Low-cost 3.7V to 5V-6V DC to DC converter

This DC-to-DC step-up converter circuit transforms a lower input voltage of 3.6V to 3.7V from a single-cell Li-ion battery into higher regulated output levels of 5V, 5.3V, and 6V. At the heart of the circuit is the MC34063A IC (IC1), a versatile monolithic control circuit specifically designed to contain the primary building blocks needed for DC-to-DC converters, including an internal temperature-compensated reference, a comparator, a duty cycle controlled oscillator, and a high-current output switch. When power is applied via the input connector (CON1 or CON2), the internal oscillator within IC1 triggers the switching cycle, repeatedly storing and releasing energy through inductor L1. As the internal switch cycles, the inductor generates high-voltage flyback pulses, which are then rectified and smoothed by a network of diodes and capacitors. Specifically, 1N5819 Schottky diodes (D1, D4) are utilized for their fast switching speeds and low forward voltage drop to efficiently route the high-frequency pulses, while 1N4007 diodes (D2, D3) and capacitors like C3 help stabilize the intermediate rails and final outputs at CON3 and CON4. The circuit also incorporates 5mm LEDs (LED1, LED2) to visually indicate power status and active output rails. By managing the switching duty cycle, the MC34063A continuously monitors and maintains the desired stepped-up voltage levels across varying load conditions, providing a steady power source from a fading battery.