Features

• OBSOLETE:  For Information Purposes Only.  Contact Linear Technology for Potential Replacement.
• Accurate Preset +5V Output
• Up to 90% Efficiency
• Optional Burst Mode for Light Loads
• Can be Used with Many LTC Switching ICs
• Accurate Ultra-Low-Loss Current Limit
• Operates with Inputs from 6V to 30V
• Shutdown Mode Draws Only 15µA
• Uses Small 50µH Inductor

Typical Application

Description

The LT1432 is a control chip designed to operate with the LT1170/LT1270 family of switching regulators to make a very high efficiency 5V step-down (buck) switching regulator. A minimum of external components is needed.

Included is an accurate current limit which uses only 60mV sense voltage and uses "free" PC board trace material for the sense resistor. Logic controlled electronic shutdown mode draws only 15µA battery current. The switching regulator operates down to 6V input.

The LT1432 has a logic controlled "burst" mode to achieve high efficiency at very light load currents (0 to 100mA) such as memory keep-alive. In normal switching mode, the standby power loss is about 60mW, limiting efficiency at light loads. In burst mode, standby loss is reduced to approximately 15mW. Output current in this mode is typically in the 5mA to 100mA range.

The LT1432 is available in 8-pin surface mount and DIP packages. The LT1170/LT1270 family will also be available in a surface mount version of the 5-pin TO-220 package. For 3.3V versions contact Linear Technology Corporation.