MAX1744/MAX1745 19-1776 Rev 4 8/09 High-Voltage, Step-Down DC-DC Controllers in MAX General Description Features The MAX1744/MAX1745 are step-down DC-DC con- High-Voltage Operation (Up to 36V IN) trollers capable of handling up to 36V inputs. These Efficiency > 90% parts use a proprietary current-limited control scheme for excellent light- and full-load efficiency, while their Output Power Capability Exceeds 50W 330kHz (max) switching frequency permits small exter- 10-Pin Max Package nal components for space-critical applications. Operation to 100% duty cycle permits the lowest possi- Low-Dropout Voltage ble dropout voltage. 100% (max) Duty Cycle The MAX1744 contains an internal feedback network that provides a pin-selectable output voltage of either 90A Quiescent Current 3.3V or 5V. The MAX1745 uses an external feedback network to generate an adjustable output voltage 4A Shutdown Current between 1.25V and 18V. Up to 330kHz Switching Frequency The MAX1744/MAX1745 are available in a space-sav- Output Voltage ing 10-pin MAX package. 5V or 3.3V (MAX1744) Adjustable 1.25V to 18V (MAX1745) Applications Current-Limited Control Scheme Automotive Electronics Telecom Systems Ordering Information Wall-Cube-Powered Devices PART TEMP RANGE PIN-PACKAGE Industrial Control Systems MAX1744EUB+ -40C to +85C 10 MAX Firewire /IEEE 1394 MAX1744AUB+ -40C to +125C 10 MAX MAX1744EUB/V+ -40C to +85C 10 MAX MAX1745EUB+ -40C to +85C 10 MAX MAX is a registered trademark of Maxim Integrated Products, Inc. MAX1745AUB+ -40C to +125C 10 MAX Firewire is a registered trademark of Apple, Inc. MAX1745EUB/V+ -40C to +85C 10 MAX IEEE is a registered service mark of the Institute of Electrical +Denotes a lead(Pb)-free/RoHS-compliant package. and Electronics Engineers, Inc. /V Denotes an automotive qualified part. Typical Operating Circuit Pin Configuration IN TOP VIEW 4.5V TO 36V + IN VH EXT P GND 1 10 IN ON SHDN OFF VL 2 9 EXT 5V MAX1744 3.3V 3/5 REF 3 8 VH MAX1745 MAX1744 3/5 (FB) 4 7 SHDN VL CS OUT 5 6 CS REF OUT OUT 3.3V GND MAX OR 5V ( ) ARE FOR MAX1745 ONLY. 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 AVAILABLEHigh-Voltage, Step-Down DC-DC Controllers in MAX ABSOLUTE MAXIMUM RATINGS IN, EXT, SHDN to GND...........................................-0.3V to +38V Operating Temperature Range MAX174 EUB ..................................................-40C to +85C VH to GND..............................................................-0.3V to +34V VH, EXT to IN............................................................-7V to +0.3V MAX174 AUB ................................................-40C to +125C Junction Temperature......................................................+150C CS, OUT to GND ....................................................-0.3V to +20V Storage Temperature Range .............................-65C to +150C FB, 3/5, REF to GND.....................................-0.3V to (VL + 0.3V) VL to GND...................................................................-0.3V to 6V Lead Temperature (soldering, 10s) ................................+300C Continuous Power Dissipation (T = +70C) A 10-Pin MAX (derate 5.6mW/C above 70C) .............444mW 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 = 5.5V to 36V, 3/5 = GND, I = 0, T = 0C to +85C, unless otherwise noted. Typical values at V = V = IN SHDN LOAD A IN SHDN 36V, T = +25C.) A PARAMETER CONDITIONS MIN TYP MAX UNITS Input Voltage Range 4.5 36 V Supply Current into IN V = V = 5.5V to 36V 90 140 A SHDN IN Shutdown Supply Current SHDN = GND 4 12 A 3/5 = VL 4.85 5.00 5.15 Output Voltage (MAX1744) V 3/5 = GND 3.20 3.30 3.40 OUT Input Current (MAX1744) 3/5 = VL, V = 5V 28 44 A OUT FB Threshold Voltage (MAX1745) Falling edge, hysteresis = 8mV 1.22 1.25 1.28 V FB Input Current (MAX1745) -50 50 nA VH Output Voltage with Respect to IN V = 5.5V to 36V, I = 100A to 20mA -6.0 -5.3 -4.3 V IN VH VL Output Voltage V = 5.5V to 36V, I = 100A to 2mA 4.5 5.0 5.5 V IN VL VL Undervoltage Lockout 2.0 3.0 4.1 V V = V = 2.5V to 18V 85 100 115 CS OUT CS Threshold Voltage mV V = V = V 80 110 150 CS OUT GND V = V = 2.5V to 18V 0 15 25 CS OUT CS Input Current A V = V = V -25 0 CS OUT GND SHDN, 3/5 Logic-High Threshold V = 4.5V to 36V 2.4 V IN SHDN, 3/5 Logic-Low Threshold V = 4.5V to 36V 0.4 V IN 3/5 Input Current SHDN = GND 1A 3/5 = GND 1 SHDN Input Current A V = 36V 12 SHDN EXT Resistance 820 Minimum EXT Off-Time 1.5 2.0 2.5 s Minimum EXT On-Time 0.7 1.0 1.5 s Output Line Regulation Figure 1, 5.5V < V < 36V, I = 1A 5 mV/V IN LOAD Output Load Regulation Figure 1, V = 12V, 30mA < I < 2A 15 mV/A IN LOAD Reference Voltage I = 0 1.22 1.25 1.28 V REF REF Load Regulation 0 I 100A 4 10 mV REF REF Line Regulation V = 4.5V to 36V, I = 0 30 60 V/V IN REF 2 MAX1744/MAX1745