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AL5802 30v, adjustable current sink linear led driver AL5802 document number: ds35516 rev.4 - 2 1 of 11 www.diodes.com november 2011 ? diodes incorporated advance information new product description the AL5802 combines a high gain npn transistor with a pre- biased npn transistor to make a simple small footprint led driver. the led current is set by an external resistor connected to from rext pin (6) to gnd pin (4), the internal high gain transistor develops approximately 0.6v across the external resistor. the AL5802 open-collector output can operate from 0.8v to 30v enabling it to operate from 5v to 24v power supplies without additional components. pwm dimming of the led current can be achieved by either driving the bias pin (2) with a low impedance voltage source, or driving the en pin (3) with an external open- collector npn transistor or open-drain n-channel mosfet. the AL5802 is available in a sot26 package and is ideal for driving 20ma to 120ma led currents. pin assignments (top view) sot26 features ? reference voltage v rset = 0.65v ? -40 to 125oc temperature range ? 0.8v to 30v open-collector output ? negative temperature co-efficient ? automatically reduce the led current at high temperatures ? low thermal impedance sot26 with copper leadframe ? sot26: available in ?green? molding compound (no br, sb) ? qualified to aec-q101 standards for high reliability applications ? linear led driver ? led signs ? offline led luminaries typical application circuit 654 123 q2 q1
AL5802 30v, adjustable current sink linear led driver AL5802 document number: ds35516 rev.4 - 2 2 of 11 www.diodes.com november 2011 ? diodes incorporated advance information new product pin descriptions pin number name function 1 out open-collector led driver output 2 bias biases the open collector output transistor 3 en enable pin for pwm dimming. provides access to the base of q2 and collector of q1 4 gnd ground reference point for setting led current 5 fb feedback pin. should be connected to pin 6. 6 rext current sense pin. led current s ensing resistor should be connected from here to gnd. functional block diagram fig. 1 block diagram absolute maximum ratings symbol characteristics values unit v out output voltage relative to gnd 30 v v bias bias voltage relative to gnd (note 1) 30 v v fb led voltage relative to gnd 6 v v en en voltage relative to gnd 6 v v re x t rext voltage relative to gnd 6 v i out output current 150 ma t j operating junction temperature -40 to 150 c t st storage temperature -55 to 150 c these are stress ratings only. operation outside the abs olute maximum ratings may cause device failure. operation at the absolute maximum rating for ex tended periods may reduce device reliability. notes: 1.with pins 5 and 6 connected together.
AL5802 30v, adjustable current sink linear led driver AL5802 document number: ds35516 rev.4 - 2 3 of 11 www.diodes.com november 2011 ? diodes incorporated advance information new product package thermal data characteristic symbol value unit power dissipation ( note 2 ) @ t a = 25c power dissipation ( note 3 ) @ t a = 25c power dissipation ( note 4 ) @ t a = 25c p d 0.37 0.87 1 w thermal resistance, junction to ambient air (note 2) @ t a = 25c thermal resistance, junction to ambient air (note 3) @ t a = 25c thermal resistance, junction to ambient air (note 4) @ t a = 25c r ja 335 143 120 c/w notes: 2.device mounted on fr-4 pcb, 2oz with minimum recommended pad layout. 3.device mounted on 25mm x 25mm 2oz copper board. 4.device mounted on 50mm x 50mm 2oz copper board. recommended operating conditions symbol parameter min max unit v bias supply voltage range 4.5 30 v v out out voltage range 0.8 30 i led led pin current ( note 5 ) 10 120 ma t a operating ambient temper ature range -40 125 c notes: 5.subject to ambient temperature, power dissipation and pcb. electrical characteristics npn transistor ? q1 @t a = 25c unless otherwise specified symbol characteristic test condition min typ max unit v ( br ) ceo collector-emitter breakdown voltage (note 6) i c = 1.0ma, i b = 0 40 v v ( br ) ebo emitter-base breakdown voltage i e = 10a, i c = 0 6.0 v i ce x collector cutoff current v ce = 30v, v eb ( off ) = 3.0v 50 na i bl base cutoff current v ce = 30v, v eb ( off ) = 3.0v 50 na h fe dc current gain i c = 100a, v ce = 1.0v i c = 1.0ma, v ce = 1.0v i c = 10ma, v ce = 1.0v 40 70 100 ? ? 300 v ce ( sat ) collector-emitter sa turation voltage i c = 10ma, i b = 1.0ma 0.20 v v be ( sat ) base-emitter satu ration voltage i c = 10ma, i b = 1.0ma 0.65 0.85 v npn pre-biased transistor ? q2 @t a = 25c unless otherwise specified symbol characteristic test condition min typ max unit v (br)cbo collector-base breakdown voltage i c = 50 a, i e = 0 30 v v ( br ) ceo collector-emitter breakdown voltage (note 6) i c = 1ma, i b = 0 30 v v ( br ) ebo emitter-base breakdown voltage i e = 50a, i c = 0 5.0 v i cbo collector cut-off current v cb = 30v, i e = 0 0.5 a i ebo emitter cut-off current v eb = 4v, i c = 0 0.5 a v ce ( sat ) collector-emitter saturation voltage (note 6) i c = 10ma, i b = 1ma 0.3 v h fe dc current gain (note 6) v ce = 5v, i c = 150ma 100 r 1 input resistance 7 10 13 k *characteristics of transistor only. notes: 6. measured under pulsed condition. pulse width = 300s. duty cycle 2%.
