A simple 5V boost converter using LTC3440 shown here. LTC3440 is a high efficiency DC to DC converter that can be operated from input voltages below, above or equal to the output voltage. As for the synchronous rectification, LTC3440 delivers up to 96% efficiency and up to 600 mA output current is guaranteed. The IC has built an oscillator whose frequency synchronized whose frequency can be adjusted from 300 kHz to 2 MHz
The LTC3440 circuit is connected as a boost converter capable of delivering 5V output 5V @ 300mA constant input voltage of 2.7 to 4.2 V. The resistor R4 is used to set the oscillator frequency, while the resistors R1 and R2 are used to adjust the output to 5 volts. Resistance R3 and capacitor C1 form a frequency compensation network, while C3 serves as an input bypass capacitor. S1 is the stop switch and capacitor C2 is the output filter.
