2.5-A, 15-V synchronous boost regulator offers 95 percent efficiency

October 19, 2012 // By Paul Buckley
Linear Technology Corporation has introduced a 3 MHz current-mode, synchronous boost DC/DC converter with integrated output disconnect.

The LTC3122’s internal 2.5 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 LTC3122 can deliver up to 800 mA of continuous output current at 12 V from a 5 V input. Pin-selected Burst Mode operation lowers quiescent current to only 25 µA, providing extended battery run time in handheld applications. The combination of its thermally enhanced 3 mm x 4 mm DFN-12 (or MSOP-12) package and a constant switching frequency of up to 3 MHz enables the designer to balance PCB solution size with required efficiency.

The LTC3122 has internal synchronous switches with an RDS(ON) of only 121 mOhm (N-channel) and 188 mOhm (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 LTC3122 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 LTC3122 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 LTC3122 is an ideal solution for boost applications requiring outputs up to 15 V, where high efficiency, small solution size and high reliability are defining factors.

Availability and Pricing

LTC3122EDE and LTC3122EMSE are both available from stock in 12-lead 3 mm x 4 mm DFN or thermally enhanced MSOP packages, respectively. 1,000-piece pricing starts at $2.33 each. Industrial-grade versions, the LTC3122IDE and LTC3122IMSE, are guaranteed to operate over the -40 to 125°C operating junction temperature range and are priced at $2.73 each in 1,000-piece quantities. All versions are available from