AL5802 30v, adjustable current sink linear led driver AL5802 document number: ds35516 rev.4 - 2 4 of 11 www.diodes.com november 2011 ? diodes incorporated advance information new product thermal characteristics fig. 2derating curve ambient temperaure (c) fig. 3max power vs. area fig. 4thermal resistance vs. area
AL5802 30v, adjustable current sink linear led driver AL5802 document number: ds35516 rev.4 - 2 5 of 11 www.diodes.com november 2011 ? diodes incorporated advance information new product typical performance characteristics notes 7.v out in the ?output current vs v out ? graphs limited by power dissipation in the device fig. 5 output current vs. v out fig. 6 output current vs. r ext fig. 7 output current vs. v out fig. 8 output current vs. v out fig. 9 output current vs. v out fig. 10 output current vs. v bias
AL5802 30v, adjustable current sink linear led driver AL5802 document number: ds35516 rev.4 - 2 6 of 11 www.diodes.com november 2011 ? diodes incorporated advance information new product fig. 13 output current vs. v bias fig. 12 output current vs. v bias fig. 11 output current vs. v bias
AL5802 30v, adjustable current sink linear led driver AL5802 document number: ds35516 rev.4 - 2 7 of 11 www.diodes.com november 2011 ? diodes incorporated advance information new product application information fig. 14typical applic ation circuit for linear mode current sink led driver fig. 15application circuit for increasing led current the AL5802 has been designed for driving low current leds with typical led current of 20ma to 100ma. it provides a cost effective way for driving low current leds compared with more complex switching regulator solutions. furthermore, it reduces the pcb board area of the solution as there is no need for external components like inductors, capacitors and switching diodes. figure 14 shows a typical application circuit diagram for driving an led or string of leds. the npn transisto r q1 measures the led current by sensing the voltage across an external resistor r ext . q1 uses its v be as reference to set the voltage across r ext and controls the base current into q2. q2 operates in linear mode to regulate the led current. the led current is i led = v be(q1) / r ext from this, for any required led current the necessary external resistor r ext can be calculated from r ext = v be(q1) / i led two or more AL5802 can be connected in parallel to construct higher current led strings as shown in figure 15. consideration of the expected linear mode power dissipation must be factored into the design, with respect to the AL5802's thermal resistance. the maximum voltage ac ross the device can be calculated by taking the maximum supply voltage less the voltage across the led string. v ce(q2) = v cc ? v led ? v be(q1) p d = v ce(q2) * i led + ( v cc ? v be(q2) ? v be(q1) ) 2 / r 1 as the output current of AL5802 increases, it is necessary to provide appropriate thermal relief to the device. the power dissipation supported by the device is dependent upon the pcb board material, the copper area and the ambient temperature. the maximum dissipation the device can handle is given by: p d = ( t j(max) - t a ) / r ja refer to the thermal characteristic graphs on page 4 for selecting the appropriate pcb copper area.
