LTC3121Linear Technology Corp. announces the LTC3121, a 3 MHz current mode, synchronous boost DC/DC converter with integrated output disconnect. Its internal 1.5 A switches deliver output voltages as high as 15 V from an input voltage range of 1.8 V at start-up (0.5 V when running) to 5.5 V, making it ideal for battery or standard 3.3 V and 5 V power sources. The LTC3121 delivers up to 40 0mA of continuous output current at 1 2V from a 5 V input. Furthermore, its 1.5A current limit makes it well suited for input current constrained applications such as PCI Express while minimizing the size of the required externals. Pin-selectable Burst Mode® operation lowers quiescent current to only 25µA, providing extended battery run time in handheld applications. The combination of its thermally enhanced 3mm x 4mm DFN-12 package and a constant switching frequency of up to 3MHz enables the designer to balance PCB solution size with required efficiency.

The LTC3121 has internal synchronous switches with an RDS(ON) of only 121mΩ (N-channel) and 188mΩ (P-channel) to deliver efficiencies as high as 95%. Output disconnect allows the output voltage to be completely discharged in shutdown and also eliminates large inrush currents during start-up, minimizing stress on the input supply. The LTC3121 also regulates the output voltage when the input voltage exceeds the output voltage, making the device compatible with any battery chemistry. For applications demanding the lowest possible noise operation, the LTC3121 can be set via an external pin to operate in constant PWM mode. Additional features include external synchronization, output overvoltage protection and robust short-circuit protection.

The LTC3121EDE is available from stock in a 12-lead 3mm x 4mm DFN. 1,000-piece pricing starts at $2.33 each. An industrial-grade version, the LTC3121IDE, is guaranteed to operate over the -40°C to 125°C operating junction temperature range and is priced at $2.73 each in 1,000-piece quantities. All versions are available from stock. For more information, visit

Summary of Features: LTC3121

  • VIN Range: 1.8V to 5.5V, 500mV after Start-Up
  • Output Voltage Range: 2.2V to 15V
  • 400mA Output Current for
    VIN = 5V & VOUT = 12V
  • Output Disconnects from Input when Shut Down
  • Synchronous Rectification: Up to 95% Efficiency
  • Inrush Current Limit
  • Up to 3MHz Adjustable Switching Frequency Synchronizable to External Clock
  • Selectable Burst Mode® Operation: 25µA IQ
  • Output Overvoltage Protection
  • Soft-Start
  • <1µA IQ in Shutdown
  • 12-Lead, 3mm x 4mm x 0.75mm Thermally Enhanced DFN Package

The USA list pricing shown is for budgetary use only. International prices may differ due to local duties, taxes, fees and exchange rates.