LT1961

` 1.5A Switch in a Small MSOP Package
` Constant 1.25MHz Switching Frequency
` Wide Operating Voltage Range: 3V to 25V
` High Efficiency 0.2 Switch
` 1.2V Feedback Reference Voltage
` ±2% Overall Output Voltage Tolerance
` Uses Low Profile Surface Mount External Components
` Low Shutdown Current: 6mA
` Synchronizable from 1.5MHz to 2MHz
` Current-Mode Loop Control
` Constant Maximum Switch Current Rating at All Duty Cycles*
` Thermally Enhanced Exposed Pad Package

· DSL Modems
· Portable Computers
· Battery-Powered Systems
· Distributed Power

Input Voltage ........................................................ 25V
Switch Voltage ...................................................... 35V
SHDN Pin ............................................................... 25V
FB Pin Current ...................................................... 1mA
SYNC Pin Current .................................................. 1mA
Operating Junction Temperature Range (Note 2)
LT1961E ........................................ 40°C to 125°C
Storage Temperature Range ......... 65°C to 150°C
Lead Temperature (Soldering, 10 sec).............. 300°C

The LT^®1961 is a 1.25MHz monolithic boost switching regulator. A high efficiency 1.5A, 0.2 switch is included on the die together with all the control circuitry required to complete a high frequency, current-mode switching regulator. Current-mode control provides fast transient response and excellent loop stability.

New design techniques of LT1961 achieve high efficiency at high switching frequencies over a wide operating voltage range.
A low dropout internal regulator maintains consistent performance over a wide range of inputs from 24V systems to Li-Ion batteries. An operating supply current of 1A maintains high efficiency, especially at lower output currents. Shutdown reduces quiescent current to 6A. Maximum switch current remains constant at all duty cycles. Synchronization allows an external logic level signal to increase the internal oscillator from 1.5MHz to 2MHz.

The LT1961 is available in an exposed pad, 8-pin MSOP package. Full cycle-by-cycle switch current limit protection and thermal shutdown are provided. High frequency operation allows the reduction of input and output filtering components and permits the use of chip inductors.