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

Description

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.