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LT1950 - Single Switch PWM Controller with Auxiliary Boost Converter

The LT1950 is a wide input range, forward, boost, flyback and SEPIC controller that drives an N-channel power MOSFET with few external components required.

A resistor programmable duty cycle clamp can be used to generate a volt-second clamp for forward converter applications. An internal boost switcher is available for creating a separate supply for the output gate driver, allowing 10V gate drive from input voltages as low as 3V. The LT1950’s operating frequency can be set with an external resistor over a 100kHz to 500kHz range and a SYNC pin allows the part to be synchronized to an external clock. Additional programmability exists for leading edge blanking and slope compensation.

A fast current sense comparator achieves 60ns current sense delay and the error amplifier is a true voltage mode error amplifier, allowing a wide range of compensation networks. An accurate shutdown pin with programmable hysteresis is available for undervoltage lockout and shutdown. The LT1950 is available in a small 16-Pin SSOP package.

Features Wide Input Range: 3V to 25V Programmable Volt-Second Clamp Output Power Levels from 25W to 500W Auxiliary Boost Converter Provides 10V Gate Drive from VIN as Low as 3V Programmable Operating Frequency (100kHz to 500kHz) with One External Resistor Programmable Slope Compensation Programmable Leading Edge Blanking ±2% Internal 1.23V Reference Accurate Shutdown Pin Threshold with Programmable Hysteresis 60ns Current Sense Delay 2.5V Auxiliary Reference Output Synchronizable to an External Clock up to 1.5 • fOSC Current Mode Control Small 16-Pin SSOP Package Typical Application

Applications Telecom Power Supplies Automotive Power Supplies Portable Electronic Equipment Isolated and Nonisolated DC/DC Converters Packaging

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