The LTC1871-1 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. 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.