TC120

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




Application

• Portable Test Equipment
• Local Logic Supplies
• Portable Audio Systems
• Portable Scanners
• Palmtops
• Electronic Organizers




Pinout






Specifications

Power Supply Voltage (V_IN)................................. -0.3V to +12V
Voltage on V_OUT Pin ............................................ -0.3V to +12V
Voltage on LX, Boost Pins............... (V_IN 12V) to (V_IN + 0.3V)
Voltage on EXT1, EXT2, SHDN Pins.......... (-0.3V) to (V_IN + 0.3V)
L_X Pin Current ............................................................ 700mA pk
EXT1, EXT2 Pin Current ...................................................±50mA
Continuous Power Dissipation ........................................300mW
Operating Temperature Range..............................-40 to +85
Storage Temperature Range ............................. -40 to +150

*Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These
are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operation sections of the specifications is not implied. Exposure to Absolute Maximum Rating conditions for
extended periods may affect device reliability.

Parameter NameValueDevice DescriptionStep-down Regulator/Controller CombinationSW Reg OutputFixedTypical Active Supply (A)71Switching Frequency (kHz)300Output Current (mA)600Output Voltage (V)3.0, 3.3, 5.0Input Voltage Range (V)2.2 to 10

Parameter Name	Value
Device Description	Step-down Regulator/Controller Combination
SW Reg Output	Fixed
Typical Active Supply (A)	71
Switching Frequency (kHz)	300
Output Current (mA)	600
Output Voltage (V)	3.0, 3.3, 5.0
Input Voltage Range (V)	2.2 to 10

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 (V_IN = 5V, V_OUT = 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.

The TC120 consumes only 55µA (max) of supply current (V_OUT = 3.3V) and can be placed in shutdown mode by bringing the shutdown input (SHDN) low. During shutdown, the regulator is disabled, supply current is reduced to 2.5µA (max), and V_OUT is internally pulled to ground, discharging the output capacitor. Normal operation resumes when SHDN is brought high. Other features include a built-in undervoltage lockout (UVLO), an externally programmable soft start time, and output short circuit protection. The TC120 operates from a maximum input voltage of 10V and is available in a low-profile 8-Pin SOP package.