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LTC1871 - Wide Input Range, No RSENSE Current Mode Boost, Flyback and SEPIC Controller

The LTC1871 is a wide input range, current mode, boost, flyback or SEPIC controller that drives an N-channel power MOSFET and requires very few external components. Intended for low to medium power applications, it eliminates the need for a current sense resistor by utilizing the power MOSFET’s on-resistance, thereby maximizing efficiency.

The IC’s operating frequency can be set with an external resistor over a 50kHz to 1MHz range, and can be synchronized to an external clock using the MODE/SYNC pin. Burst Mode operation at light loads, a low minimum operating supply voltage of 2.5V and a low shutdown quiescent current of 10μA make the LTC1871 ideally suited for battery-operated systems.

For applications requiring constant frequency operation, Burst Mode operation can be defeated using the MODE/ SYNC pin. Higher output voltage boost, SEPIC and flyback applications are possible with the LTC1871 by connecting the SENSE pin to a resistor in the source of the power MOSFET.

The LTC1871 is available in the 10-lead MSOP package.

Features High Efficiency (No Sense Resistor Required) Wide Input Voltage Range: 2.5V to 36V Current Mode Control Provides Excellent Transient Response High Maximum Duty Cycle (92% Typ) ±2% RUN Pin Threshold with 100mV Hysteresis ±1% Internal Voltage Reference Micropower Shutdown: IQ = 10μA Programmable Operating Frequency (50kHz to 1MHz) with One External Resistor Synchronizable to an External Clock Up to 1.3 × fOSC User-Controlled Pulse Skip or Burst Mode® Operation Internal 5.2V Low Dropout Voltage Regulator Output Overvoltage Protection Capable of Operating with a Sense Resistor for High Output Voltage Applications Small 10-Lead MSOP Package Typical Application

Applications Telecom Power Supplies Portable Electronic Equipment Packaging

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