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LTC1871-1 - Wide Input Range, No RSENSE Current Mode Boost, Flyback and SEPIC Controller

The LTC1871-1 is a wide input range, current mode, boost, flyback or SEPIC controller that drives an Nchannel power MOSFET and requires very few external components. It eliminates the need for a current sense resistor by utilizing the power MOSFET’s on-resistance, thereby maximizing efficiency. Higher output voltage applications are possible with the LTC1871-1 by connecting the SENSE pin to a resistor in the source of the power MOSFET.

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.

The LTC1871-1 differs from the LTC1871 by having a lower pulse skip threshold, making it ideal for applications requiring constant frequency operation at light loads. The lower pulse skip threshold also helps maintain constant frequency operation in applications with a wide input voltage range. For applications requiring primaryto- secondary side isolation, please refer to the LTC1871 datasheet.

The LTC1871-1 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 Ultra Low Pulse Skip Threshold for Wide Input Range Applications 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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