issue 1 C november 2010 www.diodes.com ? diodes incorporated, 2010 al8400ev1 evaluation board user guide description the al8400ev1, figure 1, is a double sided evaluati on board for the al8400 linear led driver. the evaluation board is preset to drive 150ma through t he led string, the maximum number of which depends on their total forward voltage drop. the operating voltage is between 4 and 18 volts, de pending on the led string to be driven. higher voltages for longer led strings can be used by tapp ing off the board vin from an intermediate point in the led string. note: the evaluation board does not have reverse su pply protection. the sense resistor r2 of 300m sets the leds nominal current at 150ma. figure 1: al8400ev1 evaluation board and connection diagram al8400ev1 connection point definition name description vin positive supply voltage. 4 to 18v gnd supply ground (0v) led a led a connects to the external led string anode led k led k connects to the external led string cathode 4-18vdc leds v
al8400ev1 issue 1 Cnovember 2010 www.diodes.com ? diodes incorporated 2010 2 al8400 device description the al8400 is a 5-terminal adjustable linear led dr iver controller offering excellent temperature stability and output handling capability. the al84 00 simplifies the design of linear and isolated led drivers. with its low 0.2v fb pin, it controls the regulation of led current with minimal power dissipation when compared to traditional linear led drivers. this makes it ideal for medium to high current led driving. al8400 device features low reference voltage (v fb = 0.2v) -40 to 125oc temperature range 3% reference voltage tolerance at 25c low temperature drift 0.2v to 18v open-collector output high power supply rejection (>45db at 300khz) device applications isolated offline led converters linear led driver led signs instrumentation illumination al8400 device packages, pin and definitions sot353 pack al8805 device pin definition name pin no description e1 1 emitter connection. connect to gnd. gnd 2 analog ground: ground return for reference a nd amplifier. connect to e1. v cc 3 supply input. connect a 0.47 f ceramic capacitor close to the device from vcc to gnd. fb 4 feedback input. regulates to 200mv nominal. out 5 output. connect a capacitor close to device between out and gnd. ordering information evalboard order number al8400ev1 please note: evaluation boards are subject to availability and qualified sales leads. device order number AL8400SE-7
al8400ev1 issue 1 Cnovember 2010 www.diodes.com ? diodes incorporated 2010 3 al8400ev1 evaluation board reference design tp1 tp2 tp4 tp5 gnd e1 1 out 5 gnd 2 vcc 3 fb 4 u1 ic - al8400 10k r1 1r3 r2 470nf c1 470nf c2 b c e q1 fzt690b gnd gnd vin led a led k gnd figure 2: al8400ev1 schematic the al8400 provides a simple linear led driver in the form of a constant current circuit. the device will drive the base of the external transist or, q1, appropriately to maintain a voltage of 0.2v at the fb pin. choosing the value of r2 allows the cur rent in the led string (and through q1 and r2) to be selected. the board comes preset to 150ma led current with r 2 at 1.3ohms: i led = 0.2 1.3 = 0.154a the al8400 will tolerate a maximum voltage of 18v at its vcc input, but it can be used over an extended voltage range by taking vin from an int ermediate point in the led string: figure 3: extended voltage range connection diagram vin al8400ev1 board gnd led k +ve dc input 0v input
al8400ev1 issue 1 Cnovember 2010 www.diodes.com ? diodes incorporated 2010 4 bill of materials quantity pcb ident value description suggested source 1 n/a ddb041r1 pcb diodes zetex 1 u1 al8400 diodes zetex 1 q1 fzt690b diodes zetex 2 c1,c2 470nf 0603 ceramic capacitor generic 1 r1 10k 0603 resistor generic 1 r2 1r3 1206 resistor generic circuit accuracy. the accuracy of the circuit is determined by the a ccuracy of the device (+/- 5% over temp) and the accuracy of the current sensing resistor (t yp +/- 1%). for the circuit as set the nominal current is 154m a (0.2/1.3 = 0.15384). the worst cases are 163ma (0.210/1.287 = 0.16317) and 144ma (0.19/ 1.313 = 0.14470). this gives approx 10ma possible variation over the nominal 154ma, about 6. 5%. for further information please contact your diodes inc representative.
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al8400ev1 issue 1 Cnovember 2010 www.diodes.com ? diodes incorporated 2010 8 sales of fices the americas 3050 e. hillcrest drive westlake village, ca 91362-3154 tel: (+1) 805 446 4800 fax: (+1) 805 446 4850 europe kustermannpark balanstra?e 59, d-81541 mnchen germany tel: (+49) 894 549 490 fax: (+49) 894 549 4949 taiwan 7f, no. 50, min chuan road hsin-tien taipei, taiwan tel: (+886) 289 146 000 fax: (+886) 289 146 639 shanghai rm. 606, no.1158 changning road shanghai, china tel: (+86) 215 241 4882 fax (+86) 215 241 4891 shenzhen room a1103-04, anlian plaza, #4018 jintian road futian cbd, shenzhen, china tel: (+86) 755 882 849 88 fax: (+86) 755 882 849 99 korea 6 floor, changhwa b/d, 1005-5 yeongtong-dong, yeongtong-gu, suwon-si, gyeonggi-do, korea 443-813 tel: (+82) 312 731 884 fax: (+82) 312 731 885 important notice diodes incorporated makes no warranty of any kind, express or implied, with regard to this document, including, but not limited to, the implie d warranties of merchantability and fitness for a particular purpose (and their equival ents under the laws of any jurisdiction). diodes incorporated and its subsidiaries reserve th e right to make modifications, enhancements, improv ements, 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 ap plication or use of this document or any product de scribed herein; neither does diodes incorporated convey any license under i ts patent or trademark rights, nor the rights of ot hers. any customer or user of this document or products described here in in such applications shall assume all risks of s uch use and will agree to hold diodes incorporated and all the companies w hose products are represented on diodes incorporate d website, harmless against all damages. diodes incorporated does not warrant or accept any liability whatsoever in respect of any products pur chased through unauthorized sales channels. should customers purch ase or use diodes incorporated products for any uni ntended or unauthorized application, customers shall indemnify and hold diodes incorporated and its representativ es harmless against all claims, damages, expenses, and attorney fees arising out of, directly or indirectly, any c laim of personal injury or death associated with such unintended or unauthoriz ed application. products described herein may be covered by one or more united states, international or foreign patent s pending. product names and markings noted herein may also be covered by one or more united states, international or for eign trademarks. life support diodes incorporated products are specifically not a uthorized for use as critical components in life su pport devices or systems 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 per form when properly used in accordance with instruct ions for use provided in the labeling can be reasonably expecte d to result in significant injury to the user. b. a critical component is any component in a lif e support device or system whose failure to perform can be reasonably be expected to cause the failure of the life suppor t device or to affect its safety or effectiveness. customers represent that they have all necessary ex pertise 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, regulato ry and safety-related requirements concerning their products and any use of diodes incorporated products in such safety-crit ical, 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 indemnify diodes incorporated and its representati ves against any damages arising out of the use of diodes incorporat ed products in such safety-critical, life support d evices or systems. copyright ? 2009, diodes incorporated www.diodes.com
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