LT1950

· 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 V_IN 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 • f_OSC
· Current Mode Control
· Small 16-Pin SSOP Package

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

BOOST ........................................................ 0.3V to 35V
V_IN, V_IN2, SHDN .......................................... 0.3V to 25V
FB, SYNC, VSEC ............................................ 0.3V to 6V
COMP, BLANK ............................................ 0.3V to 3.5V
SLOPE ....................................................... 0.3V to 2.5V
ISENSE ......................................................... 0.3V to 1V
R_OSC .................................................................... 50mA
V_REF ..................................................................... 10mA
Operating Junction Temperature Range
LT1950EGN/LT1950IGN (Notes 2, 5) ... 40°C to 125°C
Storage Temperature Range ...............65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C

The LT^®1950 is a wide input range, forward, boost, flyback and SEPIC controller that drives an N-channel powerMOSFET 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.