DESCRIPTION
The LTC1157 dual 3.3V micropower MOSFET gate driver makes it possible to switch either supply or ground reference loads through a low RDS(ON) N-channel switch (N-channel switches are required at 3.3V because P-channel MOSFETs do not have guaranteed RDS(ON) with VGS ≤ 3.3V). The LTC1157 internal charge pump boosts the gate drive voltage 5.4V above the positive rail (8.7V above ground), fully enhancing a logic level N-channel switch for 3.3V high-side applications and a standard N-channel switch for 3.3V low-side applications. The gate drive voltage at 5V is typically 8.8V above supply (13.8V above ground), so standard N-channel MOSFET switches can be used for both high-side and low-side applications.

FEATURES
■ Allows Lowest Drop 3.3V Supply Switching
■ Operates on 3.3V or 5V Nominal Supplies
■ 3 Microamps Standby Current
■ 80 Microamps ON Current
■ Drives Low Cost N-Channel Power MOSFETs
■ No External Charge Pump Components
■ Controlled Switching ON and OFF Times
■ Compatible with 3.3V and 5V Logic Families
■ Available in 8-Pin SOIC

APPLICATIONS
■ Notebook Computer Power Management
■ Palmtop Computer Power Management
■ P-Channel Switch Replacement
■ Battery Charging and Management
■ Mixed 5V and 3.3V Supply Switching
■ Stepper Motor and DC Motor Control
■ Cellular Telephones and Beepers