MAX1951/MAX1952 19-2622 Rev 2 6/09 1MHz, All-Ceramic, 2.6V to 5.5V Input, 2A PWM Step-Down DC-to-DC Regulators General Description Features The MAX1951/MAX1952 high-efficiency, DC-to-DC 2 Compact 0.385in Circuit Footprint step-down switching regulators deliver up to 2A of out- put current. The devices operate from an input voltage 10F Ceramic Input and Output Capacitors, 2H range of 2.6V to 5.5V and provide an output voltage Inductor for 1.5A Output from 0.8V to V , making the MAX1951/MAX1952 ideal IN Efficiency Up to 94% for on-board postregulation applications. The MAX1951 total output error is less than 1% over load, line, and 1% Output Accuracy Over Load, Line, and temperature. Temperature (MAX1951, Up to 1.5A) The MAX1951/MAX1952 operate at a fixed frequency of Guaranteed 2A Output Current 1MHz with an efficiency of up to 94%. The high operating Operate from 2.6V to 5.5V Supply frequency minimizes the size of external components. Internal soft-start control circuitry reduces inrush current. Adjustable Output from 0.8V to V (MAX1951) IN Short-circuit and thermal-overload protection improve Preset Output of 1.8V (1.5% Accuracy) (MAX1952) design reliability. The MAX1951 provides an adjustable output from 0.8V Internal Digital Soft-Soft to V , whereas the MAX1952 has a preset output of IN Short-Circuit and Thermal-Overload Protection 1.8V. Both devices are available in a space-saving 8-pin SO package. Ordering Information/ Applications Selector Guide ASIC/DSP/P/FPGA Core and I/O Voltages Set-Top Boxes PIN- PART TEMP RANGE OUTPUT PACKAGE Cellular Base Stations MAX1951ESA+ -40C to +85C 8 SO Adj 0.8V to V IN Networking and Telecommunications MAX1952ESA+ -40C to +85C 8 SO Fixed 1.8V +Denotes a lead(Pb)-free/RoHS-compliant package. Pin Configuration Typical Operating Circuit OUTPUT INPUT 0.8V TO V , UP TO 2A IN TOP VIEW 2.6V TO 5.5V IN LX V 1 8 IN MAX1951 CC FB V CC REF 2 7 LX MAX1951 MAX1952 GND 3 6 PGND COMP REF PGND GND FB 4 5 COMP OFF ON SO OPTIONAL 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.1MHz, All-Ceramic, 2.6V to 5.5V Input, 2A PWM Step-Down DC-to-DC Regulators ABSOLUTE MAXIMUM RATINGS IN, V to GND ........................................................-0.3V to +6V Package Junction-to-Case CC COMP, FB, REF to GND.............................-0.3V to (V + 0.3V) Thermal Resistance ( ) (Note 2) ..............................32C/W CC JC LX to Current (Note 1).........................................................4.5A Operating Temperature Range PGND to GND.............................................Internally Connected MAX195 ESA..................................................-40C to +85C Continuous Power Dissipation (T = +85C) Junction Temperature Range ............................-40C to +150C A 8-Pin SO (derate 12.2mW/C above +70C)................976mW Storage Temperature Range .............................-65C to +150C Package Junction-to-Ambient Lead Temperature (soldering, 10s) .................................+300C Thermal Resistance ( ) (Note 2)...............................82C/W JA 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. 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. ELECTRICAL CHARACTERISTICS (V = V = 3.3V, PGND = GND, FB in regulation, C = 0.1F, T = 0C to +85C, unless otherwise noted. Typical values are at REF A IN CC T = +25C.) A PARAMETER CONDITIONS MIN TYP MAX UNITS IN AND V CC IN Voltage Range 2.6 5.5 V Supply Current Sw i tchi ng w i th no loa d, L X unconnected V = 5.5V 6 10 mA IN Shutdown Current COMP = GND 0.5 1.0 mA V rising 2.35 2.5 V Undervoltage Lockout CC CC When LX starts/stops switching V Threshold V falling 2 2.25 CC REF REF Voltage I = 0A, V = 2.6V to 5.5V 1.96 2 2.03 V REF IN REF Load Regulation I = 0 to 40A, V = 2.6V to 5.5V 0.01 0.2 % REF IN REF Line Regulation I = 20A, V = 2.6V to 5.5V 0.01 0.4 % REF IN REF Shutdown Resistance From REF to GND, COMP = GND 12 22 COMP MAX1951 40 60 80 COMP Transconductance From FB to COMP, V = 1.25V S COMP MAX1952 26.7 40 53.3 COMP Clamp Voltage, Low V = 2.6V to 5.5V, V = 1.3V 0.6 1 1.2 V IN FB COMP Clamp Voltage, High V = 2.6V to 5.5V, V = 1.1V 1.97 2.15 2.28 V IN FB COMP Shutdown Resistance From COMP to GND, V = 2V 15 30 IN COMP rising 0.6 1 COMP Shutdown Threshold When LX starts/stops switching V COMP falling 0.17 0.4 COMP Startup Current COMP = GND 15 25 40 A FB Output Voltage Range When using external feedback resistors to drive FB 0.8 V V IN (MAX1951) V = 2.6V to 5.5V MAX1951 0.787 0.795 0.803 FB Regulation Voltage V = 1V to 2V, IN C OMP V (Error Amp Only) I = 0 to 1.5A OUT V = 2.8V to 5.5V MAX1952 1.773 1.8 1.827 IN FB Input Resistance MAX1952 13 18 28 k FB Input Bias Current MAX1951 -0.1 +0.1 A 2 MAX1951/MAX1952