AOZ1024DI-EVB EZBuck™ 4A Synchronous Buck Regulator Evaluation Board Note General Description Features The AOZ1024DI evaluation board is a fully assembled and tested circuit board built with the AOZ1024DI buck regulator IC. It outputs an adjustable voltage up to 4A of continuous current. The evaluation board requires an input voltage from 4.5 to 16V. The output voltage is preset at 3.3V and can be adjusted down to 0.8V. ● ● 4.5V to 16V operating input voltage range Output voltage preset to 3.3V, adjustable to as low as 0.8V 4A continuous output current Fixed 500kHz PWM operation Internal soft start Cycle-by-cycle current limit Short-circuit protection Thermal shutdown ● Enables single layer board design ● ● ● ● The AOZ1024DI-EVB circuit has features like current limit, short circuit protection, input under voltage lock out, internal soft start and thermal shut down. It operates at a fixed 500kHz switching frequency. The integrated internal MOSFETs minimize component count, board area and total cost. ● ● Applications The AOZ1024DI-EVB demonstrates the simple buck converter design. Only one resistor value change is needed for different output voltage designs. The AOZ1024DI-EVB also supports single layer board design. ● ● ● ● ● ● ● Point of load DC/DC conversion PCIe graphics cards Set top boxes DVD drives and HDD LCD panels Cable modems Telecom/Networking/Datacom equipment Evaluation Board Schematic Cp open Cc Rc GND U1 EN R4 0 Vin 6 EN AGND COM P 3 GND R3 Vin LX 8 Vi n C1 226 LX 7 1 GND 31.6k 1 L 2 GND 4R7 C2 226 C3 226 GND GND Rev. 1.0 July 2009 R1 FB 4 EN C5 2 C4 open R2 10k 5 PGND GND GND GND www.aosmd.com Page 1 of 4 AOZ1024DI-EVB Table 1. Component List Ref Designation Part Number Description Manufacturer C1, C2, C3 GRM32ER61E226KE15L Cap, 22µF/25V, 1210, X6R, 10% muRata C4, Cp Open Cap, 0603 TDK, muRata C5 GRM188R71H104KA01D Cap, 0.1µF/50V, 0603, X7R, 10% muRata C1608C0G1H102J Cap, 1nF/50V, 0603, X7R 10% Cen GRM188R71H102KA01D TDK muRata Cc GRM188R71H222KA01D Cap, 2.2nF/50V, 0603, X7R 10% muRata L VLF10045-4R7N6R1 Inductor, 4.7µH, 6.1A TDK R1 31.6k Res, 31.6k, 0603, 1% R2, Rc 10k Res, 10k, 0603, 1% R3 Open R4 0 Res,0, 0603 U1 AOZ1024DI IC, MAX 4A, DFN5x4 AOS Output voltage is set by R1: R1= R2 • (Vout – 0.8) / 0.8. Table 2 below shows the value of R1 at typical output voltages. Table 2. R1 (kΩ) R2 (kΩ) 0.8 1 Open 1 2.49 10 1.2 5.11 10 1.5 8.66 10 1.8 12.7 10 2.5 21.5 10 3.3 31.6 10 5 52.3 10 Vout (V) Rev. 1.0 July 2009 www.aosmd.com Page 2 of 4 AOZ1024DI-EVB PCB Layout Figure 1. Top Silk Screen Figure 2. Top Layer Figure 3. Bottom Layer Rev. 1.0 July 2009 www.aosmd.com Page 3 of 4 AOZ1024DI-EVB Quick Start Guide 1. Connect the terminals of load to Vout and GND port. 2. Connect the DC power supply to Vin and GND port. Set DC power supply voltage to between 4.5V and 16V. 3. EN pin is connected to Vin via a 0Ohm resistor in the demo board. If a separate enable signal is desired, connect EN pin to any voltage source between 2.0V and 16V. 4. Measure input voltage at the Vin and GND ports to eliminate the effect of voltage drop on the wire between DC power supply and evaluation board. 5. Measure output voltage at the Vout and GND ports to eliminate the effect of voltage drop on the wire between load and evaluation board. 6. Use an oscilloscope to monitor the input ripple voltage across input capacitor C1. 7. Use an oscilloscope to monitor the output ripple voltage 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 Figure 4. V GND Figure 4. Voltage Ripple Test 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 July 2009 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