AOZ1012D

^lwNMNOa= EZBuck™ 3A Simple Buck Regulator April 2006 General Description The AOZ1012D is a high efficiency, simple to use, 3A buck regulator. The AOZ1012D works from a 4.5V to 16V input voltage range, and provides up to 3A of continuous output current with an output voltage adjustable down to 0.8V. The AOZ1012D comes in 4X5 DFN-8 packages and is rated over a -40°C to +85°C ambient temperature range. Features • 4.5V to 16V operating input voltage range • 50 m Ω internal PFET switch for high efficiency: up to 95% • Internal Schottky Diode • Internal soft start • Output voltage adjustable to 0.8V • 3A continuous output current • Fixed 500kHz PWM operation • Cycle-by-cycle current limit • Short-circuit protection • Thermal shutdown • Small size DFN-8 packages Applications • Point of load dc/dc conversion • PCIe graphics cards • Set top boxes • DVD drives and HDD • LCD panels • Cable modems • Telecom/Networking/Datacom equipment Typical Application VIN C1 22uF VIN From uPC EN L1 3.3uH AOZ1012D COMP RC LX R1 VOUT +3.3V Output @3A C2 FB GND R2 47uF CC Figure 1. 3.3V/3A Buck Down Regulator April 2006 www.aosmd.com Page 1 of 17 ^lwNMNOa Ordering Information Part Number AOZ1012DI Ambient Temperature Range -40°C to +85°C Package DFN-8 Environmental RoHS Compliant Pin Configuration 4X5 DFN VIN PGND AGND FB Pin Description Pin Number 1 2 3 Pin Name VIN PGND AGND Pin Function Supply voltage input. When VIN rises above the UVLO threshold the device starts up. Power ground. Electrically needs to be connected to AGND. Reference connection for controller section. Also used as thermal connection for controller section. Electrically needs to be connected to PGND. The FB pin is used to determine the output voltage via a resistor divider between the output and GND. External loop compensation pin. The enable pin is active high. Connect EN pin to VIN if not used. Do not leave the EN pin floating. PWM output connection to inductor. Thermal connection for output stage. 1 8 LX 2 3 AGND 4 5 7 6 LX LX EN COMP 4 5 6 7,8 FB COMP EN LX Absolute Maximum Ratings(1) Parameter Supply Voltage (VIN) LX to AGND EN to AGND FB to AGND COMP to AGND PGND to AGND Junction Temperature (TJ) Storage Temperature (TS) Units 18V -0.7V to VIN+0.3V -0.3V to VIN+0.3V -0.3V to 6V -0.3V to 6V -0.3V to +0.3V +150°C -65°C to +150°C Recommend Operating Ratings(2) Parameter Supply Voltage (VIN) Output Voltage Range Ambient Temperature (TA) Package Thermal Resistance DFN-8 (ΘJA) Units 4.5V to 16V 0.8V to VIN -40°C to +85°C 53° C/W April 2006 www.aosmd.com Page 2 of 17 ^lwNMNOa Electrical Characteristics TA = 25°C, VIN = VEN = 12V, VOUT = 3.3V unless otherwise specified(4). Parameter Supply Voltage Input Under-Voltage Lockout Threshold Supply Current (Quiescent) Shutdown Supply Current Feedback Voltage Load Regulation Line Regulation Feedback Voltage Input Current EN Input Threshold EN Input Hysteresis Modulator Frequency Maximum Duty Cycle Minimum Duty Cycle Error Amplifier Voltage Gain Error Amplifier Transconductance Protection Current Limit Over-Temperature Shutdown Limit Soft Start Interval Output Stage High-Side Switch On-Resistance Symbol VIN VUVLO IIN IOFF VFB Conditions VIN rising VIN falling IOUT = 0, VFB = 1.2V, VEN >2V VEN = 0V 0.782 MIN 4.5 4.0 3.7 2 3 0.8 0.5 1 TYP MAX 16 UNITS V V V mA µA 3 20 0.818 IFB VEN VHYS fO DMAX DMIN Off threshold On threshold 200 0.6 2.0 100 350 100 500 600 6 500 200 V % % nA V V mV kHz % % V/V µA/V A °C °C ms mΩ mΩ ILIM TJ rising TJ falling tSS VIN = 12V VIN = 5V 4 145 100 4 40 65 5 50 85 Notes: 1. Exceeding the Absolute Maximum ratings may damage the device. 2. The device is not guaranteed to operate beyond the Maximum Operating ratings. 3. Devices are inherently ESD sensitive, handling precautions are required. Human body model rating: 1.5KΩ in series with 100pF. 4. Specification in BOLD indicate an ambient temperature range of -40°C to +85°C. These specifications are guaranteed by design. April 2006 www.aosmd.com Page 3 of 17 ^lwNMNOa Functional Block Diagram Vin EN UVLO & POR 5V LDO REGULATOR Internal +5V OTP REFERENCE & BIAS + ISEN SOFTSTART ILIMIT Q1 0.8V FB + + EAMP PWM – COMP + PWM CONTROL LOGIC LEVEL SHIFTER + FET DRIVER LX LX D1 COMP 500Khz OSCILLATOR AGND PGND April 2006 www.aosmd.com Page 4 of 17 ^lwNMNOa Typical Performance Characteristics Circuit of figure 1. TA = 25°C, VIN = VEN = 12V, VOUT = 3.3V unless otherwise specified. Light load (DCM) operation Vin ripple 0.1V/div Full load (CCM) operation Vin ripple 0.1V/div Vo ripple 20mV/div Vo ripple 20mV/div Iin 2A/div Iin 2A/div VLX 10V/div VLX 10V/div 1us/div Start up to full load Vin 5V/div 1us/div Full load to turn off Vo 1V/div Vin 5V/div Iin 2A/div Vo 1V/div Iin 2A/div 1ms/div 50% to 100% Load transient 1ms/div Light load to turn off Vo Ripple 0.1V/div Vin 5V/div Io 2A/div Vo 1V/div Iin 2A/div 100us/div 1s/div April 2006 www.aosmd.com Page 5 of 17 ^lwNMNOa Short circuit protection Short circuit recovery Vo 2V/div Vo 2V/div IL 2A/div IL 2A/div 100us/div 1ms/div Efficiency (Vin=12V) vs. load current AOZ1012D Efficiency 8.0V output 95% 5.0V output 90% Eff (%) 3.3V output 85% 8 V out 5 V out 3.3 V out 80% 75% 0 0.5 1 1.5 2 2.5 3 Load current (A) April 2006 www.aosmd.com Page 6 of 17 ^lwNMNOa Thermal de-rating curves for DFN-8 package part under typical input and output condition Circuit of figure 1. 25ºC ambient temperature and natural convection (air speed