LTC1871 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 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. In- Transient Response tended for low to medium power applications, it eliminates n High Maximum Duty Cycle (92% Typ) the need for a current sense resistor by utilizing the power n 2% RUN Pin Threshold with 100mV Hysteresis MOSFETs on-resistance, thereby maximizing ef ciency. n 1% Internal Voltage Reference 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 syn- n Programmable Operating Frequency chronized to an external clock using the MODE/SYNC (50kHz to 1MHz) with One External Resistor pin. Burst Mode operation at light loads, a low minimum n Synchronizable to an External Clock Up to 1.3 f OSC operating supply voltage of 2.5V and a low shutdown n User-Controlled Pulse Skip or Burst Mode Operation quiescent current of 10A make the LTC1871 ideally suited n Internal 5.2V Low Dropout Voltage Regulator for battery-operated systems. n Output Overvoltage Protection n For applications requiring constant frequency opera- Capable of Operating with a Sense Resistor for tion, Burst Mode operation can be defeated using the High Output Voltage Applications n MODE/SYNC pin. Higher output voltage boost, SEPIC Small 10-Lead MSOP Package and yback applications are possible with the LTC1871 by connecting the SENSE pin to a resistor in the source APPLICATIONS of the power MOSFET. n Telecom Power Supplies The LTC1871 is available in the 10-lead MSOP package. n Portable Electronic Equipment L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. No R is a trademark of Linear Technology Corporation. All other trademarks are the SENSE property of their respective owners. TYPICAL APPLICATION V IN 3.3V Ef ciency of Figure 1 L1 100 1H D1 90 RUN SENSE Burst Mode V OUT 80 OPERATION 5V I V TH IN 7A R C OUT1 C + (10A PEAK) LTC1871 70 22k 150F PULSE-SKIP 6.3V FB INTV CC MODE C C1 R1 4 C 60 OUT2 6.8nF FREQ GATE M1 12.1k 22F C IN 1% C 6.3V VCC + R2 R 50 T MODE/SYNC GND 22F C C2 4.7F X5R 37.4k 80.6k 47pF 6.3V X5R 2 1% 1% 2 40 GND 1871 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 1871 F01b Figure 1. High Ef ciency 3.3V Input, 5V Output Boost Converter (Bootstrapped) 1871fe 1 EFFICIENCY (%)LTC1871 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 I 2 9 V TH IN CC FB 3 8 INTV CC INTV Output Current .......................................... 50mA CC FREQ 4 7 GATE MODE/ 5 6 GND GATE Voltage ............................ 0.3V to V + 0.3V INTVCC SYNC MS PACKAGE I , FB Voltages ....................................... 0.3V to 2.7V 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 Temperature Range (Note 2) LTC1871E ............................................. 40C to 85C LTC1871I............................................ 40C to 125C LTC1871H .......................................... 40C to 150C Junction Temperature (Note 3) LTC1871E/LTC1871I ......................................... 125C LTC1871H .........................................................150C 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 PBF LTC1871EMS TRPBF LTSX 10-Lead Plastic MSOP 40C to 85C LTC1871IMS PBF LTC1871IMS TRPBF LTBFC 10-Lead Plastic MSOP 40C to 125C LTC1871HMS PBF LTC1871HMS TRPBF LTCXS 10-Lead Plastic MSOP 40C to 150C LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC1871EMS LTC1871EMS TR LTSX 10-Lead Plastic MSOP 40C to 85C LTC1871IMS LTC1871IMS TR LTBFC 10-Lead Plastic MSOP 40C to 125C LTC1871HMS LTC1871HMS TR LTCXS 10-Lead Plastic MSOP 40C to 150C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. For more information on lead free part marking, go to: