _ ? ? ? ovp ref cs off v v l t
al1678 - 20b/10b /08b document number: ds 37637 rev. 1 - 2 9 of 13 www.diodes.com april 2015 ? diodes incorp orated al1678 - 2 0b/ 1 0b /08b new product application information (cont.) v ovp is the output open voltage. when the led is open, the output voltage is set by r3, and r3 is where , v rovp_ref is the inte rnal rovp pin 0.46 vs reference . c ref is the internal 6 p f capacitor . output short protection when the led is short ed, the device cant detect the demagnetization time, the device controls the system operation at 5ks low frequency. thermal f old b ack fun ction al1678 - 20b/10b/08b has thermal fold back function , it adopts self - adaptive control method which can prevent the system breaking down caused by high temperature. the overheating temperature is set at + 140 c , when the temperature of the i c is higher than +140 c the device will decrease the reference of the cs linearly till otp happens. by this way, the device can control the systems output power at high ambient temperature, so the quantity of heat of the system can be controlled and tempe rature of the system is controlled, so the safety of the system at high temperature is got enhanced. over temperature protection the al1678 - 20b/10b/08b has otp protection function . when the temperature is increased to + 170c, the ic will tri gger over temperature protection which leads to a latch operating mod e. when otp happens, the system can restart under the condition that the systems ac source supply is powered off first. recommended a pplications the al1678 - 20b/10b/08b int egrates different mosfet to adapt different wattage application. and the output current is limited by the internal integrated mosfet and the so - 7 packages heat dissipation capability. and the minimum output voltage is limited by the leb time, the minimum output voltage is recommended to 15 v . so the recommended application is given below: device output power coverage maximum output current (n ote 10) minimum output voltage al1678 - 20b 240ma 10w 1 1 n ote 10 : the higher output current is possible with extra power dissipation solution. 5 40 1 40 3 _ _ _ r v c l v v c t v r ovp ref ref rovp ref cs ref off ref rovp ? ? ? ? ? ? ? ? ?
al1678 - 20b/10b /08b document number: ds 37637 rev. 1 - 2 10 of 13 www.diodes.com april 2015 ? diodes incorp orated al1678 - 2 0b/ 1 0b /08b new product ordering information part number package c ode package 13 tape and reel quantity part number suffix al1678 - 20bs7 - 13 s 7 s o - 7 40 00 /tape & reel - 13 al1678 - 10bs7 - 13 s 7 s o - 7 40 00 /tape & reel - 13 al1678 - 0 8 bs7 - 13 (n ote 11) s 7 s o - 7 40 00/tape & reel - 13 n ote 11 : the al1678 - 08bs7 - 13 is still unde r development and not orderable . mark ing informatio n a l 1 6 7 8 - x x x x x - 1 3 p a c k a g e c u r r e n t o p t i o n s 7 : s o - 7 1 0 : 1 . 0 a 2 0 : 2 . 0 a p r o d u c t n a m e p a c k i n g 1 3 : 1 3 " t a p e & r e e l m o s f e t v o l t a g e b : 5 0 0 v 0 8 : 0 . 8 a 1 6 7 8 - z z z ( t o p v i e w ) y y w w x x p a r t n u m b e r 1 6 7 8 - 2 0 b f o r 2 . 0 a / 5 0 0 v 1 6 7 8 - 1 0 b f o r 1 . 0 a / 5 0 0 v 1 6 7 8 - 0 8 b f o r 0 . 8 a / 5 0 0 v l o g o w w : w e e k : 0 1 ~ 5 2 ; 5 2 y y : y e a r : 1 5 , 1 6 , 1 7 ~ x x : i n t e r n a l c o d e 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
al1678 - 20b/10b /08b document number: ds 37637 rev. 1 - 2 11 of 13 www.diodes.com april 2015 ? diodes incorp orated al1678 - 2 0b/ 1 0b /08b new product package outline dimensions (all d imensions in mm (inch) . ) (1) package type: so - 7 3 . 8 0 0 ( 0 . 1 5 0 ) 4 . 0 0 0 ( 0 . 1 5 7 ) 1 . 2 7 0 ( 0 . 0 5 0 ) t y p 4 . 7 0 0 ( 0 . 1 8 5 ) 5 . 1 0 0 ( 0 . 2 0 1 ) 0 . 3 3 0 ( 0 . 0 1 3 ) 0 . 5 1 0 ( 0 . 0 2 0 ) 0 . 1 5 0 ( 0 . 0 0 6 ) 0 . 2 5 0 ( 0 . 0 1 0 ) 0 . 0 8 0 ( 0 . 0 0 3 ) 0 . 2 5 0 ( 0 . 0 1 0 ) 1 . 3 5 0 ( 0 . 0 5 3 ) 1 . 7 5 0 ( 0 . 0 6 9 ) 0 . 4 5 0 ( 0 . 0 1 7 ) 0 . 8 0 0 ( 0 . 0 3 1 ) 8 0 5 . 8 0 0 ( 0 . 2 2 8 ) 6 . 2 0 0 ( 0 . 2 4 4 ) 2 . 5 4 ( 0 . 1 0 0 ) t y p 1 . 2 5 0 ( 0 . 0 4 9 ) 1 . 5 0 0 ( 0 . 0 5 9 ) 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 . o p t i o n 2 4 5 0 . 3 5 0 ( 0 . 0 1 4 ) t y p o p t i o n 1
al1678 - 20b/10b /08b document number: ds 37637 rev. 1 - 2 12 of 13 www.diodes.com april 2015 ? diodes incorp orated al1678 - 2 0b/ 1 0b /08b new product suggested pad layout (1) package type: so - 7 dimensions z (mm)/(inch) g (mm)/(inch) x (mm)/(inch) y (mm)/(inch) e (mm)/(inch) e 1 (mm)/(inch) value 6.900/0.272 3.900/0.154 0.650/0.026 1.500/0.059 1.270/0.050 2.54 0/0. 1 00 z g e 1 e x y
al1678 - 20b/10b /08b document number: ds 37637 rev. 1 - 2 13 of 13 www.diodes.com april 2015 ? diodes incorp orated al1678 - 2 0b/ 1 0b /08b 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 (a nd their equivalents under the laws of any jurisdiction). 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 not 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 ri ghts 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 incorporat ed 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, customers 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 injur y 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 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 lif e 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 d evices or systems, and acknowledge and agree that they are solely respo nsible for all legal, regulatory and safety - related require ments 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. furth er, 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 ? 201 5 , diodes incorporated www. diodes.com

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