MAX1830/MAX1831 19-2198 Rev 0 10/01 3A, 1MHz, Low-Voltage, Step-Down Regulators with Synchronous Rectification and Internal Switches General Description Features The MAX1830/MAX1831 constant-off-time, pulse-width- 1.5% Output Accuracy modulated (PWM) step-down DC-DC converters are 94% Efficiency ideal for use in 5V and 3.3V to low-voltage conversion necessary in notebook and subnotebook computers. Internal PMOS/NMOS Switches These devices feature internal synchronous rectification 45m /55m On-Resistance at V = +4.5V IN for high efficiency and reduced component count. They 50m /55m On-Resistance at V = +3V IN require no external Schottky diode. The internal 45m Output Voltages PMOS power switch and 55m NMOS synchronous-rec- tifier switch easily deliver continuous load currents up to +3.3V, +2.5V, or +1.5V Pin Selectable (MAX1831) 3A. The MAX1830 produces preset +2.5V, +1.8V, or +2.5V, +1.8V, or +1.5V Pin Selectable (MAX1830) +1.5V output voltage or an adjustable output from +1.1V +1.1V to V Adjustable (Both Devices) IN to V . The MAX1831 produces preset +3.3V, +2.5V, and IN +3V to +5.5V Input Voltage Range +1.5V output voltages and an adjustable output from +1.1V to V They achieve efficiencies as high as 94%. IN. 750A (max) Operating Supply Current The MAX1830/MAX1831 use a unique current-mode, <1A Shutdown Supply Current constant-off-time, PWM control scheme, which includes Programmable Constant-Off-Time Operation Idle Mode to maintain high efficiency during light- load operation. The programmable constant-off-time Up to 1MHz Switching Frequency architecture sets switching frequencies up to 1MHz, Idle Mode Operation at Light Loads allowing the user to optimize performance trade- offs between efficiency, output switching noise, compo- Thermal Shutdown nent size, and cost. Both devices are designed for con- tinuous output currents up to 3A, an internal digital Internal Digital Soft-Start Inrush Current Limiting soft-start to limit surge currents during startup, a 100% 100% Duty Cycle During Low-Dropout Operation duty cycle mode for low-dropout operation, and a low-power shutdown mode that disconnects the input Output Short-Circuit Protection from the output and reduces supply current below 16-Pin QSOP Package 1A.The MAX1830/MAX1831 are available in 16-pin QSOP packages. Ordering Information For similar devices that provide continuous output currents of 1A to 3A, refer to the MAX1644, MAX1623, PART TEMP. RANGE PIN-PACKAGE and MAX1742/MAX1842/MAX1843 data sheets. MAX1830EEE -40C to +85C 16 QSOP MAX1831EEE -40C to +85C 16 QSOP Applications 5V or 3.3V to Low-Voltage Conversion Typical Configuration CPU I/O Supplies Chipset Supplies OUTPUT INPUT Notebook and Subnotebook Computers +1.1V TO IN LX +3V TO V IN +5.5V FB MAX1830 MAX1831 V PGND CC GND SHDN FBSEL COMP REF TOFF Pin Configuration appears at end of data sheet. Idle Mode is a trademark of Maxim Integrated Products, Inc. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. EVALUATION KIT AVAILABLE3A, 1MHz, Low-Voltage, Step-Down Regulators with Synchronous Rectification and Internal Switches ABSOLUTE MAXIMUM RATINGS V , IN, SHDN to GND ............................................-0.3V to +6V Continuous Power Dissipation (T = +70C) CC A 16-Pin QSOP (derate 14mW/C above +70C IN to V .............................................................................0.3V CC 2 GND to PGND.....................................................................0.3V part mounted on 1in of 1oz copper).............................1.12W Operating Temperature Range ...........................-40C to +85C COMP, FB, TOFF, FBSEL, REF to GND .....-0.3V to (V + 0.3V) CC LX Current (Note 1)...............................................................5.1A Storage Temperature Range .............................-65C to +150C Junction Temperature......................................................+150C REF Short Circuit to GND Duration ............................Continuous ESD Protection.....................................................................2kV Lead Temperature (soldering, 10s) ................................ +300C Note 1: LX has internal clamp diodes to PGND and IN. Applications that forward bias the diode should take care not to exceed the ICs package power dissipation. 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, FBSEL = GND, T = 0C to +85C, unless otherwise noted. Typical values are at T = +25C.) IN CC A A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Input Voltage V , V 3.0 5.5 V IN CC FBSEL = V 2.487 2.525 2.563 CC FBSEL = 1.492 1.515 1.538 V = +3V to +5.5V, IN unconnected I = 0 to 3A, LOAD FBSEL = REF V = V FB OUT 1.791 1.818 1.845 (MAX1830) Preset Output Voltage V V OUT FBSEL = GND 1.084 1.100 1.117 V = +3.7V to +5.5V, IN FBSEL = REF I = 0 to 3A, 3.283 3.333 3.383 LOAD (MAX1831) V = V FB OUT V = V = +3V to +5.5V, I = 0, CC IN LOAD Adjustable Output Voltage Range V V V REF IN FBSEL = GND AC Load Regulation Error 2% DC Load Regulation Error 0.4 % Dropout Voltage V V = V = +3V, I = 3A 150 330 mV DO CC IN LOAD Reference Voltage V 1.089 1.100 1.111 V REF Reference Load Regulation V I = -1A to +10A 0.5 2 mV REF REF Current-Limit Threshold I 4.0 4.8 5.4 A LIMIT Maximum Output RMS Current I (Note 4) 3.4 A OUT(RMS) Idle Mode Current Threshold I 0.2 0.6 1.0 A IM V = 4.5V 45 90 IN PMOS Switch On-Resistance R , I = 0.5A ON P LX V = 3V 50 110 IN m V = 4.5V 55 95 IN NMOS Switch On-Resistance R , I = 0.5A ON N LX V = 3V 55 100 IN Switching Frequency f (Note 2) 1 MHz No-Load Supply Current I + I V = 1.2V 325 750 A IN CC FB 2 MAX1830/MAX1831