POWER LOSS (W) LTC3121 15V, 1.5A Synchronous Step-Up DC/DC Converter with Output Disconnect Fea T Descrip T n V Range: 1.8V to 5.5V, 500mV After Start-Up The LTC 3121 is a synchronous step-up DC/DC converter IN n Output Voltage Range: 2.2V to 15V with true output disconnect and inrush current limiting. The n 400mA Output Current for V = 5V and V = 12V 1.5A current limit along with the ability to program output IN OUT n Output Disconnects from Input When Shut Down voltages up to 15V makes the LTC3121 well suited for a n Synchronous Rectification: Up to 95% Efficiency variety of demanding applications. Once started, operation n Inrush Current Limit will continue with inputs down to 500mV, extending run n Up to 3MHz Adjustable Switching Frequency time in many applications. Synchronizable to External Clock The LTC3121 features output disconnect in shutdown, n Selectable Burst Mode Operation: 25A I Q dramatically reducing input power drain and enabling n Output Overvoltage Protection V to completely discharge. Adjustable PWM switching OUT n Soft-Start from 100kHz to 3MHz optimizes applications for highest n <1A I in Shutdown Q efficiency or smallest solution footprint. The oscillator n 12-Lead, 3mm 4mm Thermally Enhanced DFN can also be synchronized to an external clock for noise Package sensitive applications. Selectable Burst Mode operation reduces quiescent current to 25A, ensuring high efficiency a T across the entire load range. An internal soft-start limits inrush current during start-up. n PCI Express Cards/Systems n Piezo Actuators Other features include a <1A shutdown current and robust n Small DC Motors protection under short-circuit, thermal overload, and output n 12V Analog Rail From Battery, 5V, or Backup Capacitor overvoltage conditions. The LTC3121 is offered in a low profile 12-lead (3mm 4mm 0.75mm) DFN package. L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks and ThinSOT is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Typical a T 5V to 12V Synchronous Boost Converter with Output Disconnect Efficiency Curve 100 10 6.8H V IN Burst Mode 90 5V OPERATION 80 SW V OUT 70 V V 12V IN OUT 1 PWM 400mA LTC3121 60 SD OFF ON 100nF 4.7F 50 BURST PWM PWM/SYNC CAP 1.02M 40 RT FB 22F 0.1 30 PWM POWER LOSS V V 113k CC C 20 SGND PGND 210k 10 57.6k 10pF 0 0.01 4.7F 390pF 0.01 0.1 1 10 100 600 LOAD CURRENT (mA) 3121 TA01b 3121 TA01a 3121fa 1 For more information www.linear.com/LTC3121 EFFICIENCY (%) ion pplica ions pplica ion uresLTC3121 a Te Maxi Mu M r a T p in c F T (Note 1) V Voltage .................................................. 0.3V to 6V IN TOP VIEW V Voltage ............................................ 0.3V to 18V OUT SW Voltage (Note 2) .................................. 0.3V to 18V SW 1 12 CAP SW Voltage (Pulsed < 100ns) (Note 2) ....... 0.3V to 19V PGND 2 11 V OUT V , RT Voltage .......................................... 0.3V to V V 3 10 SGND IN C CC 13 PGND PWM/SYNC 4 9 SD CAP Voltage V 5 8 FB V < 5.7V ............................0.3V to (V + 0.3V) CC OUT OUT RT 6 7 V 5.7V V 11.7V...... (V 6V) to (V + 0.3V) C OUT OUT OUT V > 11.7V .................................(V 6V) to 12V OUT OUT DE PACKAGE 12-LEAD (4mm 3mm) PLASTIC DFN All Other Pins ............................................... 0.3V to 6V T = 125C, = 43C/W (NOTE 5), = 5C/W JMAX JA JC Operating Junction Temperature Range EXPOSED PAD (PIN 13) IS PGND, MUST BE SOLDERED TO PCB FOR RATED THERMAL PERFORMANCE (Notes 3, 4) ............................................ 40C to 125C Storage Temperature Range .................. 65C to 150C o r Der i n F Ma T