LINEAR TECHNOLOGY LTC1871 1871fc Wide Input Range, No RSENSE Current Mode Boost, Flyback and SEPIC Controller

LTC1871 TM

Wide Input Range, No RSENSE

Current Mode Boost, Flyback and SEPIC Controller

FEATURES DESCRIPTIO High Efficiency (No Sense Resistor Required) The LTC®1871 is a wide input range, current mode, boost, Wide Input Voltage Range: 2.5V to 36V flyback or SEPIC controller that drives an N-channel Current Mode Control Provides Excellent power MOSFET and requires very few external compo-

Transient Response nents. Intended for low to medium power applications, it High Maximum Duty Cycle (92% Typ) eliminates the need for a current sense resistor by utiliz- ±2% RUN Pin Threshold with 100m V Hysteresis ing the power MOSFET’s on-resistance, thereby maximiz- ±1% Internal Voltage Reference ing efficiency.

Micropower Shutdown: IQ = 10µA

The IC’s operating frequency can be set with an external

Programmable Operating Frequency

resistor over a 50k Hz to 1MHz range, and can be synchro-

(50k Hz to 1MHz) with One External Resistor

nized to an external clock using the MODE/SYNC pin.

Synchronizable to an External Clock Up to 1.3 × f OSC

Burst Mode operation at light loads, a low minimum

User-Controlled Pulse Skip or Burst Mode® Operation

operating supply voltage of 2.5V and a low shutdown

Internal 5.2V Low Dropout Voltage Regulator

quiescent current of 10µA make the LTC1871 ideally

Output Overvoltage Protection

suited for battery-operated systems.

Capable of Operating with a Sense Resistor for High

Output Voltage Applications For applications requiring constant frequency operation, Small 10-Lead MSOP Package Burst Mode operation can be defeated using the MODE/ SYNC pin. Higher output voltage boost, SEPIC and fly- back applications are possible with the LTC1871 by

EF FI CI EN CY

APPLICATIO S

connecting the SENSE pin to a resistor in the source of the power MOSFET.

Telecom Power Supplies Portable Electronic Equipment The LTC1871 is available in the 10-lead MSOP package.

, LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.

TYPICAL APPLICATIO

VIN 3.3V

L1 Efficiency of Figure 1

RUN SENSE VOUT

Burst Mode

ITH VIN OPERATION

RC COUT1

LTC1871 (10A PEAK)

22k 150µF FB INTVCC 6.3V PULSE-SKIP

CC1 R1 ×4 COUT2

6.8n F 12.1k FREQ GATE M1 22µF

1% CVCC 6.3V

CC2 R2 RT MODE/SYNC GND 22µF

GND 1871 F01a

CIN: TAIYO YUDEN JMK325BJ226MM D1: MBRB2515L COUT1: PANASONIC EEFUEOJ151R L1: SUMIDA CEP125-H 1R0MH 0.001 0.01 0.1 COUT2: TAIYO YUDEN JMK325BJ226MM M1: FAIRCHILD FDS7760A

OUTPUT CURRENT (A)

Figure 1. High Efficiency 3.3V Input, 5V Output Boost Converter (Bootstrapped)

1871fc