AL8808 COST EFFECTIVE LOW EMI 30V 1A BUCK LED DRIVER Description Pin Assignments The AL8808 is a step-down DC/DC converter designed to drive LEDs (Top View) with a constant current. The device can drive up to 8 LEDs, depending on the forward voltage of the LEDs, in series from a SW 1 5 V voltage source of 6V to 30V. Series connection of the LEDs provides IN identical LED currents resulting in uniform brightness and eliminating GND 2 the need for ballast resistors. The AL8808 switches at frequency up to 1MHz with controlled rise and fall times to reduce EMI. This allows CTRL 3 4 SET the use of small size external components, hence minimizing the PCB area needed. TSOT25 Maximum output current of AL8808 is set via an external resistor connected between the V and SET input pins. Dimming is achieved IN by applying either an analog DC voltage or a PWM signal at the Features CTRL input pin. An input voltage of 0.4V or lower at CTRL switches LED Driving Current Up to 1A off the output MOSFET simplifying PWM dimming. Better Than 5% Accuracy High Efficiency Up to 96% Applications Fast Controlled Falling Edges 7ns Operating Input Voltage from 6V to 30V MR16 Lamps High Switching Frequency Up to 1MHz General Illumination Lamps PWM/DC Input for Dimming Control Built-In Output Open-Circuit Protection Built-In Over-Temperature Protection TSOT25: Available in Green Molding Compound (No Br, Sb) Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2) Halogen and Antimony Free. Green Device (Note 3) Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. 2. See AL8808 Pin Descriiptions Pin Number Pin Name Function 1 SW Switch Pin. CConnect inductorr/freewheeling dioode here, minimiizing track lengthh at this pin to redduce EMI. 2 GND GND Pin Dimming andd On/Off Control Input. Leave ffloating for normaal operation. (VV = 5V, Givees nominal average output currennt I = 0.1/RR ) CTRL OUTnom S Drive too voltage below 00.4V to turn off ouutput current 3 CTRL Drive with an analog volltage (0.5V < V < 2.5V) to addjust output curreent from 20% to 100% of CTTRL I OUTnomm Drive with an analog volltage > 2.6V outpput current will bee 100% of I OUTnoom A PWM signal (low level 0.4V and highh level > 2.6 trannsition times lesss than 1s) allowws the output current to be adjusted bbelow the level seet by the resistorr connected to SET input pin. 4 SET Set Nominal Output Current PPin. Configure thhe output current of the device. Input Supply Pin. Must be loccally decoupled to GND with > 2.22F X7R ceramic capacitor seee applications 5 V IN section for mmore information. Functionaal Block Diaagram Figure 1. AL8808 Blockk Diagram Absolute MMaximum Ratings ( T = +25C, unleess otherwise sppecified.) A Symbol Parameter Ratinggs Unit ESD HBM Human Body MModel ESD Proteection 2.5 kV ESD MM Machine Modeel ESD Protection 2000 V V Continuous V pin voltage relaative to GND -0.3 to +33 V IN IN V SET pin voltagge relative to V pin -5 to +0.3 V SET IN SW voltage reelative to GND -0.3 to +33 V V SW CTRL pin inpuut voltage -0.3 to +6 V V CTRL Switch currentt 1.255 A I SW T Junction Tempperature 1500 C J T Lead Temperaature Soldering 3000 C LEAD T Storage Tempperature Range -55 to ++150 C ST Caution: Stressees greater than thee Absolute Maximmum Ratings specified above, may ccause permanent ddamage to the devvice. These are strt ess ratings only functionnal operation of thee device at these oor any other condittions exceeding thoose indicated in thiis specification is nnot implied. Devicee reliability may be affected by exposure to absolute maximum rating conditions foor extended periodss of time. Semicoonductor devices aare ESD sensitive aand may be damagged by exposure too ESD events. Suittable ESD precautions should be takken when handling and traansporting these deevices. 2 of 20 AL8808 January 2013 Diodes Incorporateed wwww.diodes.com Document numberr: DS35648 Rev. 2 - 2 NEW PRODUCT