Design of a 5V-output boost DC-DC converter with improved protection functions for battery-operated devices

In this paper, a step-up dc-dc converter for mobile device applications is proposed. The converter is operated with 1 MHz high switching frequency. The power stage of converter includes an inductor, an output capacitor, MOS transistors and feedback resistors for control loop. The control stage consists of an error amplifier, comparator, a ramp generator for PWM block, bandgap reference and soft start block with power transistor. Also, the circuit includes protection block such as over voltage protection (OVP), under voltage lock out (UVLO) and thermal shutdown (TSD) block. The proposed step-up converter has been designed with a 0.18 um CMOS process technology. Simulation results show an output voltage of 5 V with a ripple of 40 mV at the output current of 100 mA for an input voltage of 3.3 V.