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AL8812 document number: ds37099 rev. 1 - 2 1 of 11 www.diodes.com march 2014 ? diodes incorporated a l8812 boost/buck dc-dc converter for dimmable mr16 led lamps description the AL8812 is a monolithic control circuit containing the primary functions required for dc-to-dc c onverters with mosfet in one package. these devices consist of an internal temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. additionally a 60v, 3.6a mosfet is integrated for reduced bom cost and size. this series is specifically designed for buck and boost applications with a minimum number of external components. features ? operation from 3.0v to 20v input ? integrated 60v, 3.6a mosfet ? low standby current ? current limiting ? output voltage adjustable ? frequency operation to 100 khz ? precision 2% reference ? totally lead-free & fully rohs compliant (notes 1 & 2) ? halogen and antimony free. ?green? device (note 3) pin assignments applications ? low voltage led lighting such as mr-16 ? general purpose dc-dc converter notes: 1. no purposely added lead. fully eu directiv e 2002/95/ec (rohs) & 2011/6 5/eu (rohs 2) compliant. 2. see http://www.diodes.com/quality/lead_free.html for more in formation about diodes incorporated?s definitions of halogen- a nd antimony-free, "green" and lead-free. 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 dimmable mr-16 led driver system diagram (for detailed schematic please contac t your diodes sales representative) nc gate input vcc sense drive sw/c sw/e gnd timing source drain u-dfn6040-12 2 3 4 5 6 7 8 9 10 11 12 1
AL8812 document number: ds37099 rev. 1 - 2 2 of 11 www.diodes.com march 2014 ? diodes incorporated a l8812 pin descriptions pin name pin number (u-dfn6040-12) function nc 1 no connection gate 2 gate connection of internal mosfet. input 3 feedback pin for inverting input of internal comparator vcc 4 supply voltage pin sense 5 no connection. drive 6 current drive collector: normally connected to v cc directly or via a resistor. sw/c 7 internal switch transistor collector sw/e 8 internal switch transistor emitter gnd 9 ground connection timing 10 timing capacitor to control the switching frequency. source 11 source connecton of internal mosfet drain 12 drain connection of internal mosfet exposed pad1 exposed pad of mosfet drain exposed pad2 exposed pad of AL8812 and connect to pcb ground functional diagram 1.25v reference regulato r ipk oscillato r c t r s q q2 q1 100 comparato r + _ gnd timing sw/e sw/c d rive sense vcc input ? g a te d rain s ource 2 3 4 5 6 7 8 9 10 12 11
AL8812 document number: ds37099 rev. 1 - 2 3 of 11 www.diodes.com march 2014 ? diodes incorporated a l8812 absolute maximum ratings (@t a = +25c, unless otherwise specified.) symbol parameter value unit v cc power supply voltage 20 v v ir comparator input voltage range -0.3 to +36 v sw/c switch collector voltage 36 v sw/e switch emitter voltage (v pin 1 = 40v) 36 v v ce (switch) switch collector to emitter voltage 36 v drive driver collector voltage 36 v i c (driver) driver collector current (note 4) 100 ma i sw switch current 1.6 a v ds maximum mosfet drain-source voltage 60 v v gs maximum mosfet gate-source voltage +/-20 v i source maximum continuous source (body diode) current 3.7 a p d continuous power dissipation (t a = +25 c) (u-dfn6040-12 (derate 10mw/ c above +25 c) 1000 mw ja junction-to-ambient thermal resistance 47.31 c/w jc junction-to-case thermal resistance 6.42 c/w t mj maximum junction temperature +150 c t op operating junction temperature range 0 to +105 c t stg storage temperature range -65 to +150 c esd hbm human body model esd protection 250 v esd mm machine model esd protection 100 v note: 4. maximum package power dissipation limits must be observed. electrical characteristics (@t a = +25c, unless otherwise specified.) symbol characteristics min typ max unit oscillator f osc frequency (v pin 5 = 0v, c t = 1.0nf, t a = +25 c) 24 33 42 khz i chg charge current (v cc = 5.0v to 40v, t a = +25 c) 24 30 42 a i dischg discharge current (v cc = 5.0v to 40v, t a = +25 c) 140 200 260 a i dischg / i chg discharge to charge current ratio (pin 7 to v cc , t a = +25 c) 5.2 6.5 7.5 ? v ipk (sense) current limit sense voltage (i chg = i dischg , t a = +25 c) 300 400 450 mv output switch (note 5) v ce (sat) saturation voltage, darlington connection (i sw = 1.0a, pins 1,8 connected) ? 1.0 1.3 v v ce (sat) saturation voltage, darlington connection (i sw = 1.0a, id = 50ma, forced ? 20) ? 0.45 0.7 v h fe dc current gain (i sw = 1.0a, v ce = 5.0v, t a = +25 c) 50 75 ? ? i c (off) collector off-state current (v ce = 40v) - 0.01 100 a output mosfet v gs(th) mosfet gate threshold voltage 1 ? 2.2 v v fd mosfet diodes forward voltage ? .85 .95 v r ds(on) drain-source on-resistance (vgs = 10v, id = 2.5a) drain-source on-resistance (vgs = 4.5v, id = 2a) ? ? 120 180 m ? m ? comparator v th threshold voltage t a = +25 c t a = 0 o c to +70 o c ? ? ? v ? 1.225 1.25 1.275 ? ? 1.21 ? 1.29 ? reg line threshold voltage line regulation (v cc = 3.0v to 40v) ? 1.4 6.0 mv total device i cc supply current (v cc = 5.0v to 40v, c t =1.0 n f, pin 7 = v cc , v pin 5 > v th pin 2 = gnd, remaining pins open) ? ? 3.5 ma note: 5. low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient temperature as possible.