AL5802 30v, adjustable current sink linear led driver AL5802 document number: ds35516 rev.4 - 2 8 of 11 www.diodes.com november 2011 ? diodes incorporated advance information new product pwm dimming can be achieved by driv ing the en pin. an external open-collector np n transistor or open-drain n-channel mosfet can be used to drive the en pin as shown in figur e 16. dimming is achieved by turning the le ds on and off for a portion of a single cy cle. the pwm signal can be provided by a mi cro-controller or analog circuitry. figure 17 is a typical response of led current vs pwm dut y cycle on the en pin. -or- fig. 16application circui ts for led driver with pwm dimming functionality fig. 17 typical led current response vs.pwm duty cycle for r ext = 13 ? at 400hz pwm frequency 0 10 20 40 60 80 100 led current (ma) pwm duty cycle (%) 20 0 30 40 50 60
AL5802 30v, adjustable current sink linear led driver AL5802 document number: ds35516 rev.4 - 2 9 of 11 www.diodes.com november 2011 ? diodes incorporated advance information new product to remove the potential of incorrect connection of the power supply damaging the lamp?s leds, many systems use some form of reverse polarity protection. one solution for reverse input polarit y protection is to simply use a diode with a low v f in-line with the driver/led combination. the low v f increases the available voltage to the led stack and dissipates less power. a circuit example is presented in fig. 18 using diodes inc. sbr? (super barrier rectifier) technology. an sdm10u45lp (0.1a/45v) is shown, providing exceptionally low v f for its package size of 1mm x 0.6mm, equivalent to an 0402 chip style package. other reverse voltage ratings are al so available in diodes? website such as the sbr02u100lp (0.2a/100v) or sbr0220lp (0.2a/20v). automotive applications commonly use this method for reverse battery protection. a second approach, shown in fig. 19, improves upon the method shown in fig. 18. whereas the met hod in fig. 18 protects the light engine, it will not function until the problem has been diagnosed and corrected. the method shown in fig. 19 not only provides reverse polarity protection, it also corrects the reversed polarity, allowing the light engine to function. the bas40brw incorporates four low v f , schottky diodes into a single package and allows more voltage available for the led stack and dissipates less power that standard rectifier bridges. fig. 18 application circ uit for led driver with reverse polarity protection fig. 19 application circui t for led driver with assured operation regardless of polarity r s a l5802 v s bas40brw r s a l5802 sdm10u45lp v s sbr is a registered trademark of diodes incorporated.
AL5802 30v, adjustable current sink linear led driver AL5802 document number: ds35516 rev.4 - 2 10 of 11 www.diodes.com november 2011 ? diodes incorporated advance information new product ordering information device packaging (notes 8&9) 7? tape and reel quantity part number suffix AL5802 sot26 3,000/tape & reel -7 notes: 8.eu directive 2002/95/ec (rohs). all applicable rohs ex emptions applied, see eu directive 2002/95/ec annex notes . 9.pad layout as shown on diodes inc. suggested pad layout docum ent ap02001, which can be found on our website athttp://www.dio des.com. marking information l102 = product type marking code ym = date code marking y = year (ex: y = 2011) m = month (ex: 9 = september) date code key year 2011 2012 2013 2014 2015 2016 2017 code y z a b c d e month jan feb mar apr may jun jul aug sep oct nov dec code 1 2 3 4 5 6 7 8 9 o n d package outline dimensions l102 ym sot26 dim min max typ a 0.35 0.50 0.38 b 1.50 1.70 1.60 c 2.70 3.00 2.80 d ? ? 0.95 h 2.90 3.10 3.00 j 0.013 0.10 0.05 k 1.00 1.30 1.10 l 0.35 0.55 0.40 m 0.10 0.20 0.15 0 8 ? all dimensions in mm a m j l d b c h k
AL5802 30v, adjustable current sink linear led driver AL5802 document number: ds35516 rev.4 - 2 11 of 11 www.diodes.com november 2011 ? diodes incorporated advance information new product suggested pad layout 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 described herein. diodes incorporated does not assume any liability ari sing out of the application or use of this document or any product described herein; neither does diodes 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 in corporated and all the companies w hose products are represented on diodes incorporated website, harmless against all damages. diodes incorporated does not warrant or accept any liability what soever in respect of any pr oducts purchased through unauthoriz ed sales channel. should customers purchase or use diodes in corporated products for any unintended or unauthorized application, customers shall i ndemnify and hold diodes incorporated and its representatives harmless agai nst all claims, damages, expenses, and attorney fees 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 mo re 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 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 prop erly 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 ramifications of their life support dev ices or systems, and acknowledge and agree that they are solely responsible fo r all legal, regulatory and safety -related requirements concerning their products and any use of diodes incorporated products in such safety-cri tical, life support devices or systems, notwithstanding any devic es- or systems- related information or support that may be provided by diodes inco rporated. further, customers must fully indemnify diodes inc orporated and its representatives against any damages aris ing out of the use of diodes incorporated products in such safety-critical, life su pport devices or systems. copyright ? 2011, diodes incorporated www.diodes.com dimensions value (in mm) z 3.20 g 1.60 x 0.55 y 0.80 c1 2.40 c2 0.95 x z y c1 c2 c2 g

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