MAX1951A 19-4689 Rev 0 7/09 1MHz, 2A, 2.6V to 5.5V Input, PWM DC-DC Step-Down Regulator with Enable General Description Features The MAX1951A high-efficiency, DC-DC step-down 2 Compact 0.385in Circuit Footprint switching regulator delivers up to 2A of output current. The device operates from an input voltage range of 2.6V 10F Ceramic Input and Output Capacitors, 2H to 5.5V and provides an adjustable output voltage from Inductor for 2A Output 0.8V to V , making the MAX1951A ideal for on-board IN Efficiency Up to 94% postregulation applications. The MAX1951A total output error is less than 1.5% over load, line, and temperature. 1.5% Output Accuracy Over Load, Line, and Temperature The MAX1951A operates at a fixed frequency of 1MHz with an efficiency of up to 94%. The high operating fre- Guaranteed 2A Output Current quency minimizes the size of external components. Operates from 2.6V to 5.5V Supply Internal soft-start control circuitry reduces inrush current. Short-circuit and thermal-overload protection improve Adjustable Output from 0.8V to V IN design reliability. Internal Digital Soft-Soft The MAX1951A can start up safely with a prebiased or without a preexisting output. This feature simplifies track- Short-Circuit and Thermal-Overload Protection ing supply designs for core and I/O applications and 1MHz Switching Frequency Reduces Component redundant supply designs. Size The MAX1951A is available in an 8-pin SO package Enable Input Audio Shutdown for Reducing and operates over the -40C to +85C extended tem- Power Consumption perature range. Safe Startup into Prebiased Output Applications ASIC/DSP/P/FPGA Core and I/O Voltages Ordering Information Set-Top Boxes PART TEMP RANGE PIN-PACKAGE Networking and Telecommunications MAX1951AESA+ -40C to +85C 8 SO Servers +Denotes a lead(Pb)-free/RoHS-compliant package. TVs Pin Configuration Typical Operating Circuit OUTPUT INPUT 0.8V TO V , UP TO 2A IN 2.6V TO 5.5V TOP VIEW IN LX + V 1 8 IN MAX1951A CC FB V CC EN 2 7 LX MAX1951A GND 3 6 PGND ON COMP EN FB 4 5 COMP OFF PGND GND SO Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. EVALUATION KIT AVAILABLE1MHz, 2A, 2.6V to 5.5V Input, PWM DC-DC Step-Down Regulator with Enable ABSOLUTE MAXIMUM RATINGS IN, V to GND ........................................................-0.3V to +6V Junction-to-Case Thermal Resistance ( ) (Note 2) CC JC COMP, FB, EN to GND...............................-0.3V to (V + 0.3V) CC 8-Pin SO ........................................................................32C/W LX Current (Note 1).............................................................4.5A Operating Temperature Range ...........................-40C to +85C PGND to GND..............................................Internally connected Junction Temperature Range ............................-40C to +150C Continuous Power Dissipation (T = +70C) A Storage Temperature Range .............................-65C to +150C 8-Pin SO (derate 12.2mW/C above +70C).................976mW Lead Temperature (soldering, 10s) .................................+300C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Note 1: LX has internal clamp diodes to PGND and IN. Applications that forward bias these diodes should take care not to exceed the ICs package power dissipation limits. Note 2: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four- layer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial. ELECTRICAL CHARACTERISTICS (V = V = V = 3.3V, V = V = 0V, FB in regulation, T = -40C to +85C, unless otherwise noted. Typical values are at IN CC EN PGND GND A T = +25C.) (Note 3) A PARAMETER CONDITIONS MIN TYP MAX UNITS IN AND V CC IN Voltage Range 2.6 5.5 V Supply Current Switching with no load, LX floating V = 5.5V 7 10 mA IN Shutdown Current EN = GND 0.1 0.4 mA V rising 2.19 2.32 V Undervoltage Lockout CC CC When LX starts/stops switching V Threshold V falling 1.92 2.07 CC COMP COMP Transconductance From FB to COMP, V = 0.8V 40 50 80 S COMP COMP Clamp Voltage, Low V = 2.6V to 5.5V, V = 0.9V 0.6 1 1.45 V IN FB COMP Clamp Voltage, High V = 2.6V to 5.5V, V = 0.7V 1.97 2.13 2.28 V IN FB FB Output Voltage Range When using external feedback resistors to drive FB 0.8 V V IN T = 0C to +85C 0.789 0.796 0.804 FB Regulation Voltage I = 0A to 1.5A, V = 2.6V to A OUT IN V (Error Amplifier Only) 5.5V T = -40C to +85C 0.786 0.804 A FB Input Bias Current PNP input stage -0.1 +0.1 A LX V = 5V 119 IN LX On-Resistance, PMOS I = -180mA V = 3.3V 145 266 m LX IN V = 2.6V 171 IN V = 5V 122 IN LX On-Resistance, NMOS I = 180mA V = 3.3V 133 246 m LX IN V = 2.6V 142 IN 2 MAX1951A