AL8807AMP-13 Diodes Incorporated

NOT RECOMMENDED FOR NEW DESIGN USE AL8860 OR AL8861 AL8807A HIGH EFFICIENCY LOW EMI WIDE ANALOG DIMMING RANGE 36V 1A/1.3A BUCK LED DRIVER Description Pin Assignments (Top View) The AL8807A is a step-down DC/DC converter designed to drive LEDs with a constant current. The device can drive up to 9 white high brightness LEDs in series from a voltage source of 6V to 36V. The AL8807A has an extended CTRL pin voltage range increasing its analog dimming range to greater than 10:1. The improved analog dimming range makes it suitable for a variety of lighting applications requiring wide analog dimming ranges. SOT25 The AL8807A switches at frequency up to 1MHz with controlled rise (Top View) and fall times to reduce EMI. This allows the use of small size external components, hence minimizing the PCB area needed. V SET 1 8 IN Maximum output current of AL8807A is set via an external resistor GND N/C 2 7 connected between the V and SET input pins. IN GND SW 3 6 Over Temperature Protection is incorporated so that should a fault CTRL SW 4 5 occur the device will automatically shut-down and only restart when its junction temperature has cooled down, MSOP-8EP Features Applications LED Driving Current up to 1A/1.3A General Illumination Lamps Better than 5% Accuracy 12V Powered LED Lamps High Efficiency Up to 96% Wide Analog Dimming Range LED Lamps Optimally Controlled Switching Speeds Operating Input Voltage from 6V to 36V Wide Analog Input Range for Dimming Control (>10:1) Built-in Protection Features: Open-Circuit LED protection LED Chain Short Circuited Over-Temperature Protection MSOP-8EP and SOT25: Available in Green Molding Compound (No Br, Sb) with lead Free Finish/ RoHS Compliant 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 AL8807A Pin Descriptions Pin Number Pin Name Function SOT25 MSOP-8EP SW 1 5, 6 Switch Pin. Connect inductor/freewheeling diode here, minimizing track length at this pin to reduce EMI. GND 2 2, 3 GND Pin LED current Analog Dimming Control Input. No PWM dimming function. Connected to internal 2.5V V via 50k resistor. So if left open circuit V = V = 2.5V and 100% REF CTRL REF LED current is achieved - giving nominal average output current I = 0.1/R OUTnom S For Analog dimming drive with analog voltage < 2.5V CTRL 3 4 (0.25V < V < 2.5V adjusts output current from 10% to 100% of I . Device will dim the LED current CTRL OUTnom lower than this level but at reduced accuracy. Some devices will not totally turn off the LED current. Soft-start can be implemented by connecting a capacitor to CTRL pin. The amount of soft-start is dependent on ramp-up of input supply voltage and capacitor on CTRL pin. See apps section. SET 4 1 Set Nominal Output Current Pin. Configure the output current of the device. Input Supply Pin. Must be locally decoupled to GND with > 2.2F X7R ceramic capacitor see V 5 8 IN applications section for more information. Exposed pad/TAB. It should be connected to GND and thermal mass for enhanced thermal impedance. EP EP It should not be used as electrical ground conduction path. N/C 7 No connection may be connected to GND. Functional Block Diagram 2 of 20 March 2013 AL8807A Diodes Incorporated www.diodes.com Document number: DS35990 Rev. 3 - 3