AL8812 document number: ds37099 rev. 1 - 2 4 of 11 www.diodes.com march 2014 ? diodes incorporated a l8812 performance characteristics figure 1. vce(sat) versus le 0.6 0.8 1 1.2 1.4 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 ie, emitter current (a) vce(sat), saturation voltage (v) 1.24 1.245 1.25 1.255 1.26 0 10203040 5060708090100 temperature ( o c) reference voltage (v) figure 2. reference voltage versus temp. figure 4. standby supply current versus supply voltage 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0 5 10 15 20 25 30 35 40 vcc, supply voltage (v) icc, supply current (ma) 1.4 1.45 1.5 1.55 1.6 1.65 1.7 1.75 1.8 100 300 500 700 900 1100 1300 1500 i e (ma) v ce ( sat), (v) figure 5. emitter follower configuration output saturation voltage vs. emitter current 0.1 1 10 100 1000 0.01 0.1 1 10 c t , oscillator timing capacitor ( nf) t on-off , output switch on-off time(us) figure 6.output switch on-off time versus oscillator timing capacitor v cc = 5.0v pin 7 = v cc pin 5 = gnd t a = 25 o c t on t off vcc=2~10v pin1,7,8=vcc pin3,5=gnd t a =25 o c pin2=5 figure 3. current limit sense voltage versus temperature 320 340 360 380 400 420 440 0 102030 40 50 6070 8090100 temperature ( o c) current sense voltage (mv) 10w
AL8812 document number: ds37099 rev. 1 - 2 5 of 11 www.diodes.com march 2014 ? diodes incorporated a l8812 0. 1 1 10 0.1 1 10 0.1 1 10 0.1 1 10 23 45 0.1 1 10 -50 0 50 100 150 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 110 0.1 1 0.4 0.6 0.8 1.0 1.2 0.1 1 10 4v 10v 5v 3.5v 2.5v output characteristics t = 25c 3v v gs i d drain current (a) v ds drain-source voltage (v) 2v 2.5v 4v 10v 5v 3v output characteris tics t = 150c v gs 3.5v i d drain current (a) v ds dr ain- so urc e v oltag e ( v) typical transfer characte ristics v ds = 10v t = 25c t = 150c i d drain current (a) v gs g a te -s o urce v o ltag e (v ) normalised curves v temperature r ds(on ) v gs = 10v i d = 2.5a v gs ( th) v gs = v ds i d = 250ua normalised r ds (on ) and v gs(th) tj junction temperature (c) 4.5v 4v 5v 3.5v on-resistance v drain current t = 25c 3v 10v v gs r ds(o n) drain-source on-resistance (w) i d dr ain cu rre nt (a ) t = 150c t = 25c source-drain diode forward voltage v sd source-drain voltage (v) i sd rever se dr ai n curr ent (a) 110 0 10 0 20 0 30 0 40 0 50 0 c rss c os s c iss v gs = 0v f = 1mhz c capacitance (pf) v ds - drain - source voltage (v) 0123456 0 2 4 6 8 10 i d = 2 .5a v ds = 30v gate-source voltage v gate charge capacitance v drain-source voltage q - charge (nc) v gs gate-source voltage (v)
AL8812 document number: ds37099 rev. 1 - 2 6 of 11 www.diodes.com march 2014 ? diodes incorporated a l8812 typical application circuits circuits shown below repr esent connections employed fo r different topologies. to use the in tegrated mosfet the typical configu ration below can be used. AL8812 sw/c ? sw/e gate drive drain source
AL8812 document number: ds37099 rev. 1 - 2 7 of 11 www.diodes.com march 2014 ? diodes incorporated a l8812 typical application circuits (cont.) boost converter test conditions results line regulation v in = 9v to 12v, i o = 200ma 20mv = 0.035% load regulation v in = 12v, i o = 50ma to 200ma 15mv = 0.035% output ripple v in = 12v, i o = 200ma 500mv pp efficiency v in = 12v, i o = 200ma 80%
AL8812 document number: ds37099 rev. 1 - 2 8 of 11 www.diodes.com march 2014 ? diodes incorporated a l8812 typical application circuits (cont.) buck converter test conditions results line regulation v in = 12v to 24v, i o = 500ma 20mv = 0.2% load regulation v in = 24v, i o = 50ma to 500ma 5mv = 0.05% output ripple v in = 24v, i o = 500ma 160mv pp efficiency v in = 24v, i o = 500ma 82%
AL8812 document number: ds37099 rev. 1 - 2 9 of 11 www.diodes.com march 2014 ? diodes incorporated a l8812 design formula table calculation boost buck t on / t off v out + v f -v in ( min ) v out + v f v in ( min ) - v sa t v in ( min ) - v sat - v out ( t on + t off ) 1/f 1/f t off t on + t off t on + t off t on +1 t on +1 t off t off t on ( t on +t off ) - t off ( t on +t off ) - t off c t 4.0 10 - 5 t on 4.0 10 - 5 t on i p k (switch) 2i out ( max ) (t on / t off +1) 2i out ( max ) r sc 0.3 / i p k ( switch ) 0.3 / i p k ( switch ) l (min) ( v in ( min ) ? v sat ) t on (max) ( v in ( min ) ? v sat -v out ) on (max) i p k ( switch ) i p k ( switch ) c o 9 i out t on i p k ( switch ) ( t off + t on ) v ri pp le (pp) 8v ri pp le (pp) v sat = saturation voltage of the output switch. v f = forward voltage drop of the output rectifier. the following power supply characteristics must be chosen: v in - nominal input voltage. v out - desired output voltage, |v out | = 1.25 (1+r2/r1) i out - desired output current. f min - minimum desired output switching frequency at the selected values of v in and i o . v ripple(pp) - desired peak-to-peak output ripple voltage. in practice, t he calculated capacitor value will need to be increased due to its equivalent series resistance and board layout. the ripple voltage should be kept to a low value since it will directly affect the line and load regulation.
AL8812 document number: ds37099 rev. 1 - 2 10 of 11 www.diodes.com march 2014 ? diodes incorporated a l8812 ordering information part number package code packaging tube 13? tape and reel quantity part number suffix quantity part number suffix AL8812fdf-13 fdf u-dfn6040-12 na na 3000/tape & reel -13 marking information (1) u-dfn6040-12 package outline dimensions (all dimensions in mm.) please see ap02002 at http://www.diodes.com/ datasheets/ap02002.pdf for latest version. u-dfn6040-12 dim min max typ a 0.55 0.65 0.60 a1 0 0.05 0.02 a3 - - 0.15 b 0.35 0.45 0.40 d 5.95 6.05 6.00 d1 1.95 2.15 2.05 d2 2.35 2.55 2.45 e - - 1.00 e 3.95 4.05 4.00 e1 2.10 2.30 2.20 e2 1.80 2.00 1.90 l 0.35 0.45 0.40 z - - 0.30 all dimensions in mm a3 a1 seating plane d e e l b z a d1 e1 d2 e2
AL8812 document number: ds37099 rev. 1 - 2 11 of 11 www.diodes.com march 2014 ? diodes incorporated a l8812 suggested pad layout please see ap02001 at http://www.diodes.com/dat asheets/ap02001.pdf for the latest version. 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 rese rve the right to make modifications, enhanc ements, improvements, corrections or ot her changes without further notice to this document and any product descri bed herein. diodes incorporated does not assume any liability ari sing out of the application or use of this document or an y product described herein; neither does di odes incorporated convey any license under its patent or trademark rights, nor the rights of others. any customer or us er of this document or products described herein in such applica tions 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 w hatsoever in respect of any products purchased through unauthoriz ed sales channel. should customers purchase or use diodes inco rporated products for any unintended or una uthorized application, customers shall i ndemnify and hold diodes incorporated and its representativ es harmless against all claims, damages, expenses, and attorney fees arising out of, directly or indirectly, any claim of personal injury or death a ssociated 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. this document is written in english but may be translated into multiple languages for reference. only the english version of t his document is the final and determinative format released by diodes incorporated. life support diodes incorporated products are specifically not authorized for use as critical component s in life support devices or systems without the express written approval of the chief executive offi cer of diodes incorporated. as used herein: a. life support devices or syst ems 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 proper ly 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 devic e 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 ramifi cations of their life support dev ices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-rel ated requirements concerning the ir products and any use of diodes incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or s ystems-related information or support that may be provided by diodes incorporated. further, customers must fully indemnify diodes incorporate d and its representatives against any damages arisi ng out of the use of diodes incorporated pr oducts in such safety-critical, life suppor t devices or systems. copyright ? 2014, diodes incorporated www.diodes.com dimensions value (in mm) c 0.500 g 0.650 g1 0.350 x 0.250 x1 1.075 x2 1.275 x3 2.750 y 0.400 y1 1.150 y2 1.000 y3 2.300 x3 x1 y2 y3 y c x pin1 x2 y1 g1 g

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