MAX17112 19-4393 Rev 0 12/08 High-Performance, Step-Up, DC-DC Converter General Description Features The MAX17112 is a high-performance, step-up, DC-DC Input Overvoltage Protection converter that provides a regulated supply voltage for active-matrix thin-film transistor (TFT) liquid-crystal dis- Adjustable Output from V to 20V IN plays (LCDs). The MAX17112 incorporates current- 2.6V to 5.5V Input Supply Range mode, fixed-frequency (1MHz), pulse-width modulation (PWM) circuitry with a built-in, n-channel power MOSFET Input Supply Undervoltage Lockout to achieve high efficiency and fast-transient response. The input overvoltage protection (OVP) function pre- 1MHz Fixed Switching Frequency vents damage to the MAX17112 from an input surge Programmable Soft-Start voltage (up to 24V). The high switching frequency (1MHz) allows the use of Small 10-Pin, TDFN Package ultra-small inductors and low-ESR ceramic capacitors. Thermal-Overload Protection The current-mode architecture provides fast-transient response to pulsed loads. A compensation pin (COMP) gives users flexibility in adjusting loop dynamics. The internal MOSFET can generate output voltages up to Ordering Information 20V from an input voltage between 2.6V and 5.5V. Soft-start slowly ramps the input current and is pro- PART TEMP RANGE PIN-PACKAGE grammable with an external capacitor. The MAX17112 MAX17112ETB+ -40C to +85C 10 TDFN-EP* is available in a 10-pin TDFN package. +Denotes a lead(Pb)-free/RoHS-compliant package. Applications *EP = Exposed pad. Notebook Computer Displays LCD Monitor Panels Simplified Operating Circuit Pin Configuration V IN V OUT 2.6V TO 5.5V TOP VIEW 67 LX LX + COMP 1 10 SS 8 2 FB IN FB29 SHDN MAX17112 V 3 8 IN L 9 MAX17112 5 GND SHDN GND 4 7 LX 3 4 V GND L *EP GND56 LX 10 1 COMP SS GND TDFN EP 3mm 3mm *EXPOSED PAD 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 AVAILABLEHigh-Performance, Step-Up, DC-DC Converter ABSOLUTE MAXIMUM RATINGS LX to GND ..............................................................-0.3V to +24V Continuous Power Dissipation (T = +70C) A IN to GND...............................................................-0.3V to +24V 10-Pin 3mm x 3mm Thin TDFN SHDN, V to GND..................................................-0.3V to +7.5V (derate 24.4mW/C above +70C) ............................1951mW L COMP, SS, FB to GND..................................-0.3V to (V + 0.3V) Operating Temperature Range ...........................-40C to +85C L LX Switch Maximum Continuous RMS Current.....................3.2A Junction Temperature......................................................+150C Storage Temperature Range .............................-65C to +150C 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. ELECTRICAL CHARACTERISTICS (V = 3V, T = 0C to +85C, unless otherwise noted.) L A PARAMETER CONDITIONS MIN TYP MAX UNITS V < 18V 2.6 5.5 V OUT IN Supply Range 18V < V < 20V 4.0 5.5 V OUT OVP Threshold V rising 6.2 6.6 7 V IN OVP Switch Resistance 8 12 20 Output Voltage Range 20 V VL Undervoltage-Lockout V rising typical hysteresis is 50mV LX remains off L 2.30 2.45 2.57 V Threshold below this level V = 1.3V, not switching 0.3 0.6 FB IN Quiescent Current mA V = 1.0V, switching 1.5 2.5 FB IN Shutdown Supply Current SHDN = GND 160 250 A Temperature rising 160 Thermal Shutdown C Hysteresis 20 ERROR AMPLIFIER Feedback Voltage Level to produce V = 1.24V 1.23 1.24 1.25 V COMP FB Input Bias Current V = 1.24V 50 125 225 nA FB FB Line Regulation Level to produce V = 1.24V, 2.6V < V < 5.5V 0.05 0.15 %/V COMP IN Transconductance 110 300 450 S Voltage Gain 2400 V/V Shutdown FB Input Voltage SHDN = GND 0.05 0.10 0.15 V OSCILLATOR Frequency (f) 800 1000 1200 kHz OSC Maximum Duty Cycle 89 92 95 % n-CHANNEL MOSFET Current Limit V = 1V, 75% duty cycle, V = 5V 3.9 4.6 5.3 A FB L V = 5V (typ value at T = +25C) (Note 1) 110 170 L A On-Resistance m V = 3V (typ value at T = +25C) (Note 1) 135 210 L A Leakage Current V = 20V 12 25 A LX Current-Sense Transresistance V = 5V 0.09 0.15 0.25 V/A L 2 MAX17112