AOZ1081-EVB EZBuck™ 1.8A High Efficiency Constant Current Regulator for LEDs — Evaluation Board Note General Description Features The AOZ1081 is a high efficiency, simple to use, 1.8A buck regulator for white LED. The AOZ1081 works from a 4.5V to 16V input voltage range, and provides up to 1.8A of continuous output current with an output voltage adjustable down to 0.25V. ● 4.5V to 16V operating input voltage range ● 100 mΩ internal PFET switch for high efficiency: up to 95% ● Internal Schottky diode ● Internal soft start ● 0.25V internal reference with ±5% accuracy over temperature ● 1.8A continuous output current ● Fixed 1MHz PWM operation ● Cycle-by-cycle current limit ● Short-circuit protection ● Under voltage lockout ● Output over voltage protection ● Thermal shutdown ● Small size SO-8 package The AOZ1081 comes in an SO-8 package and is rated over a -40°C to +85°C ambient temperature range. Applications ● Buck regulators for white LEDs ● Landscape lighting ● Flashlights ● Battery powered backlight applications Evaluation Board Schematic Vin Vin J1 C1 22μF NO POP C2 22μF L1 4.7μH 2 VIN Vin 1 J3 2 6 3 5 GND GND EN COMP R2 61.9kΩ J5 GND AOZ1081AI C4 820pF AGND 3 PGND 1 GND LX LX 8 FB 4 J2 C3 22μF 7 D1 HB White LED D2 HB White LED GND R1 0.25Ω 1/2W Sense Resistor GND Vout D3 HB White LED NO POP J4 R3 0.25Ω 1/2W Sense Resistor R4 0.25Ω 1/2W Sense Resistor GND GND Vb GND Rev. 1.0 November 2008 www.aosmd.com Page 1 of 4 AOZ1081-EVB Component List Ref Designation Part Number Description Manufacturer C1 GRM188R71H104KA01D Ceramic Capacitor, 0603, 100nF/ 50V, X7R, 10% Murata C2,C3 GRM32ER61E226KE15L Ceramic Capacitor, 1210, 22µF/ 25V, X7R, 10% Murata C4 GRM188R71H821KA01D Ceramic Capacitor, 0603, 820pF/ 50V, X7R, 10% Murata Diamond Dragon LW W5AP White LED, SMD, 255 lm at 1400mA OSRAM Coilcraft D1, D2, D3 DO3316P-472 SMD Inductor, 18mΩ, 4.7µH/5.4A R1, R3, R4 RC1206FR-07R250L Film Resistor, 1206, 250mΩ, 1%, 0.25W Yageo R2 RC0603FR-0761k9L Film Resistor, 0603, 61.9k, 1%, 0.1W Yageo U1 AOZ1081AI Buck Convert White LED Driver L1 Rev. 1.0 November 2008 www.aosmd.com AOS Page 2 of 4 AOZ1081-EVB PCB Layout Figure 1. Top Silk Screen Figure 2. Top Layer Figure 3. Bottom Layer Rev. 1.0 November 2008 www.aosmd.com Page 3 of 4 AOZ1081-EVB Quick Start Guide 1. Connect one to three LEDs to the output. Be sure that the total output current should be less than 1.8A. 2. Connect the DC power supply to Vin and GND port. Set DC power supply voltage between 4.5V and 16V. 3. The EN pin is active high. Connect EN pin to Vin if not used. It also can be connect to any voltage source which is higher than 2V and less than Vin. 4. Turn on DC power supply and evaluation circuit will start. 5. Measure input voltage at the Vin and GND port to eliminate the affect of voltage drop on wire between DC power supply and evaluation board. 6. Measure output voltage at the Vout and GND port to eliminate the affect of voltage drop on wire between load and evaluation board. 7. Use oscilloscope to monitor input ripple voltage right across input capacitor C2. 8. Use oscilloscope to monitor output ripple voltage right across output capacitor C3. Note: When testing the ripple voltage, remove the cap of the voltage probe and touch the probe tip directly across the Vin or Vout and GND terminals, as shown in the Figure 4. V GND Figure 4. Voltage Ripple Test This data sheet contains preliminary data; supplementary data may be published at a later date. Alpha &Omega Semiconductor reserves the right to make changes at any time without notice. LIFE SUPPORT POLICY ALPHA & OMEGA SEMICONDUCTOR PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. Rev. 1.0 November 2008 2. A critical component in any component of a life support, device, or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.aosmd.com Page 4 of 4