DESCRIPTION
The LTC®1436A/LTC1437A are synchronous step-down switching regulator controllers that drive external N-channel power MOSFETs in a phase lockable, fixed frequency architecture. The Adaptive PowerTM output stage selectively drives two N-channel MOSFETs at frequencies up to 400kHz while reducing switching losses to maintain high efficiencies at low output currents.

FEATURES
■ Maintains Constant Frequency at Low Output Currents
■ Dual N-Channel MOSFET Synchronous Drive
■ Programmable Fixed Frequency (PLL Lockable)
■ Wide VIN Range: 3.5V to 36V Operation
■ Low Minimum On-Time (≤300ns) for High Frequency, Low Duty Cycle Applications
■ Very Low Dropout Operation: 99% Duty Cycle
■ Low Dropout, 0.5A Linear Regulator for CPU I/O or Low Noise Audio Supplies
■ Built-In Power-On Reset Timer
■ Programmable Soft Start
■ Low-Battery Detector
■ Remote Output Voltage Sense
■ Foldback Current Limiting (Optional)
■ Pin Selectable Output Voltage
■ Logic Controlled Micropower Shutdown: IQ < 25µA
■ Output Voltages from 1.19V to 9V
■ Available in 24-Lead Narrow SSOP and 28-Lead SSOP Packages

APPLICATIONS
■ Notebook and Palmtop Computers, PDAs
■ Cellular Telephones and Wireless Modems
■ Portable Instruments
■ Battery-Operated Devices
■ DC Power Distribution Systems