TC120 is a 300 KHz 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 600 mA (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. The TC120 consumes only 55µA (max) of supply current (VOUT = 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 2.5 µA(max), and VOUT 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.
Parameter Name Value
Device Description Step-down Regulator/Controller Combination
SW Reg Output Fixed
Typical Active Supply (µA) 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
Features
Internal Switching Transistor
Supports 600mA Output Current
External Switching Transistor Control for Output Currents of 2A+ 300 KHz
Oscillator Frequency Supports Small Inductor Size
Short Circuit Protection
Built-In Undervoltage Lockout
High (95%, Typ) Efficiency
Automatic Switchover to Current-Saving PFM Mode at Low Output Loads
Automatic Output Capacitor Discharge While in Shutdown
Programmable Soft-Start Time
Power-Saving Shutdown Mode
