General Description

The TC105 is a step-down (Buck) switching controller that furnishes output currents of up to 1A (max) while delivering a typical efficiency of 92%. The TC105 normally operates in pulse width modulation mode (PWM), but automatically switches to pulse frequency modulation (PFM) at low output loads for greater efficiency. Oscillator frequency is 300kHz, allowing use of small (22µH) inductors. Supply current draw is only 102µA (max), and is reduced to less than 0.5µA when the SHDN input is brought low. Regulator operation is suspended during shutdown. The TC105 accepts a maximum input voltage of 10V.

Features

• 57µA (Typ) Supply Current

• 1A Output Current

• 0.5µA Shutdown Mode

• 300kHz Switching Frequency for Small Inductor Size

• Programmable Soft-Start

• 92% Typical Efficiency

• Small Package: 5-Pin SOT-23A

Applications

• Palmtops

• Battery-Operated Systems

• Portable Instruments

• Positive LCD Bias Generators

• Portable Communicators

• Hand-Held Scanners

• 5V to 3V Down Converters