MAX1649/MAX1651 19-0305 Rev 3 3/09 5V/3.3V or Adjustable, High-Efficiency, Low-Dropout, Step-Down DC-DC Controllers General Description Features The MAX1649/MAX1651 BiCMOS, step-down, DC-DC More than 90% Efficiency (10mA to 1.5A Loads) switching controllers provide high efficiency over loads More than 12.5W Output Power ranging from 1mA to more than 2.5A. A unique, current- Less than 0.3V Dropout Voltage at 500mA limited pulse-frequency-modulated (PFM) control scheme gives these devices the benefits of pulse-width-modula- 100A Max Quiescent Supply Current tion (PWM) converters (high efficiency at heavy loads), 5A Max Shutdown Supply Current while using only 100A of supply current (vs. 2mA to 16V Max Input Voltage 10mA for PWM converters). Dropout performance down to 300mV is provided by a high switch duty cycle (96.5%) 5V (MAX1649), 3.3V (MAX1651), or Adjustable and a low current-sense threshold (110mV). Output Voltage A high switching frequency (up to 300kHz) allows these Current-Limited Control Scheme devices to use miniature external components. Up to 300kHz Switching Frequency The MAX1649/MAX1651 have dropout voltages less Up to 96.5% Duty Cycle than 0.3V at 500mA and accept input voltages up to 16V. Output voltages are preset at 5V (MAX1649), or 3.3V (MAX1651). They can also be adjusted to any Ordering Information voltage from 1.5V to the input voltage by using two resistors. PART TEMP RANGE PIN-PACKAGE MAX1649CPA 0C to +70C 8 Plastic DIP These step-down controllers drive external P-channel MOSFETs at loads greater than 12.5W. If less power is MAX1649CSA 0C to +70C 8 SO required, use the MAX639/MAX640/MAX653 step-down MAX1649C/D 0C to +70C Dice* converters with on-chip FETs, which allow up to a MAX1649EPA -40C to +85C 8 Plastic DIP 225mA load current. MAX1649ESA -40C to +85C 8 SO Applications MAX1651CPA 0C to +70C 8 Plastic DIP MAX1651CSA 0C to +70C 8 SO PDAs MAX1651C/D 0C to +70C Dice* High-Efficiency Step-Down Regulation MAX1651EPA -40C to +85C 8 Plastic DIP 5V-to-3.3V Green PC Applications MAX1651ESA -40C to +85C 8 SO Battery-Powered Applications *Dice are tested at T = +25C. A Typical Operating Circuit Pin Configuration INPUT 3.6V TO 16V TOP VIEW V+ OUT 1 8 GND MAX1651 FB 2 7 EXT ON/OFF SHDN CS MAX1649 SHDN 3 CS 6 MAX1651 EXT P OUTPUT REF 4 5 V+ 3.3V OUT REF DIP/SO FB GND Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim s website at www.maxim-ic.com. EVALUATION KIT AVAILABLE5V/3.3V or Adjustable, High-Efficiency, Low-Dropout, Step-Down DC-DC Controllers ABSOLUTE MAXIMUM RATINGS Supply Voltage, V+ to GND.......................................-0.3V, +17V Operating Temperature Ranges REF, SHDN, FB, CS, EXT, OUT .......................-0.3V, (V+ + 0.3V) MAX1649C A, MAX1651C A ..............................0C to +70C Continuous Power Dissipation (T = +70C) MAX1649E A, MAX1651E A............................-40C to +85C A Plastic DIP (derate 9.09mW/C above +70C) .............727mW Storage Temperature Range .............................-65C to +160C SO (derate 5.88mW/C above +70C)..........................471mW Lead Temperature (soldering, 10sec) .............................+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. ELECTRICAL CHARACTERISTICS (V+ = 5V, T = T to T , unless otherwise noted. Typical values are at T = +25C.) A MIN MAX A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS V+ Input Voltage Range V+ V < V+ 3.0 16 V OUT V+ = 16V, SHDN 0.4V (operating, switch off) 78 100 Supply Current I+ V+ = 16V, SHDN 1.6V (shutdown) 2 A V+ = 10V, SHDN 1.6V (shutdown) 15 MAX1649C, MAX1651C 1.470 1.5 1.530 FB Trip Point V MAX1649E, MAX1651E 1.4625 1.5 1.5375 MAX1649C, MAX1651C 50 FB Input Current I nA FB MAX1649E, MAX1651E 70 MAX1649, V+ = 5.5V to 16V 4.80 5.0 5.20 Output Voltage V V OUT MAX1651, V+ = 3.6V to 16V 3.17 3.3 3.43 MAX1649C, MAX1651C, I = 0A 1.470 1.5 1.530 REF Reference Voltage V V REF MAX1649E, MAX1651E, I = 0A 1.4625 1.5 1.5375 REF REF Load Regulation 0A I 100A, sourcing only 410 mV REF REF Line Regulation 3V V+ 16V 40 100 V/V MAX1649, 5.5V V+ 16V, 2.6 I = 1A LOAD Output Voltage Circuit of mV/V Line Regulation Figure 1 MAX1651, 3.6V V+ 16V, 1.7 I = 1A LOAD MAX1649, 0A I 1.5A, LOAD -47 V = 10V IN Output Voltage Circuit of mV/A Load Regulation Figure 1 MAX1651, 0A I 1.5A, LOAD -45 V = 5V IN MAX1649, V+ = 10V, 90 I = 1A LOAD Circuit of Efficiency % Figure 1 MAX1651, V+ = 5V, 90 I = 1A LOAD SHDN Input Current V+ = 16V, SHDN = 0V or V+ 1 A SHDN Input Voltage High V 3V V+ 16V 1.6 V IH SHDN Input Voltage Low V 3V V+ 16V 0.4 V IL 2 MAX1649/MAX1651