General Description

TC120 is a 300kHz PFM/PWM step-down (Buck) DC/DC regulator/controller combination for use in systems

operating from two or more cells, or in line-powered applications. It uses PWM as the primary modulation scheme, but automatically converts to PFM at low output loads for greater efficiency. It requires only an external inductor, Schottky diode, and two capacitors to implement a step-down converter having a maximum output current of 600mA (VIN= 5V, VOUT= 3.3V). An external switching transistor (P-channel MOSFET) can be added to increase output current capability to support output loads of 2A or more.

Features

• Internal Switching Transistor Supports 600mA Output Current

• External Switching Transistor Control for Output Currents of 2A+

• 300kHz Oscillator Frequency Supports Small Inductor Size

• Short Circuit Protection

• Built-In Undervoltage Lockout

• 95% Typical Efficiency

• Automatic Switchover to Current-Saving PFM Mode at Low Output Loads

• Automatic Output Capacitor Discharge While in Shutdown

• Programmable Soft-Start

• Power-Saving Shutdown Mode

• Small 8-Pin SOP Package

Applications

• Portable Test Equipment

• Local Logic Supplies

• Portable Audio Systems

• Portable Scanners

• Palmtops

• Electronic Organizers