LTC1871-1 Wide Input Range, No R SENSE Current Mode Boost, Flyback and SEPIC Controller FEATURES DESCRIPTION n High Ef ciency (No Sense Resistor Required) The LTC 1871-1 is a wide input range, current mode, boost, n Wide Input Voltage Range: 2.5V to 36V yback or SEPIC controller that drives an N-channel power n Current Mode Control Provides Excellent MOSFET and requires very few external components. It Transient Response eliminates the need for a current sense resistor by utilizing n High Maximum Duty Cycle (92% Typ) the power MOSFETs on-resistance, thereby maximizing n 2% RUN Pin Threshold with 100mV Hysteresis ef ciency. Higher output voltage applications are possible n 1% Internal Voltage Reference with the LTC1871-1 by connecting the SENSE pin to a n Ultra Low Pulse Skip Threshold for Wide Input resistor in the source of the power MOSFET. Range Applications The ICs operating frequency can be set with an external n Micropower Shutdown: I = 10A Q resistor over a 50kHz to 1MHz range, and can be synchro- n Programmable Operating Frequency nized to an external clock using the MODE/SYNC pin. (50kHz to 1MHz) with One External Resistor n The LTC1871-1 differs from the LTC1871 by having a Synchronizable to an External Clock Up to 1.3 f OSC n lower pulse skip threshold, making it ideal for applica- User-Controlled Pulse Skip or Burst Mode Operation n tions requiring constant frequency operation at light Internal 5.2V Low Dropout Voltage Regulator n loads. The lower pulse skip threshold also helps maintain Output Overvoltage Protection n constant frequency operation in applications with a wide Capable of Operating with a Sense Resistor for High input voltage range. For applications requiring primary- Output Voltage Applications n to-secondary side isolation, please refer to the LTC1871 Small 10-Lead MSOP Package datasheet. The LTC1871-1 is available in the 10-lead MSOP package. APPLICATIONS L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. n No R is a trademark of Linear Technology Corporation. All other trademarks are the Telecom Power Supplies SENSE property of their respective owners. n Portable Electronic Equipment TYPICAL APPLICATION V IN 3.3V Ef ciency of Figure 1 L1 100 1H D1 90 RUN SENSE Burst Mode V OUT 80 5V OPERATION I V TH IN 7A R C C OUT1 + (10A PEAK) LTC1871-1 70 22k 150F PULSE-SKIP 6.3V FB INTV CC MODE C C1 R1 60 4 C OUT2 6.8nF 12.1k FREQ GATE M1 22F C IN 1% C VCC + 6.3V 50 R2 R MODE/SYNC GND C T 22F C2 4.7F X5R 37.4k 80.6k 6.3V 47pF X5R 2 1% 1% 2 40 GND 18711 F01a 30 C : TAIYO YUDEN JMK325BJ226MM D1: MBRB2515L IN 0.001 0.01 0.1 1 10 C : PANASONIC EEFUEOJ151R L1: SUMIDA CEP125-H 1R0MH OUT1 OUTPUT CURRENT (A) C : TAIYO YUDEN JMK325BJ226MM M1: FAIRCHILD FDS7760A OUT2 18711 F01b Figure 1. High Ef ciency 3.3V Input, 5V Output Boost Converter (Bootstrapped) 18711fb 1 EFFICIENCY (%)LTC1871-1 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW V Voltage ............................................... 0.3V to 36V IN RUN 1 10 SENSE INTV Voltage ............................................ 0.3V to 7V CC I 2 9 V TH IN FB 3 8 INTV INTV Output Current .......................................... 50mA CC CC FREQ 4 7 GATE GATE Voltage ............................ 0.3V to V + 0.3V MODE/ 5 6 GND INTVCC SYNC I , FB Voltages ....................................... 0.3V to 2.7V MS PACKAGE TH 10-LEAD PLASTIC MSOP RUN, MODE/SYNC Voltages ....................... 0.3V to 7V T = 125C, = 120C/W JMAX JA FREQ Voltage ............................................ 0.3V to 1.5V SENSE Pin Voltage .................................... 0.3V to 36V Operating Junction Temperature Range (Note 2) LTC1871E-1 ......................................... 40C to 85C LTC1871I-1 ........................................ 40C to 125C Junction Temperature (Note 3) ............................ 125C Storage Temperature Range ................... 65C to 150C Lead Temperature (Soldering, 10 sec) .................. 300C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC1871EMS-1 PBF LTC1871EMS-1 TRPBF LTCTV 10-Lead Plastic MSOP 40C to 85C LTC1871IMS-1 PBF LTC1871IMS-1 TRPBF LTCTV 10-Lead Plastic MSOP 40C to 125C LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC1871EMS-1 LTC1871EMS-1 TR LTCTV 10-Lead Plastic MSOP 40C to 85C LTC1871IMS-1 LTC1871IMS-1 TR LTCTV 10-Lead Plastic MSOP 40C to 125C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. For more information on lead free part marking, go to: